Esthetic dentistry/ dental implant courses by Indian dental academy

ESTHETIC DENTISTRY CONTENTS  INTRODUCTION  PRINCIPLES AND FUNDAMENTALS OF ESTHETICS  FACTORS OF ESTEHTIC DENTOFACIAL COMPOSITION AND THEIR CLINICAL SIGNIFICANCE  ESTHETIC DIAGNOSIS AND TREATMENT PLANNING  ESTHETIC TREATMENT MODALITIES o ESTHETICS WITH BLEACHING o ESTHETICS WITH COMPOSITE o ESTHETICS WITH CERAMIC o ESTHETICS WITH PERIODONTICS o ESTHETICS WITH ORTHODONTICS o ESTHETICS WITH IMPLANT  CONCLUSION  BIBLIORAPHY

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INTRODUCTION ‘Beauty is in the eye of beholder’ Beauty in itself is a combination of reality and personal perception.

Beauty can be interpreted differently by different people. For many centuries poetry and literature, both alike, have sung the praise of beauty.

Through the ages different cultures and races have had their own concept of beauty, smile played a major role in it. For e.g. Japanese custom of decorative tooth staining called ‘Ohaguro’ is a 4000 year old custom that is described as a purely cosmetic treatment, the procedure had its own set of implements, kept as a cosmetic kit.

Although times have changed, human nature has not. Just as our predecessors sought solution to their esthetic problems so do we.

Mouth is the one of the focal points of the face, so smile plays a major role in how we perceive ourselves, as well as the impression we make on people around us. “Smile” is the most beautiful of all the expressions. Pleasing appearances often means the difference between success and failure in both our personal and professional life.

Dr. Charles Pincus developed the concept of dental esthetic, in 1930s while creating a perfect smile for Hollywood film actors.

Some decades ago, esthetics was considered at best, a fortuitous by product of dental procedure. In the years that have ensued, esthetics have taken its rightful place along with functionality as a bonafide objective of dental treatment. The revolution that has transpired, complementing theory with technology and advanced methodology.

Today’s era of cosmetic and esthetic dentistry has placed emphasis on a confident and captivating smile. A well designed smile is a product of

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consolidated efforts accomplished by accurate diagnosis methodical treatment planning, use of advanced materials. Modern dentistry not only provides us with better materials and technology, but also ensures that today’s procedures are performed with minimal discomfort and maximum safety.

Esthetic dentistry strives to merge function and beauty with the values and individual needs of every patient. Esthetic dentistry involves a certain attitude, as well as artistic ability and technical competence.

This library dissertation is an effort to provide a practical, simple approach towards diagnosis, treatment planning and execution of esthetic dentistry.

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FUNDAMENTALS AND PRINCIPLES OF ESTHETICS Esthetic Dentistry: Can be defined as the art and science of dentistry applied to create or enhance beauty of an individual within functional and physiological limits.

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PRINCIPLES OF COLOR

Color , as the eye interprets it , is either a result of absorption or reflection . In absorption a white light is passed through a filter . The colors that pass through the filter and reach the eye are perceived as the colour of the filter . In reflection , as with solid objects , the color that we see is the portion of the spectrum that is reflected back to the eye Light entering the eye stimulates the photoreceptors rods and cones in retina .

The energy is converted into nerve impulses and carried through the optic nerve into the occipital lobe of the cerebral cortex . The rod cell are responsible for interpreting brightness and value . The cone cells function in hue and chroma interpretation .

Dimensions of color a) Hue b) Chroma c) Value

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Hue The name of the colour is derived from hue. The visible spectrum, ranging from 380nm to 750nm, produces a stimulus that evokes a response known as hue. In Munsell , s words , “ It is that quality by which we distinguish one color family from another” .

Generally the rare six families ; violet ,blue,green,yellow,orange and red .

The color wheel Types of hue: 1) Primary hues The primary hues – RED, YELLOW AND BLUE –forms the basis of the dental color system.

2) Secondary hues The mixture of any two primary hues forms a secondary hue . When red an blue are mixed they create violet , blue and yellow create green , and yellow and red create orange . Altering the chroma of the primary hues in a mixture

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changes the hue of the seconday hue produced . Primary and secondary hues can be organized on the color wheel with secondary hues positioned between primary hues ..

3) Complementary hues Color directly opposite to each other on the color wheel are termed complementary hues . A peculiarity of this system is that a primary hue is always opposite a secondary hue and vice versa . When a primary hue is mixed with a complementary secondary hue , the effect is to “cancel” out both colors and produce gray . This is the most important relationship in dental color manipulation Complementary hues also exhibit the useful phenomenon of intensification . when complementary hues are placed next to one another , they intensify one other and appear to have higher chroma .

Chorma Chorama is the saturation or intensity of the hue ; therefore it can only be present with hue

. In Muncell s word “It is that quality by which we

distinguish a strong color from a weak one” .For eg to increase the chroma of the porcelain restoration more of that hue is added . Chroma is the quality of hue that is most amenable to decrease by bleaching . In general , the chroma of teeth increases with age .

Value Value is the relative lightness or darkness of a color . A light tooth has a high value ;a dark tooth has a low value .It is not the quantity of the color rather than quality of brightness . Value is the only dimension of color that can exit by itself .

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Properties of color 1) Opacity 2) Translucency 1) Opacity When light strikes a surface , it is either totally reflected ,totally absorbed, or combination of both . Opaque objects reflects all or most of the light that is incident on them.

An opaque material does not permit any light to pass through . It reflects all the light that is shined on it , For eg ; In porcelain –fused to metal restoration must have a opaque porcelain applied to the metal substructure to prevent the color of metal from appearing through the translucent body and incisal porcelains.

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2) Translucency When part of the light incident on an object is transmitted , while the rest is scattered , the property of the object is known as translucency. Translucent materials allow some light to pass through them . Only some of the light is absorbed . Translucency , in effect is the three dimensional spatial relationship or representation of value . There might be inter-tooth as wellas intra – tooth differences in the translucency . Translucency provides realism to an artificial restoration.

Metamerism It is a phenomenon that can cause two color sample to appear as the same hue under one light source , but as un matched hues under a different light source .

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For eg : A shade guide tooth matches the natural tooth under incandescent light but not under fluorescent light . this can be attributed to the difference in radiant energy of two different wavelengths of light .

The stimulus varies according to the difference in the radiant energy leading to a perception of a different color . The standardization of lighting condition during shade matching diminishes the effect of metamerism .

Fluorescence The emission of light by an object at a different wavelength from that of incident light is called fluorescence . The emission stops immediately on removal of incident light. Teeth fluorescence with a stimulus in the range of 340nm to 410 nm .This spectrum is in blue range . thus , according to the principles additive color , the emitted blue light acts with yellowness of tooth to produce a whiter tooth . Fluorescin pigments incorporated in the ceramic restoration by the ceramist and in composite restoration by the manufacture may thus be advantageously used in altering the perception of the final result Gloss Gloss is an optical property associated with a smooth surface that produces lustrous surface appearance and thus reduces the effect of color difference It also lightens the color appearance and is associated with a smooth surface which can be created on a restoration by finishing and polishing procedures that increases the brilliance of the final result COLOR CHARACTERISTICS OF TEETH • In a newly erupted tooth , the superficial layers of enamel are most opaque . They appear as though they have white frost .This superficial frosted enamel may have a higher organic component is less mineralized and as more empty space between the enamel crystals all of which causes increased opacity

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• Due to high opacity, the superficial enamel of young tooth is very reflective .the croma of a tooth, which primarily comes from dentin will be lower due to the masking effect of the young enamel. As the enamel gets thinner the dentin becomes more obvious. The nature thickness of enamel is greatest at the incisal and least at the cervical. Croma is greateast a the cervical and decreases toward the incisal.

• Young enamel is more permeable. Young teeth dehydrate quickly and older teeth with enamel worn thin will not dehydrate much.

• With age, only the deeper more translucent enamel remains.

• When light enters a tooth, it may reflect off many surfaces within the tooth before it exits substantially changing the character. The more scattering that takes place in the enamel, the higher the value.

• Enamel rods and the surrounding interprismatic substances are positioned perpendicularly to the thin dentin layer. This crystalline structure permits light to pass through, which then reflects the underlying color of the dentin. The prism structure of enamel influences light transmission resulting in anisotrophy, directionally dependant light propagation. We sometimes can see a highly pigmented are from one angle but not another angle. The translucency of enamel varies with the angle of incidence, wavelength and dehydration.

• In the spectrum of rainbow, the shades(hues) of natural teeth tend to be in the yellow range. If we were to place the rainbow on line, then the A shade is more towards the red end of the yellow spectrum and B shades is more to the green end of the yellow spectrum. Most teeth are closer to A on the vita shades guide but there is a much wider spectrum of natural hues than most shades guides provide.

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• The thickness of dentin, the size of the pulp chamber, and the vitality of the pulp tissue are different stages of tooth development. Teenagers generally have a larger pulp chamber that add red. With secondary dentin formation, the pulp chamber decreases in size and the teeth becomes less red with age.

• Older dentin or sclerotic dentin is darker (higher chroma, lower value) and it has more green and blue. Young dentin is more red-yellow. (CIE Lab color spaces a* and b* go negative with age). There is a positive linear correlation between age and chroma of the roots. Through the dentin undergoes a color shift from red yellow towards yellow, the overall color of older teeth is redder than in youth because there is less bright enamel covering the red dentin due to wear.

• Different teeth in the arch can belong to different hue families. a * (red to green gradient) is highest (most red) in canines, then centrals, then laterals. b* (yellow to blue gradient) is highest (most yellow) in canines, then laterals. then centrals.

• Value is mainly determined by qualities of the enamel layer in the form of reflectivity and opacity. As the superficial layers of the enamel surface are worn, the translucency goes up and the dentin becomes more visible and dentinal chroma begins to influence value more.

• To raise the value in a restoration that needs to be highly translucent( translucency normally drops value), the brightness needs to be built into the dentin instead of the enamel.

• Value is typically lowest at the cervical, then at the incisal, and highest in the middle third of the tooth 39. Value increases going medially from maxillary canines to centrals

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• The mammelons and interproximal contact areas usually show the most translucence.

• The cervical hue is always redder than the middle or incisal.

• Translucency is greatest in laterals therefore; opalescence (primarily in translucent enamel) is most evident in the laterals.

• Cuspids show very little translucency.

• Remember that the upper cuspids are often one to two full shades darker in chroma than the maxillary incisors and will sometimes give a better clue to the average hue family.

• The hue and chroma of natural teeth are not constant. If a laboratory uses the same porcelain for all the teeth in an arch, it will make the mouth look flat. A natural 3-dimensionality can be developed with chroma gradients getting darker from the centrals on back.

SHADE SELECTION Shade selection is a complex procedure due to the variations and differences in the optical properties of the new generation of cosmetic restorative materials. It can be well accomplished by understanding the fundamentals of color and adopting a proper methodology of matching shades. The effective communication with the laboratory and precise fabrication and meticulous finishing of the restoration will affect the color of the final restoration.

Shade guides One can avail of subjective or objective method of shade selection.

1) Conventional shade tabs (Subjective) 2) Advanced computer imaging analysis (Objective).

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Conventional shade guide system: This subjective method towards obtaining an optimum results is most widely accepted and used. The shade tabs utilized are visual guides and not definitive answers. The most popular and commonly used shade guides are Vitapan Classical, Ivoclar Chromascope and Vitapan 3D Shademaster. The Vitapan Classical categorizes hue as A, B, C, D with reddish-brown, reddish-yellow, grayish and reddish-grey shade respectively, while the Chromascope system uses numbers viz. 100, 200, 300, 400 and 500 for white, yellow, orange, grey and brown respectively. The Vitapan 3D Shademaster, based on the work of Miller and developed by McLaren, has indications left (L) and right (R). “L” indicates a tendency towards yellow and “R”, towards red.

The chroma is communicated by increasing numbers in all the three systems.

3D Shademaster is the only one that addresses value first viz., on a scale of 1 to 5, 1 is the brightest white4 is the darkest.

A value based shade guide is more accurate since our eyes are more sensitive to changes in brightness / darkness and chroma than to the subtle changes in hue.

Advanced computer imaging analysis: In the conventional shade guide system, selection of color is dependent on the subjective knowledge and skill of dentist leading to inconsistencies of shade matching. This is further compounded by variables like lighting, metamerism,

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illusions and aging leading to great variability in shade selection. Hence, a need for objective standards became evident.

Digital shade analysis eliminates the subjectivity of color analysis and provides exact information for laboratory fabrication of the prosthesis. The influence is more objective can be repeatedly verified, is not influenced by external factors like surrounding environment and involves less chair-side time. The reading can be translated to materials that can reproduce those characteristics in the fabricated restorations The other features that complicate color matching like translucency, surface gloss, fluorescence, inhomogeneous tooth structure are also incorporated in the readings. A few models are available in the market, but are very expensive.

Shofu shademaster –ex chromameter is a spectrophotometry based shade determination device that employs point source references of information. The drawaback is that the information remains subjective in nature.

Another system, Cortex machine-shade scan system, analyses tooth images and objectively relates their characteristics based on color and translucency. Cross checking with a database of known shade guides as well as additional scanning of new shade guides is also possible. But this system does not provide an exact method for laboratory fabrication.

Thus, in spite of certain drawbacks, technology based shade guide systems hold a promising future in helping to mimic nature to the fullest.

The greatest art is ……. To Disguise the Art Guidelines for Shade Taking:  Make the shade selection at the beginning of the procedure as well as over different appointments (diagnosis, prophylaxis etc) and cross check these observations.

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 View the patients at eye-level. The operator should stand between the light source and the patient.  In a contrasting environment, colors look more intense and brighter.

Hence it is wise to ask the patients to remove artificial lip color. The patient’s drape and assistants clothing may also influence color matching.  Place the tabs as close as possible to the area that is being checked.  Moisten the tab and eliminate the worst match.  Evaluate the value (upper to lower). Value is the most important factor in shade matching. If the value blends, small variation in hue and chroma will not be noticeable. The value is to be matched with eyes half-closed.  After value, mark the translucency.  Match the chroma (more or less saturated) and finally, hue is that order.  To avoid hue sensitivity, rapid observation is made for 5 seconds (not more than 20 seconds). Look away, ideally stare at a blue surface, which will readapt the vision to the orange-yellow portion of the spectrum.

Staring at a tooth for 5 seconds causes yellow adaptation and blue sensitivity. Stare at a blue card to become blue adaptive and yellow sensitive.  Match prior to tooth preparation, since preparation dehydrates and changes color due to the debris of preparation. Ensure that the teeth are cleaned and unstained by rubber cup prophylaxis.  Never select shades after prolonged and fatiguing operative surgery. The best time for shade selection is when the dentist is fresh.

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 When in doubt about two tabs, hold them side by side on the tooth to be matched and compare to get the finest match.  Match the tab with the opposing tooth also.  Metamerism complicates color matching, as the tabs look different under different light sources. The best approach is to use three light sources: cool white fluorescent light, incandescent operatory lamp and day light if possible.  When in doubt, always select higher value and lower chroma, since it is easy to lower value and increase chroma.  Shade tabs of different batches don’t always match, hence it is wise to send the actual selected shade tab to the technician.  Make a decision regarding relative translucency, area of hypocalcification, increased saturation, crack lines surface texture and other characterization. Make a drawing of the facial surface and record all patient information graphically.  If possible, take photographs with shade tabs in place.

THE PRINCIPLES OF FORM Perception: As we look at a tooth in an environment of other teeth we perceive unconsciously many qualities of that tooth. Perceptions about color, size, shape, age, and gender are based on certain natural biases indigenous to an individual’s cultural background. Perceptual biasis can be divided into two types: cultural and artistic.

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Cultural biases Cultural biases are naturally occurring environmental observations about the world around. We perceive that darker, heavily worn, highly stained, longer teeth belong to an older person because we know that teeth naturally darken, wear, and stain in grooves and along the cervical area with age, and that they lengthen because of gingival recession. We perceive rounded, smooth-flowing forms are feminine, whereas harsher, more angular forms are masculine.

Masculine and Feminine: Culturally defined masculine qualities may enhance the appearance of a women. However, usually these masculine nuances look best on a woman with stereotypically feminine features. Square, angular anterior teeth, therefore, may be desirable for a more “feminine” woman, but on other women this tooth shape may not be as flattering. In Western culture, contrast evokes a certain allure. With no contrast, the allure is gone.

The golden proportion:  Has been recognized in the beginning of the history.  It was given by Pacioli.  The proportion is 1.0 to 1.618.  The relationship links geometry to mathematics, hence it is called as “Sacred geometry”, “magic numbers”, “Golden cut”.  The golden preparation is not only symlolizes beauty and comfort at a perimeter level but it is also the key to much of normal morphology.

In case of the teeth, the lower central incisor may be used as a starting reference. Interestingly the upper central incisor has a golden, phior 1.618 proportion to the lower incisor, and total width of both lower centrals are golden to that of the upper incisors. As a underlying concept, these values so 17

often expressed in nature – seen to display a basic phenomena of perfection.

The phenomenon is often referred to as a part of “Sacred geometry�.

Artistic Biases Artistic biases are inherent in our perception of form.

1) The most important of these is the perception that light approaches and dark recedes; this is the principle of illumination.

2) The second artistic bias of great importance in dentistry is the use of horizontal and vertical lines, this is called of principle of line.

1) Principle of illumination The law of the face The law of the face is the most important single concept in shaping dental restorations. Understanding this concept and its interplay with the concept of light and dark enables the esthetic dentist to shape all esthetic restorations correctly.

The face of a tooth is area on the facial surface of anterior and posterior teeth that is bounded by the transitional line angles as viewed from the facial (buccal) aspect. The transitional line angles mark the transition from the facial surface to the mesial, cervical, distal, and incisal surfaces. The tooth surface slopes lingually toward the mesial and distal approximating surfaces and

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toward the cervical root surface from these line angles. Often no transitional line angle appears on the incisal portion of the facial surface; in this case the face is bounded by the incisal edge or the occlusal trip. Shadows created as light strikes the labial surface of the tooth begin at the transitional line angles.

These shadows delineate the boundaries of the face.

The apparent face of a tooth is the portion that is visible to the viewer from any single view. The perimeter of the apparent face is dictated by the position of the viewer relative to the tooth. For example, from the front view the entire incisor faces are visible, but usually only the mesial half of the faces of the maxillary canines are visible from this angle.

The law of the face states that in order to make dissimilar teeth appear similar, the one should make the apparent faces equal. Creating equal apparent faces in two dissimilar adjacent teeth produces dissimilar areas outside the transitional line angles (i.e., outside the faces). These dissimilarities are esthetically acceptable because they are essentially invisible; the similar faces of the teeth catch the light and appear to protrude, whereas the dissimilar areas are in shadow and appear to recede.

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When the transitional line angle cannot be repositioned on a ceramic restoration, the artistic principle of illumination can be employed. A portion of the tooth can be stained darker to create the illusion that the transitional line angle has been moved and that the portion of the tooth is receding. In reality the tooth contour remains unchanged. Only the “apparent face� should be manipulated, not the actual face. The becomes particularly significant in posterior regions where the apparent face significantly differs from the actual face.

Canines and the law of the face The concept of the apparent face becomes more important when dealing with teeth posterior to the incisor teeth. From a frontal view only a portion of the canine and posterior teeth are visible. In the frontal view the canine face is bounded by the mesial transitional line angle, the cervical transitional line angle, and the midlabial ridge. Usually the distal half of the tooth is not visible from a frontal view. The left and right side views cannot be seen simultaneously and are of secondary importance. Four steps are required to blend a poorly shaped canine into a smile.

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Principle of line: Horizontal lines – in the form of cervical staining, texturing, white hypoplastic lines, or long, straight incisal edges – create the illusion of width. Widening the face also produces an illusion of width.

Vertical lines in the form of accentuated developmental grooves, hypoplastic lines, and vertical texturing accentuate height. Incisal edges of anterior teeth carved to slope cervically toward the distal area with larger incisal embrasures and narrower (mesiodistally) incisal edges create an illusion of increased height. Narrowing the face also creates this illusion. These same concepts apply for clothing and makeup. Individuals wearing clothing with vertical lines appear thinner. Conversely, horizontal stripes accentuate width. To “lengthen” and “slim” the nose with cosmetics, a light highlighter is applied in a vertical line down the center bridge of the nose. Then a darker contour shade of makeup is applied on each side of the nose to make that area recede.

Age: Older teeth: 1. They are smoother.

2. They are darker 3. They have a higher saturation 4. They are shorter incisally 21

5. They are longer gingivally 6. They exhibit more wear, even on incisal edges with small incisal embrasures.

7. They have wider, more open gingival embrasures.

8. They are more characterized.

The lower incisors exhibit flat broad incisal edges, which shows a dentin core.

Younger teeth: 1. They are more textured.

2. They are lighter 3. They have a lower saturation 4. They have a gingival margin at approximately the cementoenamel junction.

5. They have incisal edges that make the laterals appear shorter than the incisors or canines.

6. They have significant incisal embrasures.

7. They have small gingival embrasures.

8. They have light characterization, often with white hypoplastic lines or spots.

Clinically, the ultimate esthetic goal is to make artificial prostheses appear natural. Beautiful natural teeth or artificial substitutes should be harmonious with the patient’s personality, age, and gender.

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Gender: Lombardi described a theory of anterior esthetics in which he proposed that the age, gender, and personality of a person was reflected in the shape and form of the teeth. Factually, the concept of sexual dimorphism is difficult to prove or disprove. This concept should be considered in the light of cultural bias.

Feminine: Feminine teeth are more rounded, both on the incisal edges and at the transitional line angles. The incisal embrasures therefore are more pronounced. The incisal edges are more translucent and white hypoplastic striations may be used to give the illusion of delicacy. The translucency on the incisal edges appears as a gray line in the incisal one-eighth of the facial surface paralleling the incisal edge with a white hypoplastic rim on the edge.

Masculine: Masculine teeth are more angular and rugged. In older men chroma is greater and body color often extends to the incisal edges. The incisal embrasures are more squared and not a pronounced. Characterization is often stronger, incorporating darker craze lines.

Cultural and artistic biases are central to understanding dental esthetics. They must be thoroughly understood so that the dentist can use these biases artistically to create illusions to satisfy the esthetic demands of the patient.

Only then can the technically proficient dentist rise to the level of an artist, providing a higher level of care.

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FACTORS OF ESTHETIC DENTO-FACIAL COMPOSITION AND THEIR CLINICAL SIGNIFICANCE The esthetic orientation of the dental composition with the entire facial composition can be achieved by taking in to the consideration.

1. The references 2. Smile elements.

3. Proportions.

4. Symmetry.

The references: The dento facial frame constitutes the teeth and gingiva related to the lips and then to the entire face. The oral frame is determined by the anatomy and mobility of the tissues when in function surrounding the teeth and gingiva.

The exposed portion of the oral elements i.e. teeth and gums within the oral frame during a smile is called the smile window.

The anatomical elements of the face and the biological elements that include the functional and phonetic elements, provide the reference frames, guidelines and points. These elements help in achieving a general sense of orientation and diagnosis.

References can be classified into: a) Horizontal reference. b) Vertical reference. c) Sagittal reference. d) Phonetic reference.

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a) Horizontal reference: The horizontal perspective of the face is provided by the interpupillary line, the ophriac and the commissural line.

The inter-pupillary line helps to evaluate the orientation of the incisal plane, the gingival margins and the maxilla. An imaginary horizontal line through the incisal plane and the gingival margins should be visibly parallel to the inter-pupillary line. This helps to diagnose any asymmetry in the tooth position or gingival location. When an imaginary line is drawn across the gingival margins, it may not be parallel to the inter-pupillary line indicating a certain degree of canting of the maxilla. Certain amount of canting of maxilla is considered but severe canting may require an inter-disciplinary approach involving surgical repositioning of the maxilla. b) Vertical references: The facial midline serves to evaluate the location and axis of the dental midline and the medio-lateral discrepancies in tooth position.

The inter-pupillary line and the facial midline emphasize the ‘T’ effect in a pleasing face. The dental midline, if perpendicular to the inter-pupillary line and coinciding with the bridge of the nose and the philtrum, produces an attractive orientation of the smile. Ideally the dental midline should coincide with the facial midline. The dental midline of the upper arch and the lower arch may not coincide. Sometimes a perfectly centred midline creates an artificial appearance while a slightly oblique dental midline appears natural.

Axial inclination: Is the direction of the anterior teeth in relation to the central midline and becomes progressively more pronounced from the central incisor to the canine. There is a definite mesial inclination to all the anterior teeth related

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to the midline. The axes of the premolars and the first molar on either side also show mesial inclination in relation to the midline.

The perception of tooth inclination can be viewed from the frontal aspect around the central vertical midline, which acts like a fulcrum around which axial inclination of teeth on either side exhibit a phenomenon of balance of lines. Natural smiles show a deviation from these standard axial inclinations. Deviations in axial inclination cause a visual tension when beyond the point of equilibrium. c) Sagittal reference: Soft tissue analysis at a standardized position helps in studying the profile of an individual. The contours of the upper and lower lips and the lip supports is determined by the position of the anterior teeth and can be used as a guide for the placement of teeth when planning restorations. The lip protrusion, the amount of prominence of chin, recession or prominence of the nose and its degree, all help in profile analysis for diagnosis and treatment planning.

The E-line or esthetic line is an imaginary line connecting the tip of the nose to the most prominent portion of the chin on the profile. Ideally the upper lip is 1-2mm behind and the lower lip 2-3mm behind the E-line. Any change in the position of the E-line indicates the abnormality in the upper or lower lip position.

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The main support of the upper lip is contributed by the gingival two thirds of the maxillary central incisors rather than the incisal one third.

The relationship of the maxillary incisal edges to the lower lip is a guide for the placement of the incial edge position and length. The pronunciation of the ‘F’ and ‘V’ consonants helps determine the position of the incisal edges.

On pronouncing ‘F’ and ‘V’ the incisal edges should make a definite contact at the inner vermillion border of the lower lip. Thus the position of the incisal third of the maxillary central incisor can be determined. The failure to contour the incisal third is a common mistake seen in anterior restorations. d) Phonetic references: Certain sounds are made by touching the lips or the tongue against maxillary teeth. Phonetics play a part in determining maxillary central incisor design and position.

‘F’ and ‘V’ sounds are used to determine the tilt of the incisal third of the maxillary central incisors and their length. The ‘M’ sound is used to achieve a relaxed rest position and if repeated at slow intervals can help evaluate the incisal display at rest position. ‘S’ or ‘Z’ sound determine the vertical dimension of speech. Its pronunciation makes the maxillary and the mandibular anterior teeth come in near contact and determine the anterior speaking space. The amount of posterior speaking space varies with the

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amount of mandibular protrusion necessary to bring the anterior teeth in near contact for the ‘S’ sound.

In patients with Angle’s Class I or Angle’s Class II occlusal relationships, the posterior speaking space is more than the anterior speaking space. These patients can accept slight changes of vertical dimension of occlusion as long as it remains within the limits of the vertical dimension of speech. In Angle’s Class III occlusal relationships the anterior and posterior speaking space is approximately the same, therefore such patients may not tolerate variations of the vertical dimension of occlusion as it would interference with the speaking space.

Smile elements: As said by Darwin, it appears that we all smile the same language.

Classification of smile: 1. The commissure smile.

2. The cuspid smile.

3. The complex smile.

1. The commissure smile is the most common pattern, seen in approximately 67% of the population. In this smile, typically thought of as a Cuspid’s bow, the corners of the mouth are first pulled up and outward, followed by the levators of the upper pattern, the lowest incisal edge of the maxillary teeth are the central incisors. From this point, the convexity continues superiorly with the maxillary first molar being 1 to 3mm higher than the incisal edge of the centrals. A spontaneous smile results in a maximum movement of the commissure from 7 to 22mm. likewise, the average direction of movement of the 28

commissure is 40 degrees from the horizontal (range 24 to 38 degrees).

The direction of movement of most smiles is to the helix-scalp) junction.

When comparing the left to the right side, a large difference may exist in the extent of movement, but there is only a relatively slight discrepancy in the actual direction of movement when comparing left to right.

Personalities with recognizable commissure smiles include Jerry Seinfeld, Dennis Quaid, Jennifer Aniston, Frank Sinatra, Jamie Lee Curtis and Audrey Hepburn.

2. The cuspid smile is found in 31% of the population. The shape of the lips are commonly visualized as a diamond. This smile pattern is identified by the dominance of the levator labii superioris. They contract first, exposing the cuspid teeth, then the corners of the mouth contract to pull the lips upward and outward. However, the corners of the mouth are often inferior to the height of the lip above the maxillary cuspids. Often there is a similar inferior turn of the maxillary premolars as opposed to the continuous convexity of a commissure smile.

This “gull wing� effect is silhouetted by the gingival tissues, which correspondingly mimic the shape of the upper lip. In this smile pattern, the maxillary molars are often at or below the incisal edge of the central incisors. Eminent personalities with cuspid smiles include Elvis, Tom Cruise, Drew Barrymore, Sharon Stone, Linda Evangelista and Tiger woods.

3. The Complex smile characterizes 2% of the population. The shape of the lips are typically illustrated as two parallel chevrons. The levators of the upper lip, the levators of the corners of the mouth, and the depressors of the lower lip contract simultaneously, showing all the upper 29

and lower teeth concurrently. The key characteristic of this smile is the strong muscular pull and retraction of the lower lip downward and back.

In this smile pattern both maxillary and mandibular incisal planes are generally flat and parallel. Some celebrated personalities with complex smiles include Julia Roberts, Marilyn Monroe, Will Smith and Oprah Winfrey.

Stages of a Smile: There are four stages in a smile cycle: • Stage I lips closed.

• Stage II resting display.

• Stage III natural smile (three-quarters).

• Stage IV expanded smile (full).

Types of Smiles: There are five variations in which dental and / or periodontal tissues are displayed in the smile zones: • Type 1 maxillary only.

• Type 2 maxillary and over 3 mm gingiva.

• Type 3 mandibular only.

• Type 4 maxillary and mandibular.

• Type 5 neither maxillary nor mandibular.

In the vast majority of cases, people will be categorized under a single type, although it is possible to combine types, if necessary. For instance, a patient may have a complex smile prominently showing maxillary and mandibular teeth and have a maxillary ‘gummy’ smile displaying more than 3 mm of gingiva. This odd smile pattern would be a type 2, 4.

The characteristics which can be used as a guidline for creating a pleasant smile are:

30

• The maxillary central incisors exhibit a strong presence by their size and form reflecting the personality of the individual.  Dominance of a central element is the prime requisite of an esthetic dentofacial composition.

• The maxillary lateral incisors and the canines complement the central incisor in terms of proper shape and form.  The exhibit dominance of central incisors the subsequent

elements

should

be

strong

and

complementary.

• Although numerically all proportions of the anterior teeth do not follow the rule of golden proportion, the teeth are so placed that they appear in suitable proportions with each other.  To give a definite character to the smile, relative proportion between all anterior teeth should be pleasing.

• Similar recurring ratios are observed in the teeth from the central incisor to the premolar.  The importance of order in the composition is crucial for visual equilibrium.

• Well coordinated movements of the lips with the other peri-oral musculature and corresponding harmonious facial expressions, contribute to the pleasant face during smile.  Smile is dynamic and centralized, exhibiting a strong contrast related to the neighboring areas, imparing dominating influence on the face.

31

• The complexion and texture on the face contrast with the lip color, gingiva nd the teeth leading to a distinct demarcation between the oral and the facial frame. ďƒ˜ A strong centralized element creates unity and results in an immediate, harmonious composition.

Lip and Lip Lines: The length, the curvature and the shape of the lips significantly influence the amount of tooth exposure during rest and in function. While smiling, the upper lip curvature is generally expected to run upward from a center portion to the corner of the mouth during normal muscle function.

Any muscular atrophy, degeneration, hypertrophy or neuromuscular disorders can lead to asymmetrical and strained movements. The ideal location of the upper lip height relative to the central incisor is at its gingival margin or 1mm above it displaying the inter-dental papilla between the two central incisors during moderate smile.

The average maxillary incisor display with the lips at rest is 1.91mm in men and 3.40mm in women.

Upper lip line helps to evaluate the length of the maxillary incisor exposed at rest and during smile and the vertical position of the gingival margins during smile.

The upper lip line can be classified as low, medium or high depending upon the amount of tooth or gingival display that is available at rest or during a moderate smile. The gingival margins may be displayed in high lip line cases. The most apical position of the gingiva over the facial aspect of the maxillary central incisor and canine is slightly distal to the long axis of the tooth while in the maxillary lateral incisor it is at the long axis of the tooth. This is called the gingival zenith.

32

A smile can be termed “toothy” if more than 6mm of incisal display is seen at rest position or ‘gummy’ if more than 3mm of gingival tissues are displayed in moderate smile.

Lower lip line helps to evaluate the buccolingual position of the incisal edge of the maxillary incisors and the curvature of the incisal plane.

Smile line: It is an imaginary line passing through the incisal edges of the upper anterior teeth. The smile line usually coincides or runs parallel to the inner vermillion border of the lower lip. In a youthful smile the incisal edges of the central incisors and canines are aligned on a convexity and are longer than the lateral incisors, incisal embrasures gradually deepen from central incisor to the canine, giving the appearance of the wings of a gull. Thus the incisal plane is said to have a gull-wing appearance. When the incisal edges of the central incisors and canines are aligned on a convexity the incisal plane is convex.

Reduced incisal embrasures and leveling of the gull-wing effect as in a straight smile line is associated with aging.

Negative space: Negative space is a dark space appearing between the jaws and the mouth opening either at the corner of the mouth or around the buccal aspect of the posterior teeth during active smile and laugh.

It is an important factor which brings about a harmonious cohesion between the various elements of the smile. The lateral negative space exists between the labial surface of maxillary teeth and the corner of the mouth while the buccal

33

negative spaces appear in the buccal vestibule on either side of the buccal aspect of posterior teeth. Obliteration of these essential spaces by dental elements like bulky canines, wide arches or over-contoured restorations can lead to an unattractive smile. Excessive negative spaces seen in cases of missing premolars or palatally placed posterior and a constricted arch also appear unesthetic.

PROPORTION: The position of the tooth in the arch, the relationship between the width, the length and the face of the tooth can also be numerically established in relation with certain anatomic landmarks.

The central incisors are predominant as they reflect the patient’s personality, lateral incisors provide the charm and canines the strength. The shape of the central incisor, whether square, ovoid or triangular, is often related to that of the face seen upside down. The measurements will be in accordance with the width of the face, width of the dental arch, inter-pupillary distance and volume of the lips.

A central incisor is considered perfectly proportionate when the maximum width is approximately 75% of the maximum length (of the clinical crown).

This is the ideal width to length ratio). ‘Golden Proportion’ is expressed in numerical form and applied by classical mathematicians such as Euclid and Pythagoras in pursuit of universal divine harmony and balance. It has been applied to a lot of ancient Greek and Egyptian architecture and may be expressed as the ratio 1.618:1.

34

If this ratio is applied to the smile made up of the central, lateral incisor and the mesial half of the canine, it shows that the central incisor is 62% wider than the lateral incisor which in turn is 62% wider than the visible portion of the canine which is the mesial half, when viewed from the front.

SYMMETRY: The composition has symmetry when identical recurring ratios with reference to size, shape and position exist on either side of a dividing line or around a center. Dental symmetry relates to right and left sides of the midline.

For harmony, certain symmetries are essential while certain asymmetries are acceptable. Harmonious facial features should be more symmetrical close to the facial midline and can be more asymmetrical away from the facial midline.

The goal is to strike a pleasing balance between idealism and deviation because naturally esthetic dentitions do have subtle asymmetries. Maxillary central incisors must be kept within reasonable symmetrical limits; the deviation of the dental reconstruction should be accommodated by the asymmetry of the lateral incisors.

35

Acceptable range of anterior teeth relationships: Features Dental midline related to

Ideal Situation Straight

Acceptable deviation Slightly oblique

facial midline Teeth inclination in relation

Straight or slightly

Mesial inclinations

to midline

mesial

acceptable, avoid distal

Alignment of teeth in all

Aligned in all three

inclinations Aligned in at least two

three planes i.e. labio-

planes

planes.

Symmetrical

Incisal edges of central

lingual, mesio-distal and rotation along the axis of the tooth.

Position of gingival margins, incisal edges and

incisors may be misaligned

distal incisal angle in case

if gingival margins are

of central incisors.

slightly asymmetrical. The distal incisal angle could be

Incisal plane

Either convex or

asymmetrical.

May be slightly less convex

Incisal embrasure

sinuous Should gradually

but not straight Incisal embrasure may be

deepen from central

less deep but not absent

incisor to canine Should be bilaterally

Could be slightly

symmetrical

asymmetrical in shape,

Lateral incisors

gingival margins and Canines

Labiolingual

rotations.

Labio-lingual inclination

inclinations should be could be slightly symmetrical

asymmetrical

ESTHETIC DIAGNOSIS AND TREATMENT PLANNING A meticulous esthetic diagnosis followed by a well-defined treatment plan is the foundation of successful esthetic dental treatment. The definitive treatment 36

plan should address the treatment periods, expenses, treatment sequencing and all aspects related to the function and maintenance of the anticipated result.

Most esthetically motivated patients are eager to begin corrective treatment.

Nevertheless, their enthusiasm and, at times, self-diagnosis should not influence the dentist's esthetic diagnosis. It is essential that the patient make an informed decision, after receiving a thorough explanation of his/her condition and the ramifications of treatment, including the advantages and disadvantages of each treatment alternative.

1. PATIENT HISTORY Information should cover aspects of: •

Medical history: allergies, systemic disorders, previous surgeries etc.

•

Dental history: past dental experiences, apprehensions, expectations etc.

•

Personal and Social history

2. CLINICAL EXAMINATION A clinical examination involves a thorough evaluation of facial and temporomandibular components and assessment of occlusal relationship, periodontal attachment, teeth and intra-oral soft tissues.

•

Facial components

Face form, symmetry along the midline,

relationships of various parts of the face, position of lips and chin from frontal as well as lateral aspect, relationship of horizontal and vertical references of face with respect to teeth and gums.

•

TMJ: Palpated and auscultated for clicking, crepitus, hypermobility and deviation.

37

•

Occlusal relationships' Occlusal pattern, type, contacts and path during mandibular movements

•

Periodontal attachments: Plaque, calculus, gingival inflammation, amount of attached gingiva, recessions, hyperplasia etc.

• Teeth: Caries, existing restorations, discolourations, wear facets, erosions etc.

3. ESTHETIC EVALUATION The following analysis chart covers the facial, dentofacial, dental and functional analysis. In case any abnormalities found in the soft tissues, hard tissues, TMJ and occlusal pattern, a thorough evaluation is recommended before esthetic treatment planning.

Visual Analysis Chart Facial Face forms

Square, round, oval, pear, tapered

Frontal perspective

Nasio-Iabial groove

Exaggerated

Mento-labial groove

Normal Adequate

Vertical height

More Less Competent

Lips

Incompetent Full

38

Dento-facial Inter-pupillary line

Upper lip line

Incisal plane

Parallel/not parallel

Gingival margins

Parallel/not parallel

Maxilla

Canting / not canting

Length of maxillary incisors visible at rest

<1mm 1 - 4mm >4mm

Vertical position of Low gingival margins during Average smiling High Lower lip line

Bucco-lingual position Touching of maxillary incisors Not touching Slightly covered Curvature of incisal plane

Convex Straight Concave/reverse

Facial midline

Dental midline

Center Right of center Left of center

Axis of dental midline

Straight Oblique

Moderate smile

Gingival display

<3mm >3mm

Gingival patterns

Esthetic Unesthetic

Vestibular space

Less (expanded arch) More (contracted arch)

Horizontal tooth display

6/8/10/12 teeth

39

Dental Teeth

Decayed, deficient restorations Missing Malformed Malaligned (overlapped/flared) Violation of width to length ratio or golden proportion Fractured, chipped, attrition, abrasion Discoloured Diastema Pathological migration Supra-eruption

Gingiva

Inflammation Recession, black triangles Hyperplasia Altered gingival display Pigmentation Frenal attachment

40

Functional Temperomandibular

Joint

clicking,

crepitus,

hyper-mobility,

joint

dislocation

Mandibular

Deviation while opening and closing, jerky

movements

movements

Occlusion

Antero-posterior plane Molar relationships Canine relationships Incisal relationships Vertical plane

Open bite Deep bite Edge to edge

Transverse plane

Rotation Cross-bite

Phonetics 'S' sound

Anterior speaking space

Adequate / deficient

Posterior speaking space

Adequate / deficient

Incisal edge of maxillary Touches inner incisor vermilion border Touches outer border of lower lip

'F' or 'V' sound

Does not touch lower lip Incisal display â&#x20AC;&#x2DC;Mâ&#x20AC;&#x2122; sound

< 1mm 1-4mm >4mm

41

SPACE ANALYSIS Space analysis helps the dentist to gauge the amount of space available during the treatment planning stage. The concept is to measure the widths of all the teeth and compare it with the space present in the arch. The normal length to width ratios of teeth should be borne in mind and the law of golden proportions should be closely followed to prevent violation of natural proportions. Thus, space maintenance for restorations in terms of illusions, rotations, overlaps etc. can be carried out as planned.

PROFILE ANALYSIS Patients with impaired dentofacial esthetics resulting from underlying skeletal problems can be identified wit the use of profile analysis.

The patient’s profile can be: • Straiqht / Orthoqnathic • Convex / Retroqnathic : Due to: - prognathic maxilla - normal mandible - Normal maxilla - retrognathic mandible Prognathic maxilla - retrognathic mandible Features: - normal/increased / decreased lower facial height - Lower lip trap, depending on the position of lower anteriors Deep mentolabial groove • Concave / Prognathic: Due to : retrognathic maxilla - normal mandible - Normal maxilla - prognathic mandible Retrognathic maxilla - prognathic mandible

42

Features: increase / decrease in lower facial height -

Maybe associated with habitual or pseudo Angle's Class III occlusal relationship.

DIAGNOSTIC AIDS Study casts Accurate study casts help give necessary inputs regarding intra-arch relationships like arch-length versus tooth size discrepancies; alignments; angulations and inter-arch relationships like Angle's classification, overbite, overjet, plane of occlusion etc. They also reveal functional relationships involving centric and protrusive interferences, working sidebalancing side interferences, wear facets etc.

Radiographs IOPA and bitewing radiographs are used to detect interproximal caries, bone levels and quality, periapical pathologies etc. Panoramic radiographs help to analyze

pathologic

lesions,

impacted

teeth,

teeth

angulations

etc.

Radiovisualgraphy has become extremely popular as it cuts down radiation by 80-90% and multiple different angle views cali be taken.

Intraoral camera Is a powerful communication tool as it provides instant visualization of the patient's teeth. It has the ability to easily transilluminate and photographically record hidden microcracks that could alter the treatment plan.

Extraoral camera Can record the whole oral frame including the smile window along with the smile line, lip lines, negative spaces, midline shifts, gingival asymmetries etc. It plays an important role in records for diagnosis and treatment planning, selfanalysis,

laboratory

communication,

patient

management,

marketing,

medicolegal purposes and scientific documentation.

43

Magnification loupes Help in accurate, detailed observation of tooth characteristics. Magnifying lenses of 2.5 diopter or greater are extremely valuable diagnostic tools.

T-scan occlusal analysis Is a computerized system that uses sensor technology to identify the location, timing and relative force of occlusal contacts.

Periodontal charting No part of the esthetic examination is more important than ascertaining the condition of the patient's supporting bone structure. The periodontal ligament of each tooth is thoroughly probed in six locations and charted. This can be done with either a traditional periodontal probe or an electronic device where the data is recorded electronically using a voiceactivated system.

Computer imaging Offers an unparalled method of visualizing your intended esthetic correction and the effect it can have on the face. It helps patients to make suggestions and is a brilliant motivational tool.

INITIAL THERAPY Initial therapy is required before esthetic treatment planning to arrest active pathoses, bring adequate health to the dentition or give the patient relief from pain. ď&#x201A;§ Periodontal therapy:control of all periodontal inflammation through scaling and root planning replacement of overhanging restorations and crowns with improper margins and contact areas extraction of periodontally hopeless and non-strategic teeth relief from "trauma from occlusion" by conservative selective grinding and use of occlusal splints. ď&#x201A;§ Pulpal

therapy:

endodontic

procedures

for

asymptomatic

and

symptomatic teeth with necrotic pulps.

44

ď&#x201A;§ TMJ disorders : orthopedic appliance therapy for conservative management of TMJ disorders.

8. ESTHETIC TREATMENT PLANNING AND SEQUENCING The definitive treatment plan should address the treatment period, expenses, treatment sequencing and all aspects related to the function and maintenance of the anticipated result.

Several treatment plans can be proposed to the patient for esthetic correction. A problem list is made related to the dentofacial problems enlisting individual solutions for individual problems and the impact on the overall outcome.

A completed "Smile Analysis Form" can be discussed after the patient has reviewed the radiographs with the dentist, to understand the patient's attitude and expectations.

S.No. Teeth Yes No In a slight smile, with teeth parted. do the tips of 1. your teeth show?

Are your two upper front teeth slightly longer than 2 the adjacent teeth?

3 Are your two upper front teeth too long?

4.

Are your two upper front teeth too wide?

5.

Are your upper six front teeth even in length?

6.

Do you have space between your front teeth?

7.

Do your front teeth protrude or stick out?

8.

Are your front teeth crowding or overlapping?

When you smile broadly, are your teeth all one 9. colour?

10.

Do your teeth have white or brownish stains?

If your front teeth contain tooth coloured fillings, 11. do they mater. the shade of your teeth?

12.

Is one of your front teeth darker than the others?

13.

Are your lower six front teeth straight?

14.

Are your lower six front teeth even in appearance?

In a full smile, the back teeth normally show. Are 15.

your back teeth free of stains and discolourations from unsightly restorations?

45

Do the necks of your teeth indicate erosion, a 16.

ditched-in "V", that either can be seen or felt with your fingernails?

When you smile broadly, does your top lip rise

17.

above the necks of your teeth so that your gums show?

18.

Do your restorations - fillings, laminated and crowns - look natural?

Gums

19.

20.

21.

Are your gums pink and "knife-edged", or are they red and swollen?

Have your gums receded from the necks of the teeth?

Does the curvature of your gums around each tooth create a half- moon shape?

Breath

22.

Is your mouth free from decay or gum diseases that can cause bad breath?

Treatment sequencing is an integral part of treatment planning. It is a phasewise distribution of treatment procedures, which will be programmed or charted

considering

periods

of

healing,

patient

convenience

and

interdisciplinary treatment modalities. The treatment sequence may change during the treatment, as some conditions may need to be reviewed or certain additional procedures may become necessary to get the desired result.

FINAL CASE PRESENTATION There are three basic methods to help patients visualize your suggested solutions: 1. Mock-up with soft tooth coloured wax or composite resin Direct composite resin placement along with the use of intra oral markers

46

can be beneficial in simple situations, since they provide a visual three dimensional means for the patient to see the final result prior to committing to treatment. The functional movements in the mouth can also be checked at this time to determine any potential in occlusal obstructions or difficulties.

2. Diagnostic wax ups on study casts Probably the best method and one that has stood the test of time is to prepare a diagnostic wax-ups and evaluate with the patient. This wax-up itself can be evaluated by the patient directly on the diagnostic casts of the articulator and also intraorally with the use of acrylic overlays and acetate matrices.

3. Computer Imaging: Digital imaging takes advantage of contemporary technology. In a particular case esthetic enhancement with a change of arrangement, form, shape and color can be demonstrated quickly. Thus it can be used as a quick reference which can guide future artistic creations.

PHYSIOLOGICAL/BIOLOGICAL CONSIDERATIONS How good is a new smile if it doesn't last? However pleasing a dental restoration may appear, if it is destructive to the biologic system, it is "ugly".

Form and function are intimately intertwined. The anterior region of the mouth presents a double challenge because it deals not only with the vital anterior guidance system, but also the most predominant area of esthetics. Both objectives must be-satisfied.

The safest sequence of treating a mouth to bioesthetic function is as follows: 3. Good diagnosis and treatment planning Patient education 4. Treating the periodontium 5. Stabilizing the craniomandibular relations in centric relation 6. Restoring anterior teeth to bioesthetic function Restoring posterior teeth to natural physiologic function

47

7. Regular post-treatment maintenance OCCLUSAL CONSIDERATIONS Tooth morphology is totally genetic and not specific to race or gender. Nature produces sharp tooth morphology on both anterior and posterior tooth surfaces, therefore it is necessary to have unworn crown morphology for good esthetics as well as function. Natural crown morphology of both anterior and posterior teeth develops early in life and is complete in every detail prior to tooth eruption into the oral cavity. However, the other components of the gnathostomatic system, including the joints, ligaments, muscles, maxilla, mandible and other cranial facial bones, continue to change significantly long after the occlusal morphology of the teeth is complete. These changing components, such as the temperomandibular joints, maxilla and mandible, are predetermined by genetics. The skeletal components, however, are subject to environmental modification by factors such as abnormal posturing of the mandible due to poor occlusion, face sleeping, abnormal swallowing, thumbsucking and other abnormal habits.

Natural and restored maxillary and mandibular teeth should have optimal functional contact relationship resulting in the even distribution of load in static and dynamic positions leading to minimal trauma of teeth and supporting structures.

48

Forces on the dentition The peri-oral musculature and the tongue exert a constant force on the teeth. In full occlusion, the lower lip and upper lip rest against the labial surface of the maxillary incisors. The lower lip helps retain the maxillary teeth against the mandibular anterior teeth while the tongue holds the mandibular incisors against the maxillary incisors in a state of equilibrium, referred to as the "Neutral Zone". This lip-tooth-tongue relationship helps produce a negative pressure seal during mastication and swallowing as well as stabilization of teeth positions.

Neutral Zone The direction and dissipation of load makes a difference in the forces exerted on the anchored root and the surrounding bone. The process of directing occlusal forces through the long axis of the tooth is called "Axial loading".

Vertical load causes less stress compared to lateral load. A thorough examination reveals that canines are best suited to accept horizontal forces during eccentric movements as they have the best crown-root ratio and dense compact bone around the roots.

The maximum biting force is in the range of 30-50 psi for the incisors, 47-100 psi for the canines and 127-250 psi for the molars.

Mandibular movements: The mandibular movements are influenced by the anatomy of the mandibular fossae and the condylar head, shape of the articular eminences, musculature as 49

well as the attachment and movement of the articular discs.  Functional movements: The functional movements occur during the functional activity of the mandible. They occur in all three planes. When the mandibular movements in all three planes i.e. sagittal, horizontal and vertical are combined, we get a three-dimensional "Envelope of Motion". The actual size of functional mandibular movement in the horizontal plane takes place within a small diamond shaped area, only 3mm to the right, left and forward.  Parafunctional movements.' are identified as a cause for occlusal wear and excessive forces. They can be related to local factors like malocclusion, to systemic factors like cerebral palsy, epilepsy and can also be stress and occupation related. Bruxism, clenching and parafunctional tongue-thrust are important parafunctions which the dentist should consider during the treatment planning stage.

Types of articulation  Balanced occlusion: this occlusion has all teeth contacting in all excursions. It is primary a denture occlusion. Naturally occurring examples are cases of advanced attrition.  Mutually protected/canine-guided occlusion: when the mandible is moved in a right or left laterotrusive excursion, only the maxillary and mandibular canines contact and efficiently dissipate the horizontal forces while disoccluding the posterior teeth. Canines are best suited for this as they have large roots, dense surrounding bone and trigger fewer 50

muscles during eccentric activity, decreasing forces to the dentition and the TMJ. ď&#x201A;§ Group function: there are contacts between the maxillary and mandibular teeth on the working side in eccentric movements. The nonworking side completely disoccludes. This is the most favourable alternative to canine guidance in case the canine is unavailable or periodontally compromised. The most desirable group function consists of the canine, premolars, and sometimes, the mesiobuccal cusp of the first molar.

Centric relation Is defined as the completely retruded position of the mandible with the condyles in their most superior anterior position at any vertical rotational position of the mandible.

CR has been found clinically to be the best location for maximum intercuspation of teeth. In good occlusion, all teeth in the mouth (anteriors and posteriors) make simultaneous contacts. Anterior teeth should never contact harder than the posteriors or fremitus may be produced with possible endodontic and periodontal trauma and/or interproximal separation of teeth.

Normally, occlusal contacts on the anterior teeth in CR are not broad, but rather two or three spots per tooth on the incisors and one on each canine. The total contact area has been estimated to be about 4mm for the entire mouth, including all of the anterior and the posterior teeth.

Stabilization of the craniomandibular relation in CR is important to the comfort, function and longevity of dental restorations. .

51

Contacts on the anterior teeth in maximum intercuspation should average about two for each tooth Anterior overbite The maxillary anterior teeth are normally positioned labial to the mandinbular anterior teeth. Both maxillary and mandibular anterior teeth are inclined in a labial direction ranging 12 to 28 degrees from a vertical reference line.

In well-related teeth, the vertical overbite of the maxillary central incisors ranges from 4-5mm when the teeth are in full occlusion. The horizontal overbite of the maxillary incisors is 2-3mm in full occlusion

Overjet and overbite Variations can result from different developmental and growth patterns. ď&#x201A;§ When a person has an underdeveloped mandible (class II molar relationship), the mandibular anterior teeth often contact at the gingival third of the lingual surfaces of the maxillary teeth (deep overbite). ď&#x201A;§ In persons in whom there may be pronounced mandibular growth, the mandibular anterior teeth are often positioned forward and contact with the incisal edges of the maxillary anterior teeth (molar class III 52

relationship). This termed in edge-to-edge relationship. ď&#x201A;§ Another anterior tooth relationship is one that actually has a negative vertical overlap. In other words, with the posterior teeth in maximum intercuspation the opposing anterior teeth do not overlap or even contact each other. This anterior relationship is termed an anterior open-bite. In a person with an anterior open-bite there may be no anterior tooth contacts during mandibular movement (Fig.5, 6, 7) Anterior guidance Is the dynamic relationship of the lower anterior teeth against the upper anterior teeth through all ranges of function. It literally sets the limits of movement of the front end of the mandible.

Anterior relationships must be determined with extreme preciseness because along with the discomfort and look of artificiality, improperly restored anterior teeth may contribute to the destruction of the entire dentition. When their position allows it, anteriors should be made to form a very stable stop for the front of the mandible, thereby limiting its closing motion.

Anterior guidance is of two types: ď&#x201A;§ Incisal guidance (in protrusive-retrusive movements) : its primary importance is for proper incising as well as rest positions and speaking functions. ď&#x201A;§ Canine guidance (in mediotrusive lateral movements) : the primary importance of the canine guidance is to help prevent lateral eccentric posterior tooth interferences and allow the condyles to move uninhibitedly along their border pathways in the fossae as well as to guide jaw closures more vertically to load the posterior teeth in their long axis.

PERIODONTAL CONSIDERATIONS A healthy periodontal environment with sufficient tissue volume to fill the interproximal spaces is an essential element for ideal anterior esthetics. The 53

tooth shape, incisogingival length, mesiodistal width and the contact areas guide the gingival position in natural dentition.

Biologic width Gargiulo et al demonstrated in human autopsy specimens, a proportional dimension relationship between the dentogingival junction and the other toothsupporting tissues. The mean sulcular depth was O.69mm, the mean length of the junctional epithelium was O.97mm and the connective fibrous tissue attachment was 1.07mm (with a range of 1.06-1.08mm). Of these three tissue components, the supracrestal connective fibrous attachment exhibited the least variability. The combined width of the connective tissue attachment and the junctional epithelium averaged 2.04mm and has been called the "Biologic Width".

Biologic width The importance of not violating this physiologic dimension was suggested by Ochsenbein and Ross and stressed by other authors. When margin placement impinges on the biologic width, gingival recession or pocket formation and periodontal disease may ensue, depending on the thickness of the keratinized gingiva and the underlying bone. Invasion of the biologic with may result in apical migration of the dentogingival unit with gingival recession and may be self-limiting. With relatively thicker bone, it may result in apical migration of the epithelial attachment and pocket formation.

54

ESTHETIC TREATMENT MODALITIES ESTHETICS WITH BLEACHING: Bleaching is an age-old treatment, which has been performed over a century. The current trend towards cosmetic dentistry has generated more interest in bleaching as patientsâ&#x20AC;&#x2122; desire whiter and more beautiful teeth. Our society tends to dislike yellowing of teeth that comes with age or by various stains.

White teeth are not only considered beautiful but are also indicative of nutritional health, self-esteem, hygiene pride and economic status.

Discoloured teeth on the other hand have far reaching effect on an individual both socially and psychologically.

Bleaching can be defined as the whitening of a tooth through the application of chemical agents to oxidize / reduce the organic pigmentation in the tooth.

Bleaching is one of the most commonly sought elective dental procedures to brighten a smile. It is a purely cosmetic treatment, which can even be performed by the patient under the guidance of the dentist. It is a simple, fast and effective treatment to change darker tooth shades into lighter ones.

Although this procedure is most non-invasive, it works wonders for the acceptance and self-confidence of the patient as it is appreciated through an immediate visual impact. Once considered the province of a few pioneering specialists in esthetic dentistry, bleaching has now moved into the main stream of dentistry.

In furtherance, bleaching when used as an adjunct to other cosmetic procedures such as enamel micro abrasion, veneers or crowns, helps to accomplish better esthetics with brighter smiles.

55

In many people an attractive smile is marred by some discoloration or stain, either on a individual tooth or on all teeth.

The dentist should be able to diagnose and treat various discoloration.

Different types of stains: Extrinsic

Intrinsic

Coffee and tea stains

Tetracycline stains

Cigarettes

Fluorosis

Diet

Trauma to tooth

Tobacco

Systemic conditions

Poor oral hygiene

-

Jaundice

-

Amelogenesis imperfecta

-

Erythroblatosis foetalis

-

Enamel hypoplasia

-

Iatrogenic

56

Common Discolorations and Associated Causes TOOTH DISCOLORATION ASSOCIATED CONDITION Yellow

Aging Calcific metamorphosis Loss of vitality Tetracydine ingestion Amoxicillin syrup Stannous fluoride Imipenem for cystic fibrosis Amelogenesis imperfecta

Opaque

Fluorosis Sickle cell anemia Osteogenesis imperfecta

White

Fluorosis Chronic kidney failure Hypomineralization

Brown

Fluorosis Smoking Coffee Soy sauce Cola Tea Calcific metamorphosis Loss of vitality Chlorhexidine ingestion Iron Tetracydine ingestion Antitartar toothpaste Osteogenesis imperfecta Chlorhexidine glucamate (Hibitane) disinfectant Tannic acid

57

Ochronosis Dental materials Black

Occupational: glass blowers Betel nut chewers Pipe/cigar smokers Dental materials (pins) Caries

Blue

Tetracvcline ingestion Osteogenesis imperfecta

Green

Hyperbilirubinemia Congenital biliary atresia Occupational: brass factory Marijuana smoking Nasmyth's membrane

Orange

Poor oral hygiene Chromic acid fumes

Red

Internal resorption Congenital erythropoietic porphyria Periapical granuioma in lepromatous leprosy Death

Gray

Tetracydine ingestion for cystic fibrosis Minocycline for acne in adults Dentinogenesis imperfecta Amalgam restorations Cyclosporine

58

Chemistry The bleaching process is based on an oxidation-reduction reaction. Hydrogen peroxide undergoes reduction and oxidizes the stained tooth structure to change its appearance. Oxidation is the chemical process by which organic materials are converted into carbon dioxide and water.

Bleaching slowly transforms the organic substance in the stained tooth into chemical intermediates that are lighter in color than the original tooth shade. In a redox reaction the peroxide (oxidizing agent) has free radicals with unpaired electrons, which it gives up, becoming reduced. The stained tooth structure accepts these electrons and becomes oxidized thereby reducing the organic colorants: The free radicals produced by the peroxides, are perhydroxyl and nascent oxygen. Of these, the perhydroxyl is a more potent free radical which is responsible for a better bleaching action.

In order to promote the formation of perhydroxyl radicals, the peroxide is buffered to a pH range of 9.5 to 10.8. The buffering provides a greater amount of perhydroxyl free radicals, which results in a better bleaching effect.

The most common bleaching materials used are hydrogen and carbamide peroxide. Carbamide peroxide first breaks down into hydrogen peroxide which then further liberates the above mentioned free radicals. Un like the hydrogen peroxide, the carbamide peroxide bleaching agent must remain in contact with the teeth for a longer period of time to obtain complete efficiency of the reaction. Carbamide peroxide is less irritatiog to the gingival tissues thus better tolerated by the patients when used as a home bleaching agent.

Mechanism of bleaching The hydrogen peroxide diffuses through the material into the tooth enamel. The free radicals produced have unpaired electrons, they are unstable and hence will attack most other organic molecules to achieve stability.

59

This results in reduction of the absorption energy of organic molecules in the tooth enamel, releasing the colorants thus creating a successful whitening action .

In the presence of moisture as well as surface debris on the tooth, the ionization of hydrogen peroxide occurs by decomposition into water and nascent oxygen which is a weak radical making the peroxide inefficient as a bleaching agent.

Hence, it is important to have teeth dry and free of surface debris when applying the bleaching agent. This can be achieved by proper oral prophylaxis prior to bleaching. Increase in the temperature, higher peroxide concentration and the duration of exposure of the tooth structure to the peroxide within limits, directly affects the oxidation process leading to a greater degree of color change.

Saturation point: Prolonged use of a bleaching agent causes the whitening action to slow down beyond a point during the treatment. This is the saturation point. The bleaching if allowed to continue, begins to break the inorganic structure from the enamel matrix and the loss of enamel, becomes rapid.

Bleaching should thus be stopped at or before the saturation point.

Optimal bleaching gives maximum whitening, while over bleaching degrades tooth enamel. Although this parameter is difficult to judge, the patient should be instructed to stop bleaching when they see no significant change in the shade on subsequent bleaching applications.

If bleaching is done beyond the saturation point, it clinically manifests an increase. in porosity on the tooth surface. A fluoride application is recommended and no bleaching agents should be applied allowing the enamel to remineralise.

60

Oxidation process associated with bleaching teeth

61

Case Selection As a rule of the thumb, extrinsic stains are better managed by bleaching as compared to the intrinsic stains. A large part of the success of bleaching lies in judicious diagnosis and case selection. Not all cases of discolored teeth are ideal candidates for dental bleaching. Management of dental decay, enamel loss and periodontal pathosis is a prerequisite to bleaching. Cases showing severe enamel loss, fluorosis leading to mottling of enamel and developmental defects in enamel formation are contraindicated for bleaching.

Non-vital teeth that have discoloured as a result of trauma can be successfully bleached, but those with other intrinsic stains such as amalgam or remineralised lesions will be more resistant to colour change. Teeth with minor restorations on the buccal surface or, ideally, those with only an access cavity are the most successfully bleached. Teeth with extensive restorations are usually more effectively crowned.

Preparation for bleaching 1) Record keeping and photographs â&#x20AC;&#x201C; Record keeping should begin at the treatment planning stage. Records should document decision for treatment and alternative. It is absolutely essential to take adequate photographs of a patients preoperative condition. No amount of description can exactly depict, how the patient looked before treatment. In addition, photographs are more reliable than memory in documenting the progress of treatment.

2) Careful diagnosis, using radiographs and transilluminating techniques : In this, the possibilities of any periapical abnormalities can be ruled out.

Caries and decalcified or hypocalcified areas will be disclosed. The size and vitality of the pulp can be determined and the opacity, depth and layers of

62

stains can be defined. Also, hypersensitivity of the teeth should be ruled out.

3) Oral prophylaxis and polishing with sodium bicarbonate : to rid teeth of all surface stains, plaque and calculus. The patient should be protected with heavy plastic wrap and safety glasses. In most cases, anaesthetic must not be used. Rather, then patient should be able to tell the dentist if leakage occurs as the heat becomes too intense. All members of the dental team should wear protective eye wear, surgical rubber gloves and masks.

4) Preparation of teeth to be bleached. Isolation with: a) Rubber dam. b) Protective paste-Orabase or Vaseline applied to soft tissues. c) Gauze saturated with cold water placed under rubber dam. d) Pumice used to remove excess stain or protective paste. e) Floss is ligated interdentally to prevent seepage of the bleaching solution into the gums.

Application of Orabase/Vaseline

63

Rubber dam of heavy gauze is used Punched holes â&#x20AC;&#x201C;smaller in size

Stabilization in the cervical areas with dental floss

Bleaching is of two types: a) Vital Bleaching b) Non-vital bleaching.

BLEACHING OF VITAL TEETH

There are at least three ways of bleaching vital teeth.

1)

In office bleaching or power bleaching techniques:

64

a)

Thermocatalytic method

- Light

- Heat b)

McInnes solution

- Old

- New 2)

Night guard vital bleaching.

3)

Over the counter preparation.

1. In office bleaching / Power bleaching - First vital bleaching technique.

- ADA products ADA accepted Superoxol (Sultan Chemists) Starbrite in office bleaching.

a) For tetracycline stains -

Teeth are covered with gauze saturated with 35% H2O2. (Fig. 1)

-

The peroxide solution may be activated by heat or light.

-

Bleaching light positioned 13 inches from the teeth with the light shining directly on them. A rheostat setting of 5 usually used. (Fig. 2)

-

Where heat is used a temperature setting of 46-60째C for vital teeth.

-

The gauze should be kept wet by dispensing fresh bleaching solution with a cotton swab. (Fig. 3)

65

-

The bleaching agent should be kept in contact and light/heat applied to the teeth for 30 minutes.

-

Excess solution rinsed off with copious amounts of warm water. Brush and then polish.

-

At one time, it was considered to etch the teeth with phosphoric acid before bleaching, supposedly to enhance the effect. However, etching is not actually necessary.

-

Tetracycline stains generally requires 5-10 visits. Best scheduled every 2-4 weeks.

Wet the gauze

Apply saturated gauze to labial surface (Fig. 1)

66

On lingual surface Protection lenses for the pt

Keep the light about 30 cms (13 inches) from the teeth and direct the beam to the surface to be bleached temperature ranges from 115째-140째F. (Fig. 2)

Add new solution at every 4 to 5mins (Fig. 3)

Removal of dam, wiping, rinsingand neutralisation with Na gel b) For fluorosis stains 67

-

Because fluorosis stains causes much more heterogenous pattern of staining, the bleaching method is more selective.

-

Bleaching agent â&#x20AC;&#x201C; Old / New McInnes solution

(Acidic medium) Old McInnes Ratio Bleaching enamel Etches enamel Removes surface debris

-

a) 30% H2O2

5 parts

b) 36% HCl

5 parts

0.2% ether

1 part

Alkaline medium) New McInnes Ratio 30% H2O2

1 part

20% NaOH

1 part

After pretreatment procedures are carried out cotton applicators carrying fresh bleaching agent applied for 5 minutes and repeated after an interval of 1 minute.

-

Application was repeated till the desired bleaching effect was observed.

-

With Old McInnes solution the solution was neutralized with baking soda.

-

Warm water is flushed on the enamel before rubber dam is removed.

-

Polishing is done to achieve a high enamel luster.

Disadvantages: 1)

Repeated isolation is a problem.

2)

Power bleach only can be applied on anterior teeth.

3)

35% H2O2 is caustic and should avoid burning themselves or patient.

68

4)

Discomfort during and sensitivity for a week after treatment.

5)

No reliable way of predicting success.

2) Night guard bleaching (NGVB, dentist prescribed home applied technique, dentist home bleaching or matrix bleaching).

-

Introduced by Haywood and Heymann in 1989.

-

Custom fitted prosthesis filled with 10% carbamide peroxide is worn for few hours each day for a few weeks.

-

Carbamide peroxide composed of approximately 3% H2O2 and 7% urea.

H2O2 degrades into H2O2 and O2 while urea degrades into ammonia and CO2. All these materials occur naturally in the body and are easily managed. Usually 10% carbamide peroxide solution was used.

-

Lesser concentration of carbamide peroxide (5% instead of 10 and 16%) can also be used. They take longer time but may lead to less sensitivity as compared to the higher concentration solutions.

-

Carbopol (B.F. Goodrich) is added to this solution to make it stickier, and prolong the oxygen release. This type of material favours overnight wear.

-

For patients who find it uncomfortable to wear it overnight, they are advised to place it 2-4 hours before sleeping. Disadvantage is that the treatment time is prolonged.

69

ADA accepted bleaching products for NGVB -

Colgate Platinum Overnight Professional Tooth Whitening system.

-

Nite White classic.

-

Opalescence whitening gel.

-

Patterson Brand tooth whitening gel.

-

Rembrandt Lighter bleaching gel.

3) Over the counter bleaching systems (eg: perfect Smile System) -

Shortly after the dentist home systems were introduced, several systems were sold directly to the consumers.

-

Also called ‘home bleaching’ systems but are more appropriately referred as OTC home bleaching systems.

-

Some of the earlier systems have a 3-step procedure.  an acidic pre-rinse.

70

 application of a lower strength peroxide material without a prosthesis.  a final application.

-

Later developed were home systems which use same strength of bleaching solution as the dentist home system but apply the material with a “boil and form” mouthguard.

Enamel Microabrasion Technique One of the relatively new techniques for removal of stains in endemic fluorosis cases is the use of enamel microabrasion technique.

In 1916, Dr. Walter Kane, of Colorado Springs, used 18% hydrochloric acid with a warm instrument to successfully remove stains associated with endemic fluorosis. Since 1916, numerous investigators have used hydrochloric acid alone on fluorosis stains. In 1984. Mc Closkey described Kanes work and demonstrated successful cases of his own. He found that brown fluorosis stains can permanently be removed by rubbing the enamel with an 18% HCl acid soaked cotton pellet wrapped around and amalgam condenser.

Two years later Croll and Cavananaugh developed a similar technique that involves pressure application of 18% HCl with pumice to achieve colour modification. This was called the enamel microabrasion technique. The chief mechanism of stain removal would be limited to enamel abrasion, rather than enamel dissolution by the acid. Dr. Croll believed that the acid abrasive action of the compound gives the enamel surfaces, a super fine polishing as a microscopic layer of enamel is removed. The freshly polished surface then develops a shiny glass like texture, resembling a highly polished microfilled composite resin restoration, as the tooth subsequently remineralized.

Jacobsson-Hunt (1988) reported 30-second applications of the acid abrasive compound using a mandrel and gear reduction handpiece on extracted

71

human teeth results in a enamel loss of less than 200Âľm. In 1989 Kendell reported that 5 second application of HCl acid pumice mixture removes 46Âľm of enamel which should be considerably tolerated.

An important concern about the safety of the hydrochloric acid pumice abrasion procedure is the low viscosity and high concentration of 18% HCl. To eliminate this problem and ensure safety of this technique, the viscosity of the acidic solution is increased by mixing 18% HCl acid with quartz particles so that the solution takes on a water soluble gel like form. This came to be known as the modified 18% HCl acid quartz-pumice abrasion technique.

The procedure is as follows: 1.

The gingiva was protected by a layer of petroleum jelly.

2.

The involved teeth were isolated with rubber dam.

3.

After the teeth were dried with air, the paste which consisted of 18% HCl acid quartz-pumice particles, was applied with a cotton tip applicator to the stained areas of enamel.

4.

The paste was allowed to remain 5 seconds and then for 10 seconds, the enamel microabrasion was effectuated with a cotton swab pressure.

5.

After 10 seconds, a marked degree of success was obtained and the stain was removed.

6.

After 15 seconds of treatment, the enamel of the teeth turned to a normal shade.

7.

At the end of the treatment, the teeth were washed and dried before removal of rubber dam was neutralized with a neutral sodium gel.

72

In this procedure, the quartz particles convert the acid into a gel form and functions as an additional abrasive agent. Six months following this treatment on several patients showed that the objectives of the treatment was achieved.

The advantage of this technique is that it is relatively economical, involving no laboratory costs, making this technique readily acceptable to children.

73

BLEACHING OF NON-VITAL TEETH Preparation of the affected non-vital teeth: 1)

In office bleaching.

2)

Out of office bleaching (walking bleach technique).

3)

Other bleaching techniques.

-

Isolation is done with a rubber dam.

-

The tooth is meticulously cleaned internally.

-

Establish a lingual opening of sufficient size to provide access to the pulp chamber and orifice of the root canal.

-

A slowly rotating bur is used to remove debris and a surface layer of dentin within the pulp chamber.

-

In endodontically treated teeth, root canal filling material should be removed to a depth of 2-3mm apical to the cervical line.

-

Zinc polycarboxylate cement, cavit or zinc oxyphosphate cement can be used to refill, 1-2mm coronally to the CEJ. Bleaching should never be attempted on any tooth that does not have a

complete seal in the root canal. The agent could escape through a porous root canal filling and cause the patient extreme discomfort as well as probably loss of tooth.

-

Surface stains visible on the inside of the preparation are removed, the entire preparation is swabbed with chloroform or acetone to dissolve any fatty material and facilitate the purification of the bleaching agent into the tubules.

1) In-office bleaching (Thermocatalytic techniques)

74

-

The pulp chamber is filled loosely with cotton fibres and the labial surface is covered with a few strands of cotton fibre to form a matrix for retaining the bleaching solution.

-

This is saturated with 35% H2O2 using a glass syringe fitted with a stainless steel needle. The solution should be discharged slowly to saturate the cotton inside the pulp chamber and on the labial surface excess should be wiped immediately.

-

A thin tapered tip from a single tooth bleaching instrument can be inserted into the pulp chamber. The heated tip is exposed for 5 minutes, in a sequence of 1 minute on 15 seconds off.

75

-

It has been established by Caldwell that a non-vital tooth can be treated to a temperature of 73째C without causing the patient discomfort.

-

An alternative to activate the H2O2 is the use of light and heat from a heat and light bleaching powerful light. The tooth is subjected to 6, 5 minute exposures and one replenishes the bleaching agent at frequent intervals.

-

The heating instrument and cotton can then be removed. Repeat the above process 4-6 times or for 20-30 minutes each time placing new cotton fibres.

-

This technique can be used alone or in combination with walking bleach.

76

2) Out Office bleaching (Walking bleach) -

First described by Nutting and Poe in 1963.

-

This procedure consists of filling the prepared chamber (as described previously) with a paste consisting of 35% H 2O2 and sodium perborate. (their effect is thought to be synergistic).

-

Sodium perborate is a white powder which decompose into sodium metaborate and H2O2 releasing O2. When mixed into a paste with Superoxol, this paste decomposes into sodium metaborate, water and oxygen.

-

When sealed into the pulp chamber, it oxidizes and discoloures the stain slowly, continuing its activity over a longer period.

77

-

A small pledget of cotton wool is placed on the paste and the cavity is sealed with polycarboxylate cement kept under pressure till the cement sets.

-

The maximum bleaching is attained 24 hours after treatment.

-

The patient should return in 3-7 days.

-

If shade - dark then repeat procedure - light then permanent restoration with silicate or GIC.

-

Generally two treatment sessions although in some cases one treatment is sufficient.

3) Other methods of non-vital bleaching a) Inside-outside bleaching (Leonard and Stettembrim et al 1997) -

Fabrication of a study model.

-

Light cured composite is placed on the model of the tooth or teeth to be treated. This acts as a reservoir to be created in a vacuum processed mouthguard whose thickness usually varies from 0.20 and 0.30 inch.

-

Mouthguard trimmed at the cervical margins on the labial and lingual portions and tried in the patients mouth.

78

-

The GP is the root canal is sealed off from the pulp chamber with GIC or resin modified GIC.

-

Patient is taught how to inject 10% carbamide peroxide into the canal orifice and into the mouthguard with a syringe.

-

Excess CP gel can be removed by brushing or using a paper tissue.

-

The patient may either sleep with the gel or remove the mouthguard after 1 or 2 hours. If the patient prefers the latter, it will take a few days longer.

-

At the end of the daily treatment, patient rinses his or her mouth and then places a cotton pellet to prevent food from getting into the opening.

-

An explorer can be used by the patient to remove the cotton pellet before the next procedure.

-

The total treatment proceeds and rapidly concludes with the results in as few as 3 or 4 days.

b) Anderson Takeo Hara, and L.A.F. Punenta (1999) (suggested by Spassier) used a technique where sodium perborate and water was used as a walking bleach technique instead of H2O2 to prevent cervical resorption. Sodium perborate broke down to sodium metaborate and H 2O2. Two year results were satisfactory with this technique. c) Laser assisted bleaching -

One company uses the argon laser wavelength of 488nm for 30 second to accelerate the activity of its bleaching gel. After the laser energy is applied, the gel is left in place for 3-4 minutes then removed.

This procedure is repeated 4-6 times.

-

Another product uses Ion Laser Technology. The argon laser is used as previously described. Then the CO 2 laser is employed 79

with another peroxide solution to promote penetration of the bleaching agent into the tooth to provide bleaching below the surface.

-

Argon laser energy is in the form of a blue light and is absorbed by the dark colour. It seems to be the ideal instrument to be used in tooth whitening when used with 50% H2O2 and a patented catalyst.

The affinity to dark stains ensures that the yellow-brown colours can be easily removed.

-

The CO2 laser has no colour requirement. It is unrelated to the colour of the tooth and the energy is emitted, in the form of heat. It is invisible and penetrates only 0.1mm into water and H 2O2, where it is absorbed. This energy can enhance the effect of whitening after the initial argon laser process.

Post bleaching instructions: -

Avoid food or liquid that may stain the tooth structure.

-

Maintain proper fluid intake to cope with dehydration of tooth surface.

-

In case of severe sensitivity, discontinue the procedure until the symptoms subside.

CONTRAINDICATIONS OF BLEACHING TOOTH Bleaching should not be advised when the pertinent tooth has:

80

1. Cracks and hypoplastic or severely undermined enamel.

2. Extensive silicate, acrylic or composite restorations.

-

These teeth may not have enough enamel to respond properly to bleaching.

3. Discolouration by metallic salts, particularly silver amalgam, the dentinal tubules can become virtually saturated by these alloys causing stains that no amount of bleaching can significantly improve.

4. Enlargement of the pulp or other disease that makes the tooth sensitive to bleaching solutions or may require special care and desensitization.

ADVANTAGES 1. Safe procedure.

2. Painless to adults.

3. No tooth reduction required.

4. No anesthetia necessary.

5. Least expensive of treatment alternatives.

DISADVANTAGES 1. Normal tooth color may not be restored.

2. Bleaching can cause discomfort in children because of their large pulps 3. Only 75 percent effective in selected cases.

4. Extended treatment time may be necessary.

Complications: 1.

Cervical resorption

81

-

Possible mechanism is that H2O2 percolates from the access cavity to the root surface through the acid treated patent dentinal tubules.

-

This stimulates an inflammatory response tending to dentin resorption.

-

Alternative theory â&#x20AC;&#x201C; bacteria that have leaked into the pulp chamber from the gingival crevice via the dentinal tubules or directly from the access cavity may cause resorption.

-

Root resorption can be arrested by placing CaOH in the chamber.

2.

Spillage of bleaching agents -

Oxidizing agents are more safe to handle as a paste than a solution.

-

Apply rubber dam.

-

Any spillage must be diluted immediately with copious volumes of water.

3.

Failure to bleach

-

Commonest is discolouration by metal ions in silver amalgam.

-

Incomplete removal of composite resin or GIC which prevents the bleaching agents to penetrate into dentinal tubules.

-

H2O2 which has passed its expiry date or improperly stored.

4.

Over bleaching

-

Recommended since it may darken with time an assume desired shade.

-

Important not to over bleach therefore ask the patient to monitor and return in case of over bleaching.

5.

Brittleness of tooth crown

82

-

Bleaching causes the coronal tooth structure to be brittle. This may be caused due to removing all the discoloured dentin rather than using the bleaching agents to discolour the dentin.

83

ESTHETICS WITH COMPOSITES The conservative treatment approach is best collaborated with the use of composites due to their ability of bonding to many surfaces including natural teeth. This has opened up many avenues for the use of these materials for esthetic benefits in cases that probably could not be treated effectively or at all in their absence. The results with this material are quick, esthetic and economical, repairs are easy and the material per se does not call for unnecessary tooth reduction for its effective placement. In most instances, the final results are all in the control of the dentist without the involvement of laboratory technicians thus providing the dentist an opportunity to exhibit his skills and finesse.

Considerations in preparation design for anterior teeth The adhesion of composite resin to the tooth is the differentiating factor in the preparation design as against the conventional designs used predominantly for mechanical retention of materials. The multiplicity of use of composites in disparate situations deters the standardization of the preparation design.

Though the preparation designs for composite resins do not follow a prescribed pattern they are essentially made as conservative as possible, leaving as much enamel as permissible for effective bonding. This is done keeping desired final esthetics of the restorations in mind.

The preparation design for anterior composite restorations should encompass elimination of decay, function and longevity, and esthetic predictability

84

Elimination of decay The cavity design is mainly governed by the extent of the decay. The gross caries is removed using a round bur and any residual soft caries excavated thoroughly to leave behind a hard tooth structure. The caries indicator helps the dentist to identify areas of active caries. Anti-microbial agents used separately or along with the etchants help to eliminate bacterial contamination remnant at the base of the cavity.

Function and longevity A preoperative analysis of the occlusion is crucial to determine the palatal extensions and the acceptable length in upper anterior restorations. Checking the lateral and protrusive excursions will give an idea as to how far palatally the final restoration can be placed. Sometimes the lower incisors may also need to be altered before restoring the upper teeth. Enamel may have to be beveled to increase the surface area available for bonding in some preparations. A 45째 bevel is most commonly used to expose more enamel rods for stronger bonding, to take away unsupported enamel prisms and to enhance color blending of the restoration with the tooth.

Researchers have found that a minimum of 1.5mm - 2mm of the composite thickness is essential to give sufficient strength to the material. A conscious effort has to be made to leave at least 2mm of composite thickness at the margins for good marginal adaptation and retention in larger restorations.

Hybrid or spheroidal composites are used in areas subjected to functional forces like incisal edges, proximal contact areas and the palatal aspect of the upper anteriors

85

Esthetic Predictability After elimination of the decay and determining the extent of preparation required, for function and longevity, the preparations are evaluated and if required redefined. The preparation design is extended to allow a smooth transition of shade from the composite restoration to the rest of the tooth. This enables the restorations to achieve esthetic excellence.

To create proper tooth form, shape, shade and texture, and to optimize function, all cavity preparation designs should have extension for function and esthetics (EFE). The facial form of all anterior teeth can be divided into various facial planes, which converge or diverge from each other. These planes reflect or refract light and give a texture to the facial surface. The areas between any two planes are relatively prominent and hence extension of the margins of the preparation should be kept away from these prominent areas. Extension for functional esthetics (EFE) is achieved using a long bevel extending a few mm. from the cavity margin arid ending on a relatively flat area on one of the planes.

The EFE ensures that the margin of the restoration overlays the defects. The esthetic advantages are: •

Successful masking of the defect.

•

Better marginal adaptation.

•

Natural transition of shade between composite and tooth.

•

.Ease of finishing and texturing. .

The EFE is usually prepared using a long tapered fissure bur on the labial aspect to make a bevel and a chamfer bur on the lingual and proximal aspects to make a chamfer. The preparation designs will differ in various clinical situations like carious lesions fractured teeth, malposed teeth, discolored teeth, and closing spaces and in areas of abrasion or abfraction etc. depending upon

86

the esthetic requirement.

Placement of composite for carious teeth When the caries involves the labial surface the EFE follows the general guidelines explained earlier following the facial planes .However, in cavities with palatal access, leaving a thin shell of enamel of the facial surface is not recommended as it is difficult to blend the composite restoration with the rest of the tooth. In such cases, the labial unsupported enamel is reduced and the composite is extended on the facial surface. If the carious lesion is large, then a full facial veneer preparation may be the best option for optimal esthetic results.

During the placement of composite in the proximal areas, a mylar / metal strip is placed between the preparation and the adjacent tooth while acid etching and bonding. A small amount of flowable composite is placed along the walls of the cavity and then cured. A layer of an opaque hybrid composite is placed more on the palatal half of the restoration and also in conditions where the palatal wall is absent. This blocks the path of light waves passing through and through, giving a grey translucency to the restoration. This ensures adequate translucency in the final restoration. The desired shade of composite is then placed in increments and cured. Micro filled composites are used as the last layer to get the desired result in the restoration which is finished and polished.

87

Composite Restoration of a carious tooth

Caries on the mesial aspect of the internal incisor. The palatal portion is intact

Prepared cavity design with a bevel for functional longevity and esthetic predictability.

Marked areas shows the smooth transition of the bevel with the normal tooth surface which aids proper blending of composite

Etching for 15-20 seconds with 32% ortho-phosphoric acid with antimicrobial agent

Three coats of bonding agent applied

Flowable composite used as an intermediate layer and cured for 20 seconds

88

Curing carried out of 20 seconds after final placement of composite

Gross finishing and defining of the margins with a finishing diamond bur

Intermediate finishing with silicone disk

Interdental polishing strips used to contour the proximal area

Final polishing with aluminum oxide or fine diamond polishing paste

Finished final restoration in an air-dried field to demonstrate the blending at the composite-toothinterface

89

Placement of composite for fractured teeth The extent of the fracture and the thickness of the remaining tooth usually determine the EFE. The incisal edges in natural teeth are relatively thin, translucent and if reproduced effectively can make the restoration "life-like". In cases of smaller incisal fractures, the EFE should be labial as well as palatal. This allows an overlay of the composite from the labial to the palatal. This restoration can be referred as a 'palatal wrap-around' restoration.

In cases of fractures involving more than one third of the labial surface, the fractured portion is extended into a full veneer preparation design. A suitable palatal extension is given in the preparation design to allow palatal adaptation of the composite and create a more functionally stable restoration. After initial etching and bonding, opaque hybrid composite is placed on the palatal portion of the missing part of the tooth. The palatal extension is filled with hybrid composite, while a microfilled composite is used on the labial surface. The incisal and the labial aspect are finally restored with transparent incisal composite. In fractures involving the proximal areas, care should be taken to restore a proper contact with the adjacent tooth which reduces the stress on the restoration during masticatory dynamics.

Minor malalignment can be corrected with minimal. Reduction of tooth structure by changing .the tooth form in the preparation design to allow the composite restoration to recreate the desired form. In some of these cases the preparation design resembles the one made to treat minor fractures. However, when malaligned teeth have carious lesions, discolorations or deficiencies in proportions etc. a composite veneer is advised. The EFE for the veneer can be only on the labial surface, but when the length of the teeth has to be altered, then a palatal extension is required.

Multiple malaligned teeth are viewed in totality and then individually. The most difficult tooth to be treated is marked and may be the ultimate guide on which the 90

corrective treatment can be based, as it gives an idea of the limitations within which the dentist has to give an esthetic final result.

The preparation in malaligned teeth is atypical and depends upon the degree of rotation and angulations exhibited by the teeth and hence a uniform layer of composite cannot be placed to treat such teeth. The effective use of opaque composites in areas having no tooth or thin palatal structure, improves the blending of the restoration. Creating surface characteristics and effectively placing the transitional angles on the facial surface can help to overcome deficiency in tooth reduction.

Composite Restoration of a fractured tooth

Before

After composite

Placement of composite for closing spaces Diastemata may be manifested due to microdontia, discrepancy between tooth size and the available ridge and also due to variation in the tooth morphology.

Although some natural spaces may be esthetically and phonetically acceptable, others are not and need corrective restorative procedures. However, in cases where the size of the teeth is normal and a diastema still exists, restorative creations using principles of illusion is recommended.

Boundaries of the space are assessed apico-coronally and mesio-distally, as they will differ with the location of the interdental papilla and the proximal contours of teeth. In periodontally treated cases there could be papillary loss resulting in a black triangle effect. Thus closing spaces in such cases may pose a challenge as 91

the dentist will have difficulty to maintain the tooth form, tooth proportions, as well as allow good gingival contours for favorable gingival response. Sometimes an excessive frenal tissue makes it difficult for the dentist to restore this area and a frenectomy may be advised in some cases.

When a diastema is small up to 2mm, no tooth preparation is required. The minimal thickness of composite can be adequately shaped especially at the cervical region to allow good maintenance. However, in cases of a moderate diastema between 24mm the EFE should be given on the proximal curvature of the labial surface of the tooth. The extension preparation is close to the gingival margin and follows the contour of the interdental papilla to end on the palatoproximal line angle. The preparation is in the form of a depression, which provides a definite stop and is done with a chamfer bur. The preparation design ensures adaptation of sufficient bulk of the composite at the gingival margin creating contours favorable for gingival health. The labial extension allows smooth blending at the composite-tooth interface while the palatal extension provides stability and retention. The composite can then be easily contoured from the prepared area to the incisal edge. In cases with diastemata larger than 4mm a similar preparation coupled with recontouring of the other proximal surface of the tooth to maintain tooth proportions and form may be required.

Diastemata are filled in one tooth at a time. A celluloid matrix is effectively used to get the desired contour. In the diastema, opaque composites are used to build up a palatal wall followed by placement of hybrid composites of the desired shade on the palatal and cervical aspect of the cavity. Microhybrid or microfilled composites are then used as the final layer

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Composite Restoration for diastema closure

Midline Diastema

After composite

Placement of composites in cervical defects Cervical defects are caused due to caries, abrasion, erosion or abfraction and a combination thereof. Although management of these defects involves similar procedures, their proximity to the gingiva makes it difficult to restore. Before any preparation, a gingival cord is placed in the sulcus to allow a proper access to the defect and to keep away sulcular fluid or blood from the cavity margins. EFE of the cavity depends on whether the base of the defect is in the cementum or in the dentin. Wherever the cavosurface margins can be placed in the enamel, a bevel is recommended. Since bond strengths with the cementum are weak, no additional bevel is recommended at the cervical region in cases where the base is in the cementum. This prevents any excess removal of the surrounding dentin.

A round bur is used to roughen the surface of the cavity and a long bevel is placed on the occlusal edge of the cavity. This gives an additional retention especially in cases of smooth, shiny, sclerotic dentin. After etching, the cord is changed and bonding adhesive is applied followed by a flowable composite which is used as an intermediate layer. A hybrid or microhybrid composite is then placed in the extension of the cavity. The gingival cord is removed after completion of the filling to facilitate finishing and polishing. The occlusion is adjusted, especially eccentric contacts, to take care of primary or secondary abfractions. Fine diamonds or carbides are used to finish the margins. A silicone disc is used to finish the res-

93

toration following various planes. The restoration gets its final luster from the polishing paste.

Composite Restoration for cervical abrasion (canine)

Before

After composite

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COMPOSITE BONDING Bonding, which offers a quick and easy way to mask many stains and discolorations, is often an excellent treatment alternative for patients who are not good candidates for bleaching.

Advantages: 1.

Painless.

2.

Little or no tooth reduction.

3.

Generally no anesthetic required.

4.

Less expensive than porcelain laminates, crowning or capping.

5.

Avoids potential pulp or gum irritation that may occur when reducing tooth for full crown.

Disadvantages: 1.

Can chip or stain.

2.

If orthodontic treatment is required, it should be completed before bonding.

3.

If orthodontic retainers are worn, holding wires should be Teflon-coated (stainless steel can cause discolorations with some types of bonding materials).

4.

Extreme care must be taken to avoid metals (such as hair pins) from coming into contact with bonding.

5.

Bonding has a limited esthetic life expectancy.

6.

Certain types of stains (especially dark ones) cannot be covered well with bonding.

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7.

May involve minor tooth reduction to remove some of the stains.

8.

Unless margins are finished perfectly, gum irritation can occur.

Bonding can be of two types: A. Direct.

B. Indirect.

A. DIRECT COMPOSITE VENEERS: Indications: • White spot lesions.

• Severe fluorosis discoloration.

• Severe hypoplastic discoloration.

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Procedure: Before isolation of the field, a tapering bullet-nosed diamond instrument is used to â&#x20AC;&#x153;rough outâ&#x20AC;? labial chamfer-shoulder preparations. The chamfer preparation should extend gingivally to just level with the crest of the gingival tissue, proximally to just labial to the mesial and distal contact areas, and incisally to the crest of the incisal ridge.

Isolation of the field : Proper isolation of the field is accomplished by placement of a rubber dam and a properly stabilized No. 212 gingival retraction clamp (Ivory 212 S.A.).

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Preparation: The chamfer-shoulder preparation is then completed on the labial enamel surfaces using a bullet-nosed diamond instrument. Three important reference points serve as guidelines for the labial veneer chamfer-shoulder margins, namely, the free gingival crest, the proximal contact areas, and the incisal ridge. The gingival margin of the preparation should extend cervically to just short of the free gingival margin of the preparation should extend cervically to just short of the free gingival margin. The mesioproximal and distoproximal borders of the preparation end just slightly labial to the contact areas to allow convenient access for finishing purposes. Incisally, the preparation extends to the crest of the incisal edge, usually without palatal overlap.

To provide adequate labial thickness of the composite material, optimal depth in the preparation is required. The preparation should extend as deep as possible into the labial enamel thickness without exposing dentin.

Matrix. A careful matricing technique simplifies the finishing of the composite material and enhances the final result. The labial half of a thin crown form is cut and subsequently trimmed to extend approximately 0.5 mm beyond the gingivoproximal margins of the preparation. Accurate embrasure fitting of the crown form matrix to ensure restoration of the exact labial contour desired without requiring extensive labial finishing should be the primary goal of the matrix fabrication technique.

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Acid etching. Many light-cured composite materials come with gel-type etchants.

An etching gel is painted over the enamel surface area and left in place for a minimum of 15 to 20 seconds; continuous stroking motion is not used. After 12 to 15 seconds of thorough water lavage, the labial enamel is thoroughly air dried.

Bonding. A new-generation enamel dentin bond resin should be carefully applied to the enamel surface. A small ball of bond resin is applied to the midenamel region on the end of a soft fine-tipped brush. Then it is thinly spread peripherally toward the enamel cavosurface periphery and gently blown with air.

The composite material may be placed over the bond resin surface before lightcuring or preferably after the bond resin has been cured by means of a 20-second 99

exposure to visible light. The latter procedure is recommended since the composite material is much easier to control when placed on a prepolymerized surface. After the 20-second period of light cure, the air-inhibited layer is clearly evident.

Insertion. A polyethylene strip is placed between the proximal chamfer margins and the adjacent teeth to control the placement of the composite material. By means of a flat-bladed anodized aluminum-coated instrument, the composite paste is then applied and contoured over the labial surface. Wetting the side of the instrument with a little bond resin before contouring facilitates the procedure and allows for proper shaping and forming of the composite material without "pull back". The prefitted crown form matrix is filled with additional composite material and subsequently placed in proper alignment over the labial surface. Ideally, the composite material should be highly viscous, readily moldable, and free of "slumping" or uncontrolled flow. The flat-bladed composite instrument wetted with a slight amount of bond resin may be used to shape and form the marginal areas before curing, in which case it is unnecessary to remove gross excess during finishing or the excess composite may be allowed to squeeze between the matrix and the chamfer margins.

Proper placement of polyethylene strip for isolation

Bulk pack placement of composite material over labial surface.

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Shaping composite with Teflon instrument wetted

Composite filled crown form matrix initially

with bond resin prevents â&#x20AC;&#x153;pull backâ&#x20AC;?.

adapts to labial surface.

The composite material is then cured by means of a 40-second application of visible light from both labial and lingual directions, preferably using a light tip with an end diameter of 12 to 15 mm. After cure, the proximogingival excess composite material is "flaked" away using an explorer. The crown form matrix is then "peeled off" the composite surface from which it separates cleanly.

When the matrix crown form is removed, a smooth, highly reflective matrix-cured surface should be observed, and if the matricing and insertion techniques have been performed satisfactorily, only a small amount of composite marginal excess is observed.

Precuring of the composite material by means of a 5-second application of visible light.

Proximogingival gross excess composite material flaked away with explorer, followed by 40 second final light cure.

Labial composite veneer after final cure.

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The matrix form is peeled away from the composite material

The matrix cured labial surface before finishing

Finish. In finishing, most of the smooth matrix-cured labial surface should be left intact if possible. Marginal finishing should be done by means of a tapering, multifluted finishing bur, and final finishing is carried out with aluminum oxide discs. The use of 3/8-inch aluminum oxide discs on a small-headed snap-on mandrel facilitates the finishing procedure in the gingival region. Careful adjustment of the occlusion in centric, protrusive, and protrusive lateral positions should follow. Group function is mandatory.

Marginal excess composite material is removed using a tapering carbide bur.

The fine tapering tip of the carbide bur allows easy access into difficult to reach areas.

Three eighths-inch aluminum oxide discs

Finished labial veneer restoration.

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complete contouring and surfacing.

Although direct labial veneer composite restorations are mainly indicated for white spots, severe fluorosis, and severe hypoplastic discoloration, it should be remembered that indirect porcelain veneers may also be utilized.

B. INDIRECT COMPOSITE VENEERS: Abrasion considerations: Many composite resins wear much like natural tooth structure and do not cause iatrogenic wear of the opposing dentition.

Darkly stained teeth. Indirect composite resin can cover dark color without opaquing agents while retaining a vital appearance. â&#x20AC;˘ Conservation of tooth structure. Tooth preparation for composite resin laminate veneers can be more conservative than that for porcelain alternatives because composite resin does not require 0.5 mm thickness, as does porcelain. Composite resin can be much thinner in spots and still function well. â&#x20AC;˘

Fabrication alternatives. Indirect composite resin laminate veneers can be

fabricated either in the office or in the dental laboratory. They can be light cured or processed. They can be made of micro-filled, small particle, or hybrid composite resin. The glass in the small particle or hybrid composite resin can be etched with hydrofluoric acid, which provides micromechanical retention rivaling that of etched porcelain. â&#x20AC;˘ Chairside repairs. These restorations can be repaired at the chairside with lightcured composite resins. The technique described below is for a light-cured hybrid composite resin that is heat tempered, etched with 10% hydrofluoric acid gel, and treated with silane. The silane chemically bonds to the remaining glass

103

particles and then to the luting composite resin, which is used to attach the veneer to the etched enamel surface of the tooth.

Procedure 1. Clean the tooth and the neighboring teeth with pumice.

2. Select the desired shades of composite resin while the teeth are wet with saliva.

3. Determine the desired alignment of the teeth.

4.

Prepare the eight maxillary anterior teeth by removing small amounts of

enamel with a medium grit flame or chamfer diamond bur. If only minimum preparation is necessary to improve alignment and increase facial contour, remove only 0.25 to 0.50 mm of enamel from the facial area and none from the incisal area. If incisal reduction is necessary, remove 1 to 1.5 mm.

Anterior preparation without incisal reduction

Anterior preparation with incisal reduction

5. Make a full arch impression of the prepared teeth with a vinyl polysiloxane impression material. No retraction cord is needed because the margins are placed at the gingival crest.

6. Make a full arch irreversible hydrocolloid opposing impression.

7. Place a provisional restoration if needed

104

8. Pour stone models of both the prepared and the opposing arches. Veneers can be fabricated on the stone model by using a separating medium or on a flexible model as described below.

9. After the stone is fully set, soak the model of the prepared arch in water for 10 minutes and make an irreversible hydrocolloid impression of the model.

10. Inject a vinyl polysiloxane impression material (medium to heavy viscosity) into the irreversible hydrocolloid impression and form a flexible model. This technique was first developed by Dr. K. Michael Rhyne for use in indirect composite resin inlay fabrication.

Vinyl polysiloxane is injected into an alginate impression of a stone model of prepared teeth.

11. On the flexible model, fabricate composite resin veneers using a technique similar to that described for direct intraoral application.

Composite resin is applied to the flexible.

12. Remove the veneers from the flexible model.

105

13. Contour and polish the veneers using 12- and 30-fluted finishing carbide burs in a high-speed hand-piece or porcelain contouring and polishing wheels on a lathe.

14. Place the veneers on the original stone model to check the fit and margins; adjust further if necessary.

Eight indirect composite resin veneers on a stone model.

15. Heat treat the veneers in boiling water or a heat device, such as the Coltene unit, for 10 minutes to achieve the heat-curing benefits.

16. Acid etch the lingual side of the veneers with 10% hydrofluoric acid gel for 30 seconds or lightly sandblast with a microetcher or air abrasion unit and rinse thoroughly.

Hydrofluoric acid gel (10%) is applied for 30 seconds.

17. Evaluate the internal surfaces of the veneers to ensure that an etched surface has been achieved

106

Etched internal surface of the hybrid composite resin veneer.

18. Clean the teeth with No. 4 fine pumice in a prophylaxis cup, rinse, and dry with water-free and oil-free air.

19. Use 37% phosphoric acid for 15 seconds to etch the enamel and remove the smear layer from any exposed dentin surface of the first central incisor.

Enamel surface is etched with 37% phosphoric acid.

20. Rinse thoroughly.

21. Leave the tooth surface slightly moist for wet bonding.

22. Using a brush, apply silane coupling agent to the internal surface of the veneers and air dry.

23. Liberally coat the etched surfaces with a hydrophilic primer from a fourth generation dentin and enamel bonding agent and dry the primer with oil-free and water-free air until the surface appears glossy without being wet. This indicates that the "hybrid" layer has been established in the dentin and the enamel is thoroughly coated with the resin in the primer.

107

Bonding resin is applied to the etched enamel.

24. Paint a thin layer of bonding resin onto the internal surface of the veneers.

25. Apply a luting composite resin to the internal surface of one of the veneers.

Place the veneer on the prepared tooth and remove excess luting composite resin with a brush dipped in bonding agent

.

Excess luting composite resin is removed with a brush dipped in bonding agent.

26. Light cure for 40 seconds on the facial and lingual surfaces of the tooth.

Luting composite resin is light cured.

27. Remove excess cured luting composite resin with a #12 surgical blade or a sealer.

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Excess cured luting composite resin is removed with a # 12 surgical blade.

28. Place the other veneers in the same fashion.

29.

Finish the margins with 12- and 30-fluted carbide finishing burs, fine

diamonds, rubber polishing cups, finishing disks, or other composite resin finishing techniques.

Final anterior restoration with various layers displayed.

Preoperative view of tetracycline-stained teeth.

109

Postoperative view of eight indirect composite resin veneers.

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COMPOSITE INLAY Posterior composite materials have been available to the dental profession for over three decades.

Although posterior composite restorations have increased in popularity, direct composite restorations are still considered to have a number of limitations.

1. Despite the incremental build up technique, polymerization shrinkage of the resin during curing is still considered to be a problem which contributes to marginal defects, cuspal distortion, crack formation, and propagation within the tissues of the tooth and resultant postoperative sensitivity.

2. Lack of stability in anatomic form and susceptibility to damage in load bearing situations.

3. Water sorption with resultant hydrolytic instability.

4. Technique sensitive and user demanding in terms of manipulation and time.

Composite inlay is one candidate system which overcomes the above limitations.

Definition: â&#x20AC;&#x153;A composite inlay is a restoration which is cemented into a dental cavity as a solid mass that has been fabricated from the composite resin with a form established either by an indirect or a direct procedure.â&#x20AC;?

Thus inlay fabrication techniques include direct, direct/indirect, and indirect techniques.

111

INDICATIONS & CONTRAINDICATIONS Indications: 1. Require tooth colored restoration in a posterior tooth.

2. Patient with a good standard of oral hygiene.

3. Cavity free from marked undercuts.

4. Sufficient tooth substance available for bonding 5. Teeth in which strengthening/ protection of remaining structure is indicated.

7. No evidence of excessive tooth wear in relation to the patientâ&#x20AC;&#x2122;s age.

8.

Patients with actual/ perceived needs warranting the use of alternative

materials.

9. Ideally, where all the cavity margins are in enamel.

Contraindications: 1. Patients with poor oral hygiene/ inadequate motivation.

2. Teeth exhibiting gross wear.

3. Teeth with insufficient tooth substance for bonding.

4. Preparations with excessive undercuts.

5. Where adequate moisture control cannot be achieved.

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Classification of composite inlays: Composite inlays can be classified according to the method of construction, method of curing, and type of composite.

Method of construction: Composite inlays may be constructed by direct or indirect methods.

Direct technique: Inlays are constructed in the prepared cavity in the mouth, prior to removal for additional curing, finishing and polishing.

Indirect technique: Inlays may be chair side fabricated or laboratory fabricated.

113

Method of curing: Composite inlays may be supercured, secondary cured or merely cured by a conventional VLC( visible light cure) unit at ambient temperatures.

1. Super cured: This may be described as a one-stage cure at elevated temperature under pressure, the composite employed being heat cured rather than light cured as used in the secondary and conventional cured systems. Eg for it is the SR- Isosit system, where the inlays are cured at 120째C at 6 bar pressure under water.

2. Secondary cured: After initial light curing at room or body temperature, additional curing is affected by heat and light. Eg for this type of system are the Coltene Brilliant esthetic Line system, in which the inlay is secondary cured in high intensity light at up to 120 0 for seven minutes, and the Kulzer inlay system, in which the inlay is secondary cured in high intensity light in an enclosed light activating unit attachment with internal mirrored surfaces( vide infra) 3. Conventional cure One mode of curing only is employed in such systems. An example is the EOS system, where the inlay is cured by light only, on a die. Conventional cured inlays may be secondary cured.

III. Type of composite: Composite inlays are generally made from the existing categories of dental composite types, as classified according to the filler types, for example:

114

1. Microfilled composite, Eg SR- Isosit; 2. Fine hybrid composite, Eg Coltene Brilliant; 3. Coarse hybrid composite, Eg Kulzer inlay.

Indirect composite inlay systems: At present atleast four indirect composite systems are available: SR- Isosit system This system was first reported in 1983 in dental literature, but was made commercially available only in 1986.

The inlays after shaping on a die, are subjected to heat and pressure polymerization, a temperature of 120 0 and 6 bar pressure being used for ten minutes in the system specific processing unit( the Ivomat).

Composition: Homogenously filled composite material containing 55% radioluscent colloidal silica 20% radioopaque lanthanum fluorides.

Available in seven non Vita shades with six mix- in colors.

Coltene Brilliant The Brilliant esthetic Line inlay/ onlay system was first introduced in Switzerland in 1986 October.

115

Composition: The system incorporates a fine particle size (0.5 micro meters) hybrid composite containing 78.5% by mass glass filler and is available in four Vita shades and has seven paint on colors.

The inlays are built up and light cured in increments on a laboratory fabricated die, prior to further polymerization in the Coltene DI-500 light/heat curing oven for 7 minutes at a temperature rising to 120 0. This restorative system can be deployed in both direct as well as indirect modes, as well as being used as a direct placement restorative. Before cementation, the composite restoration is subjected to a photothermic treatment (post curing process) in a special oven. This procedure allows the optimal resin conversion rate to be reached in few minutes ensuring dimensional stability. This effect is of paramount importance as photocured resins are known to continue their polymerization spontaneously which subsequently generate internal and marginal stresses.

Kulzer inlay: Employed is the Estilux Posterior CVS composite, a glass ceramic filled material containing 80% filler by mass and available in four shades, with a more heavily filled (86% by mass) radioopaque base component.

Direct inlays are produced intra- orally and indirect inlays on a die by conventional light curing prior to tempering for either 180 s in the Dentacolor XS light unit, or 6 min in the light box, an accessory to the Translux EC intraoral light unit.

Visio- Gem Was introduced in 1983 as a material suitable for the construction of anterior composite veneers, but its use was expanded in 1985 to include indirect inlays. In

116

this system, the inlays are initially cured in the ESPE Visio Alfa light source, followed by a fifteen min light cure under vacuum in Visio Beta unit Clinical technique for adhesive inlays  Despite the differences in the physical properties of composite and ceramic inlay materials, the suggested cavity preparation designs may be similar.

The concepts described above for adhesive preparations may be employed.

This type of restoration will normally be appropriate to larger rather than smaller cavities, and will often be a replacement for a failed amalgam or gold restoration. While cavity designs for direct placement posterior composite restorations may involve only minimal preparation other than that required for caries removal, preparation for inlays, of necessity involves preparation of the cavity to create withdrawal form.  The aesthetic inlay cavity will therefore often have an approximal ‘box’ and occlusal key.

Dimensions of the preparation: A typical inlay cavity in premolars may have an interproximal box width equal to one half of the buccolingual width and an occlusal isthmus width of one third the BLW. For molars, the typical inlay cavity has a box width of 0.4 BLW , with an isthmus width of 0.29 BLW. Cavities should be at least 2 mm deep occlusally.  The taper for the preparation should be greater than that employed for gold inlay preparations, i.e. at least 6°, given that the inlays are weak before

117

cementation and try-in or removal from a near parallel preparation may result in fracture of the inlay. ď&#x192;&#x2DC; No bevels should be placed on the occlusal aspect of the cavity, as thin sections of composite or ceramic may be prone to fracture under occlusal loading. ď&#x192;&#x2DC; The composite inlays should have rounded internal line angles unlike the sharp or atleast well defined line angles widely advocated for gold inlay cavities. Such a preparation would be considered unnecessary for bonded composites and considered wasteful of tooth substance.

ď&#x192;&#x2DC; All cavity margins should be in enamel and they should be supragingival to permit moisture control during placement of the inlay.

All line angles should be rounded Consequently from the existing knowledge and understanding of indirect composite inlays and onlays, it has been suggested that the following principles should apply to the tooth preparation.

118

1.

Adopt as conservative an approach as is commensurate with appropriate preparation for an indirect restoration, limiting withdrawal form to enamel.

2.

Create preparations in which the restoration will have optimum occlusal protection and margin angles.

3.

Aim to restore the strength of the tooth. Clinical and laboratory technique for aesthetic inlays are outlined in Table. Using these techniques, a satisfactory aesthetic result is achieved.

Clinical and laboratory techniques for aesthetic inlays Operation Stage 1 Impression technique Laboratory instructions

Rationale Request for etching of the fitting surface of ceramic inlays with hydrofluoric acid to provide a micromechanirally retentive fitting surface The fitting surface of composite inlays are sandblasted as the achievement of a micromechanically retentive fitting surface A silane bond enhancer should be applied to both ceramic and composite inlays both in the laboratory and also pnor to cementation

Temporary restoration

The temporary restoration should be constructed in a light or chemically cured provisional material and cemented with a eugenol-free temporary luting material.

Stage 2 Remove temporary and dean cavity with pumice

Removes contaminants such as eugenol

Handle inlay with care, try into Inlay is weak prior to cementation cavity: do NOT check occlusion If satisfactory fit, clean inlay Fitting surface may have been contaminated with fitting surface with phosphoric salivary pellicle acid for 15 seconds Apply silane bond enhancer to Silane will improve adhesion of resin to ceramic inlay by 119

inlay fitting

Circa 20% surface and allow to evaporate

Isolate, preferably under rubber dam

Saliva and/or blood contamination will reduce bond strength

Apply matrix, or organise Excess luting material will cause gingival irritation alternative means for removal of excess luting material at gingival margin, such as floss and Superfloss.

Mix luting material and apply Application of luting material to inlay may result in to cavity fracture of inlay Place inlay slowly and carefully

Rapid insertion of the inlay may result in its fracture

Remove excess luting material Removal of excess luting material is much more difficult from accessible surfaces with when it has been cured sponge pellets OT equivalent, and interproximal excess with a probe or floss if a matrix has not been placed air-inhibition gel

This will allow full polymerisation of the lute and prevent removal of the uppermost layer when finishing margins

Light cure from all directions in excess of manufacturer's suggested timing inlay.

It is not possible to overcure a composite and light is absorbed by the especially if a dark shade has been chosen Physical properties of dual-cure materials are better when light-cured

Finish margins, check occlusion in all positions

Smooth margins will not retain plaque and polish

Composite onlay preparations: With regard to onlay preparations, the cusps to be covered, in particular the functional cusps, should, in opinion of authors, be reduced by 1.5 mm to 2 mm.

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The preparation of a groove in the dentine exposed by reducing cusps or the incorporation of pin channel in the preparation may be desirable to limit and to counter the substantial shear forces along the composite/ tooth interface during heavy occlusal loading, in particular during lateral excursions.

Advantages of indirect composites: 1.

Control of polymerization shrinkage.

2.

Enhanced physical properties.

3.

Correct restoration contour is more readily achieved.

4.

Improved control over marginal adaptation.

Depending on the restorative material to be used, minimal thickness and width are required for occlusal isthmus and cuspal coverages.

The semi direct intra oral technique (Indirect direct) requires more taper greater than 15 deg to facilitate removal of the restoration from the cavity. The indirect technique (semi direct extra oral) can tolerate small internal undercuts which can be later compensated with a die spacer.

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ESTHETICS WITH CERAMIC METAL CERAMIC AND ALL-CERAMIC RESTORATIONS Most fixed prosthodontic treatment involves the replacement and restoration of missing teeth by artificial substitutes that are not readily removable from the mouth. Its focus is to restore function, esthetics and comfort. These restorations can offer exceptional satisfaction for both patient and dentist. It can transform an unhealthy dentition with poor function into a comfortable, healthy occlusion capable of years of further service while greatly enhancing esthetics. Treatment can range from fairly straightforward restoration of a single tooth with a cast crown , replacement of one or more missing teeth with a fixed partial denture, to a highly complex restoration involving all the teeth in an entire arch or dentition.

In many dental practices the ceramic crowns and bridges are one of the most widely used fixed restorations. This has resulted part from technologic improvements in the fabrication of restoration by dental laboratories and in part from the growing amount of cosmetic demands that challenge dentists today.

Metal ceramic and all-ceramic restorations have excellent esthetic potential. The metal ceramic restorations owe their popularity to the simplicity of bridge construction, durability, strength, marginal adaptation and versatility of use. They are less technique sensitive as compared to the all-ceramic restorations and can be used successfully for various complex clinical situations like long span bridges, full-mouth rehabilitation as also a number of semi-fixed types of appliances. Although esthetics in metal-free ceramic restorations is unmatched, the esthetics achieved with metal ceramics is also good and the trial can be done at every stage of fabrication, thus reducing the possibility of repeats.

All-ceramic restorations are characterized with a dentin like core which makes it possible to mimic the translucency of natural teeth. They are bio-compatible with the gingival tissues and exhibit excellent marginal fit due to newer thermoplastic processing while some exhibit wear resistance similar to that of enamel. All-ceramic restorations are indicated for crowns, veneers, inlays, onlays and three unit bridges with the premolar as the distal-most abutment. AIIceramic restorations can be even bonded to teeth giving 122

additional retention. A good laboratory support is essential to fabricate allceramic crowns.

A preoperative analysis is vital for case selection and designing the preparations The dentist has to correctly execute the tooth preparation as any faulty preparation can result in over-contouring or under-contouring or reduce resistance and retention of the restorations.

Preoperative analysis A preoperative analysis of the teeth to be prepared should be made much before the day of the preparation. A preoperative model would help in determining the length, the labiolingual thickness, the convexity and taper of the tooth. The position of the cingulum and the occlusion will help to determine the extent of the preparation. X-rays would help in determining the pulpal morphology and crown-root ratios. A thick tooth with less convexity and taper, with a retracted pulp, large horizontal overlap and shallow vertical overlap, will present little difficulty during tooth preparation Determining the incisal edge position in the preparation is of crucial importance to create an esthetic restoration. The incisal edge also is significant to give the restoration the required retention. The dentist should use a reference when preparing the incisal aspect.

Tooth serves as its own incisal reference for the incisal edge position of the preparation and The adjacent tooth serves as the reference for incisal and facial reduction of the preparation.

Silicone index A silicone index is made to record the horizontal overlap and the inclination of the teeth to be prepared and, the preparation can be gauged by reinserting the silicone index.

Indications of metal ceramic crowns 1. Teeth requiring complete coverage with high demand for esthetics 2. Retainer for a fixed partial denture 3. Situations where rests and guide planes must be incorporated in the restoration

123

4. Extensively destroyed teeth as a result of caries, trauma, or existing previous restorations with a need fro superior retention and strength 5. Need to recontour axial surfaces or correct minor malinclinations 6. In certain situations correction of the occlusal plane.

Contraindications 1. Patients with active caries or untreated periodontal disease 2. Young patients with large pulp chambers 3. When an intact buccal wall is present 4. when the use of a more conservative retainer is possible Advantages 1. Combines the strength of an all metal crown with the esthetics of an all ceramic crown.

2. Excellent retentive qualities as all axial walls are included 3. Easy correction of axial forms Disadvantages 1.

Removal of substantial tooth structure

2.

Subject to fracture because porcelain is brittle

3.

Difficult to obtain accurate occlusion in glazed porcelain

4.

Shade selection can be difficult

5.

Inferior esthetics compared to all ceramic

6.

Expensive

Preparation sequence for anterior metal ceramic crown The preparation is divided into five major steps: 1.

Depth guiding grooves,

2. incisal or .occlusal reduction, 124

3. labial or bucca1 reduction in the area to be veneered with porcelain, 4. axial reduction of the proximal and lingual surfaces, 5. and final finishing of all prepared surfaces.

Depth Preparation grooves- three depth grooves are placed one in the centre of the facial surface and one each in the approximate location in the mesiofacial and distofacial line angles. These will be in two planes: the cervical portion to parallel the long axis of the tooth, the incisal portion to follow the normal facial contour. The grooves usually should be 1.3mm deep approximately.

The incisal grooves usually extend halfway down the facial surface, although (depending on the shape of the tooth) they may extend to include the incisal two thirds.

On small teeth it may be advisable, to keep the cervical grooves somewhat shallower near the margin.

Three depth grooves are placed (about 1.8 deep) in the incisal edge of the tooth.

This will provide the needed reduction of 2 mm and allow finishing. The depth of these grooves is verified with a periodontal probe. When initially positioning the diamond, it may be helpful to observe the long axis, of the opposing tooth in the intercuspal position and to orient the instrument Perpendicular to that. The grooves must not be too deep; otherwise, an overreduced and undulating surface will result.

Incisal Reduction: The completed reduction of the incisal edge on an anterior should allow 2 mm for adequate material thickness to permit translucency in the completed restoration.

Caution must be used, however, because .excessive occlusal reduction shortens the axial walls and thus is a common cause of inadequate retention and resistance form in the completed preparation. This can be particularly problematic on anterior teeth where as a consequence of tooth form, most of the retention is derived from the proximal walls.

The islands on the remaining tooth structure must be removed.

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STEPS IN PREPARATION OF METAL CERAMIC CROWNS

Depth orientation grooves

Incisal Reduction

Two plane reduction- incisal two-thirds Completed labial reduction

Proximal reduction

Lingual reduction

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Finishing â&#x20AC;&#x201C; Chamfer finish line

Clinical situation

Completed metal ceramic crowns

Preparation of abutments for metal ceramic bridge

Lingual view of the same

Intra oral view

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Labial Reduction: a minimum of 1.2 mm is necessary for to permit the ceramist to produce a satisfactory appearance, although 1.5mm reduction is preferred. Reduction of the incisal portion of the labial surface is done and all tooth structure is planed of to the depth of the orienting grooves. The gingival portion of the labial surface is likewise reduced to the depth of the grooves creating a shoulder at the cervical aspect. The reduction is carried around the labioproximal line angles to a point 1mm lingual to the proximal contacts. Although the wings of tooth structure can provide resistance to rotation, that is not the primary reason for their existence. They help to conserve tooth structure.

Lingual and proximal reduction: the lingual surface is reduced with a small wheel diamond to obtain a minimum of 0.7mm of clearance with the opposing teeth. Those portions of the lingual surface that will have a ceramic veneer should have 1.0mm clearance. The junction of the cingulum and lingual wall must not be overreduced as it will affect retention.

Much of the proximal reduction would have been accomplished during the preparation of the labial cervical margin, however, the lingual and the proximal walls are reduced to produce a chamfer finish line .

Final Finishing: a radial fissure bur is used for the finishing of the labial surface. All angles and edges are rounded with the sides of the bur while the end of the bur is forming the radial shoulder finish line.

The finish lie advocated for PFM preparations are usually a shoulder or a shoulder with a narrow bevel. Some investigators have reported that metal ceramic crowns with metal gingivofacial margins made over shoulder finish lines distort less during porcelain firing. A possible explanation fro this would be that a shoulder provides space for an internal rib of metal to buttress the margin. However, there is a compelling reason to not use a metal margin at all, the metal collar that accompanies a bevel on a shoulder often requires the finish line to be placed deep in the gingival sulcus to hide the metal. If some form of shoulder without a bevel is used , an all ceramic margin can be fabricated . this eliminates the metal at the faciogingival margin af the finished preparation and there is no 128

need to bury the margin beneath the gingiva. The finish line is smoothed with hand instruments , this will help in removing any lip of enamel that might extend occlusally from the cavosurface angle.

Esthetic considerations for Metal Ceramic Restorations The poor appearance of some metal ceramic restorations is often due to insufficient porcelain thickness. On the other hand, adequate porcelain thickness is sometimes obtained at the expense of proper axial contour (such overcontoured restorations almost invariably lead to periodontal disease). In addition, the labial margin of a metal ceramic crown is not always accurately placed. To correct all these deficiencies, certain principles are recommended during tooth preparation and fabrication of the metal ceramic prosthesis. Otherwise good appearance is only achieved at the expense of the periodontium.

Subgingival margins may be indicated for esthetic reasons, particularly when the patient has a high lip line and the use of a metal collar labial margin is contemplated.

However, if the root surface is not discolored, appearance can be restored with a supragingival porcelain labial margin sometimes called a collarless design.

Metal collars when used may be hidden below the gingival crest, although they may cause some discolouration if the gingiva is thin. Successful margin placement within the gingival sulcus requires care to ensure that inflammation and /or recession, with resulting metal exposure, are avoided or minimized.

The preparation sequence listed above must be followed and adequate amount of preparation must be made to ensure optimal esthetics.

Proper framework design for metal ceramic prostheses (especially multiple unit and long span fixed partial dentures) must be planned. The framework design controls the morphology of the restorations and in turn promotes good health. Good physiology and good esthetics promote health.

There are three areas of framework design that promote proper construction of fixed prostheses and will ensure good oral health of the hard and soft tissues: marginal fit, contour control, and lingual metal band design. These are the factors that determine

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structural integrity, esthetic appearance, and the physiologic response to the fixed partial denture or individual crown.

Marginal fit The accuracy of the marginal fit has a significant influence on maintaining the health of the hard and soft tissues. There are three types of inaccuracies pertaining to marginal fit: short margin, overexpansion, and underexpansion. A well-fitting crown placed on an abutment protects the dentinal hard tissues by sealing the prepared tooth from the bacterial environment of the oral cavity. The short margin, whether caused by a discrepancy between the preparation and the impression or an error in the fabrication of the restoration, is an open invitation to plaque attachment leading to inflammation.

Overexpansion Overexpansion can cause the cast restoration to rock on the prepared tooth, opening either the facial or lingual margin, but, even more detrimental, if seated, the overexpanded restoration creates an overhang extending beyond the margin of the tooth.

The overhang creates an area for plaque collection. The shelf created by the overexpansion of the casting prevents debris from being easily removed by the patient.

The persistence of this condition will lead to deterioration in the health of the surrounding tissues.

Underexpansion Underexpansion makes fitting of the cast restoration extremely difficult because the internal dimension of the casting is smaller than the preparation. Machining the internal surface of the casting, ie, making its internal dimension larger, may allow the casting to seat fully on the prepared tooth, but it will not eliminate the physiologic negative of a short margin. The marginal periphery of an underexpanded cast crown is always smaller (less in circumference) than the marginal periphery of the prepared tooth.

Placing an underexpanded or overexpanded crown, which has been machined to fit, will always leave an exposed surface around the periphery of the prepared tooth.

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Control of marginal fit The accuracy of the fit of a crown casting can be controlled by tooth preparation, complete and accurate impressions, accurate cast pouring, use of controlled thickness cement spacers, fabrication of accurate wax patterns, and the control of investment mold expansion.

Contour control Fabricating a ceramic metal restoration is a tremendously detailed procedure that requires knowledge of structural mechanics, metallurgy, chemistry, biology, colorimetry, and esthetics. A good technician must not only possess working knowledge and experience in these areas but also must have great manual and perceptual skills. If the technician does not have this knowledge or skill, it is doubtful that the patient is going to receive a dental restoration that promotes good health and a pleasant appearance.

In fabricating the ceramic metal restoration, the technician must have a clear understanding of how the restoration will look when completed, how it is going to achieve the esthetic concerns of the patient, and how it is going to behave structurally to withstand the forces of the oral environment. The restoration must be strong yet have the natural appearance and good physiologic adaptation to the patient desires. If the framework is too bulky, the porcelain will be well supported, but due to its over contour, the prosthesis may impinge on the tissue. When the framework is over contoured, the thickness of the ceramic veneer must be restricted, preventing it from having adequate thickness to develop the desired color.

A framework that is merely a skeleton may provide more than enough room for the porcelain veneer but it will lack the needed strength to resist a flex distortion, leading to the inevitable fracture of the ceramic.

To achieve optimum esthetics, physiologic adaptation, and adequate strength, the final form must be determined before fabricating the framework. Once a diagnostic wax model has been completed the actual wax pattern for the fixed partial denture framework may be developed by first making an impression of the diagnostic wax-up, then recreating the full form wax-up on the working model and cutting back the completed

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wax sculpture to create a uniform space for the porcelain veneer. Alternatively, the impression of the diagnostic wax sculpture can be used create a matrix for positioning preformed wax patterns.

Interproximal connectors: Design for strength Fixed partial dentures rarely fail because of fracture within a pontic or abutment.

The weak section is the connector area. Inadequate design of the connector can allow the framework to flex. A flex distortion of the framework will result in either a fracture in the porcelain or, in severe cases; the framework itself may fracture at the connector. The size of a connector is determined by the stresses that will be placed upon it. The greater the stress or the longer the unsupported span between the abutments, the greater the requirement for adequate cross section of metal in the connector areas. In the vocabulary of structural engineering, the law of beams states that the strength of beam (its ability to support a load) is proportional to its cross-sectional area.

The cross-sectional area has two factors: height and width. The law of beams also states that the height, in the direction opposing the force, is by far the more important of the two factors. Relating to metal framework design, this law indicates that the strength of a multiple-unit metal framework can be optimized by maximizing the height of the interproximal connector. All the multiple-unit frameworks built in laboratories use the law of beams and their strength is a function of their design rather than bulk. When we translate the structural engineer's vocabulary into the dental laboratory technician's vocabulary, the law of beams means that the occlusogingival connector cross-sectional dimension is of greater importance in providing strength through support to the prosthesis than the faciolingual dimension. This places severe demands on the design and position of the interproximal connector, for it must strongly support the pontic while still allowing adequate space for the overlying porcelain. The faciolingual placement of the connector requires careful planning because the facial aspect of the connector area must allow sufficient space for porcelain placement without sacrificing strength.

To meet the requirements of support and esthetics, the connector is developed in the lingual zone. By placing the connector on the lingual, optimal thickness of porcelain can be placed on the facial aspect in the interproximal. By placing the interproximal

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connector on the lingual surface, maximum strength can be achieved because the connector remains in metal, taking advantage of the greatest occlusogingival connector cross section allowable.

Interproximal design: Esthetics How the interproximal connector is shaped, where it is placed, and how it blends to the pontic body are critical in achieving the optimum esthetics of the restoration. This is a three-dimensional consideration involving the facial form as well as the incisal and gingival aspects. To allow adequate separation of the units without exposing metal, it is essential to provide space for porcelain on both sides of the pontic body. Placing the metal framework toward the lingual allows for the creation of an adequate facial embrasure. Placing the connector toward the lingual will allow for a deep interproximal embrasure creating separation of the units, which is important to the esthetic appearance.

Providing adequate space for porcelain in the interproximal zone will allow the correct thickness of porcelain to be veneered over the framework, ensuring vitality and color the restoration.

Pontic-tissue relationship Porcelain is widely recognized as being compatible with the residual ridge tissues.

Enough space must be provided on the tissue side of the pontic to ensure that the surface will not have concavities and that the porcelain that is in contact with the tissue can be glazed or highly polished, leaving a smooth surface to contact the ridge. Sufficient clearance for porcelain can result in opaque porcelain tissue contact. Opaque cannot be finished to smooth surface by glazing or polishing and will leave rough surface that will collect food and plaque, irritating and inflaming the tissue.

Designing the framework so that the junction of the metal and porcelain occurs on the bottom of the pontic should also be avoided. It is virtually impossible to provide a metal-porcelain junction that is as smooth and as resistant to plaque attachment as an allporcelain tissue contact. When the pontic tissue contact cannot be maintained by the patient, inflammation will occur under the restoration. When constructing the framework wax pattern, it is helpful to place a 1-mmthick wax spacer over the residual ridge area on the working model over which the pontic can be positioned. The wax spacer will hold the 133

wax pontic section in place while creating a uniform 1-mm space under the section. After casting, all the pontics will be a uniform 1 mm from the surface of the tissue. Providing a 1-mm space will permit adequate porcelain thickness to ensure a smooth, properly contoured, and highly glazed surface.

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ALL CERAMIC RESTORATIONS Indications of All Ceramic Crowns 1. High esthetic requirement 2. Considerable proximal caries where the tooth can no longer be restored by composite resin.

3. Incisal edge reasonably intact 4. Endodontically treated teeth with post and cores 5. Favourable distribution of occlusal load.

Contraindications 1.

When superior strength is warranted and metal ceramic crown is more appropriate

2. High caries index 3. Insufficient coronal tooth structure for support 4. Thin teeth faciolingually 5. Unfavourable distribution of occlusal load 6. Bruxism Advantages 1. Esthetically unsurpassed 2. good tissue response even for subgingival margins 3. slightly more conservative of the facial wall than metal ceramic Disadvantages 1. Reduced strength compared to meatl ceramic crowns.

2. Proper preparation extremely critical 3. Among least conservative preparations 4. Brittle nature of material 5. Can be used as single restoration only

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PREPARATION FOR ALL CERAMIC CROWNS

Lingual preparation

Completed preparation

Difference between preparation of All ceramic and Metal ceramic crowns

Clinical Situation

Replacement of old metal ceramic crowns

Completed crowns

Teeth prepared and gingiva retracted

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IPS Empress cores

Etching

Completed IPS Emress crowns

Silane application

Crown cemented in the mouth

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Preparation sequence Complete

ceramic

crowns

should

have

relatively

even

thickness

circumferentially usually about 1 to 1.5mm to create an esthetically pleasing restoration. Only minor differences exist in tooth preparation exist between the metal ceramic and all ceramic preparations, the principle difference being a 1mm uniform shoulder width to provide a flat seat to resist forces directed from the incisal.

Care should be taken to leave the preparation as long as possible to give maximum support to the porcelain. An over shortened preparation will create stress concentrations in the labiogingival area of the crown, which can produce a characteristic â&#x20AC;&#x2DC;half moonâ&#x20AC;&#x2122; fracture in the labiogingival area of the restoration.

Depth orientation grooves : are placed on the labial and incisal surfaces . the grooves are approximately 0.8mm on the labial and 1.5-2mm on the incisal edge.

Three labial grooves are cut with the diamond held parallel to the incisal twothirds, and another set of three grooves parallel to the gingival one thirds. The labial reduction for the all ceramic crown is done in two planes to provide adequate clearance for good esthetics without encroaching on the pulp.

Incisal reduction is done to remove approximately 1.5- 2mm of tooth structure at the incisal edge.

Facial reduction: the tooth structure remaining between the grooves is planed away on the incisal portion of the labial surface. . the gingival portion is reduced with the direction of the bur parallel to the long axis of the tooth. The end of the round tipped tapered diamond is used to form the shoulder finish line. This reduction extends around the labioproximal line angle and fades out on the lingual aspect of the proximal surfaces.

Proximal and Lingual reduction: is done with a small wheel diamond, being careful not to overreduce the junction between the cingulum and the lingual wall. A clearance of about 1mm is achieved to accommodate the mandibular excursive movements and adequate space for the porcelain in the load bearing areas. The shoulder preparation is repeated on the lingual wall parallel to the facial cervical preparation until the lingual shoulder meets the facial shoulder. This margin should follow the free gingival margin and should not extend too far subgingivally.

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Finishing : all axial walls should be smoothed accentuating the shoulder at the same time. All sharp angles should be rounded. The shoulder is smoothed with a sharp round angled chisel to remove any loose enamel rods at the cavosurafec angles.

All Ceramic Systems Aluminous core porcelains: the high strength ceramic core was first introduced by Mclean and Hughes in 1965. they advocated using aluminous porcelain , which is composed of aluminium oxide (alumina) crystals dispersed in a glassy phase. The technique devised by Mclean used an opaque inner core containing 50%by weight alumina for high strength . this core was veneered by a combination of esthetic body and enamel porcelains with 15 and 5% crystalline alumina respectively and matched thermal expansion . The resulting restorations were approximately 40% stronger than those using traditional feldspathic porcelain.

Slip Cast Ceramics: High Strenght core frameworks for all ceramic restorations can be produced with a slip casting procedure such as the in ceram. Slip casting is a traditional technique in the ceramic industry and is used to make sanitary ware. The starting media in slip casting is the slip that is an aqueous suspension of fine alumina particles in waterwith dispersing agents. The slip is applied onto a porous refractory die , which absorbs water from the slip and leads to the condensation of the slip on the die. The piece is then fired at a high temperature (1150 0C). The refractory die shrinks more than the condensed slip, which allows easy separation after firing. The fired porous core is later glass infiltrated, a unique process in which molten glass is drawn into the pores by capillary action at high temperatures. Materials processed by slip casting tend to exhibit lower porosity and producing fewer defects than traditionally sintered ceramic materials. The strength of In –Ceram is about three to four times greater than earlier alumina core materials, a finding that has prompted its use in high stress situations such as FPD’s. Two modified porcelain compositions for the In – Ceram technique have been introduced: In- Ceram Spinell contains a magnesium spinell (MgAl2O4) as the major crystalline phase, which improves the translucency of the final restoration. In ceram Zirconia contains Zirconium oxide (ZrO2) and is said to have the highest strength. Marginal fit of In- Ceram has been reported as very good.

Hot Pressed Ceramics: Leucite Based- hot – Pressed ceramics are becoming increasingly popular in dentistry. The restorations are waxed, invested and pressed in

139

a manner similar to gold casting. Marginal adaptation seems to be better with hot â&#x20AC;&#x201C; pressing than with the high strength alumina core materials. Most hot pressed materials contain leucite as a major crystalline phase, dispersed in a glassy matrix.

The crystal size varies from 3-10 microns and the leucite content varies from about 35-50% by volume depending on the material. Leucite is used as a reinforcing phase due to the tangential stress it creates within the porcelain. Ceramic ingots are pressed at high temperatures from 900-11650C depending on the material into the refractory mold made by the lsot wax technique. The ceramic ingots are available in different shades. Two finish techniques can be used: a characterization technique (surface stain only) and a layering technique, involving the application of a veneering porcelain.

The two techniques lead to comparable mean flexure strength value for the resulting porcelain composite.the thermal expansion coefficient of the core material for the veneering material is usually lower than that of the amterial for the staining technique to be compatible with the thermal expansion coefficient of the veneering porcelain.

Among the currently available leucite- containing materials for hot pressed craemics are IPS Empress, Optimal Pressable Ceramic and two lower fusing materials Finesse and Cerpress.

Lithium Silicate Based: IPS Empress2 is a recently introduce hot pressed ceramic.

The major crystalline phase of the core material is a lithium disilicate. The material is pressed at 9200C and layered with a glass containing some dispersed apatite crystals.

Machined Ceramics The evolution of CAD/CAM systems for the production of machined inlays, onlays, veneers and crowns led to the development of a new generation of ceramics that are machinable.

Cerec System: has been marketed for several years with the improved cerec2 system introduced in the mid 1990s. the equipment consists of a computer integrated imaging and milling system , with restorations designed on the computer screen. At least three materials can be used with this system: Vita Mark II, Dicor MGC, Procad. Vita mark II contains sanidine(KALSi3O8) as a major crystalline phase within a glassy matrix.

Dicor MGC is a mica bsde machinable glass ceramic that contains 70 volume % of crystalline phase. Procad is a leucite containing ceramic designed fro making machined restorations .

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Celay System: uses a copy milling technique to manufacture ceramic inlays or onlays. A resin pattern is fabricated directly on the prepared tooth or on a master die, then the pattern is used to mill a porcelain restoration. As with the cerec system the starting material is a ceramic blank available in different shades . this material is similar to Vita Mark II. Alternatively blanks of Inceram alumina or Inceram Spinell can be used. Marginal accuracy seems to be good.

Procera All Ceram System: involves an industrial CAD/CAM process. The die is mechanically scanned by the technician and the data is tent to a work station where an enlarged die is milled using a computer controlled milling machine. This enlargement is necessary to compensate fro the sintering shrinkage. Aluminium oxide powder is then compacted onto the die and the coping is milled before sintering at a very high temperature (>15500C). the coping is further veneered with an aluminous ceramic with matched thermal expansion. The restorations seem to have good clinical performance and marginal adaptation. They may be suitable for posterior crowns and FPDs , although long term data are needed.

Selection of an All-Ceramic Systems The primary purpose in recommending all ceramic is to achieve the best possible esthetic result. Typically this will be at the risk of reduced longevity due to the potential of fracture of the ceramic and the restoration may have a slightly inferior marginal adaptation than a metal ceramic crown.

Fracture Resistance : most hazards of failure are removed if these restorations are confined to low stress bearing anterior teeth and patients should be carefully evaluated for parafunctional habits. Although newer materials like Empress 2 and In Ceram Zirconia, promise higher strength, the long term data are lacking to determine whether they are satisfactory, particularly for FPDs. Esthetics: a knowledge of the ceramic systems available is a must to select a material that will provide the best esthetics for a patient. This is especially important when matching a single maxillary incisor to an adjacent tooth. The marginal adaptation of a system is very important, even when resin bonding is used. The translucency of the adjacent tooth and discoloration of the tooth must also be considered when selecting the most appropriate system. Highly translucent teeth would not be best restored with a more opaque, high strength core, ceramic system. However, these might be the bets

141

choice if the tooth exhibits discoloration that would not be well masked by a more translucent material. Conversely, when concern exists about fracture, the higher â&#x20AC;&#x201C; strength materials should normally be the first choice.

Abrasiveness: one concern of ceramic restorations is the potential of abrasion of enamel, particularly in patients with parafunctional habits. Whenever possible, a low abrasion material should be considered.

Tissue management A healthy periodontium is a prerequisite for any gingival retraction procedure.

The gingival deflection that takes place should be reversible in nature and should allow vertical and horizontal access to the impression material at the cervical margin.

The retraction should be sufficient to allow a certain bulk of the impression material to avoid tearing or deformation while removing the tray.

The retraction cord is placed in a definite but gentle manner. The thickness of the cord is often determined by the free gingival depth. The cord is placed with a cord packer with continuous strokes in the same direction slowly moving the packer along the margin.

A knitted or braided cord impregnated with an astringent like aluminum chloride or ferrous sulphate is preferred for optimum displacement of gingival tissues.

A double cord technique is used in hemorrhagic cases when a 000 cord or a thin black silk suture is used as the first cord. The second cord used is often a woven or knitted one. After establishing sufficient displacement the second cord is removed.

The retraction cord with the chemical should not be kept for more than 10 min, to prevent irreversible changes in the gingival tissues. Prolonged usage may lead to sloughing of the tissues, inflammation followed by recession, leading to unesthetic results. The impression is then made. The first cord controls-the bleeding allowing clear path for the impression material.

Impression methods Elastomeric impression materials have good accuracy. These materials are technique sensitive and the dentist would take some time and experience to master the technique. The deviation in accuracy varies according to the type and rigidity of the tray, the delay in pouring the impression, the viscosity and the brand variations in

142

products etc.

The tray used can be a perforated metal tray or a custom-made tray. The perforated metal tray is used when putty impression material is used. This is a time saving procedure. Acrylic custom trays are used to make impression in medium and low viscosity impression material. This allows for uniform thickness of 2mm of impression material giving the most accurate impression. Tray adhesive is a must since it prevents separation of the impression material from the tray.

Double mix technique is simple and fast and suitable for a single or few units of crowns. The low viscosity material is injected all over the prepared tooth and the tray loaded with the high viscosity silicone putty is placed over it.

The wash technique is usually used for multiple preparations. It is a double impression technique where the putty impression is taken first. After curing and rinsing of the impression, undercuts and interdental areas from the impressions are trimmed. The shapes of the teeth are also eliminated allowing space for low viscosity material. The second impression is now taken with the injectable silicone. These impressions can be stored for several hours.

Provisionalization of crowns The role of provisional restorations is three fold. It protects the preparation and also helps to establish a corrective interface for the final restoration, both biologically and esthetically. The long term gingival response can be envisaged with provisional restorations and the satisfaction and comfort of the patient can also be gauged. Hence the provisional restoration should mimic the final restoration in form, shape and color.

Many techniques including the use of single preformed polycarbonate crown, shell technique, block technique and heat cured acrylics are used to make provisional restorations.

A polycarbonate crown is used over the prepared tooth. The polycarbonate crown is adjusted for height and axial contours as far as possible. A thin mix of mouth acrylic is placed in the crown which is seated over the lubricated preparation. The excess is then trimmed, the margins are defined. A second relining might be needed to get a superior marginal adaptation.

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In the shell technique which is probably the best and most effective technique, a cast is obtained from the diagnostic wax-up. A polyvinyl template is made on the cast and then the teeth on the cast are under-prepared. Tooth colored acrylic is poured into the template which is placed over the lubricated cast. After curing, the shells are trimmed and finished. The shells are relined in mouth after complete tooth preparation.

Alternatively the provisionals can be made on casts obtained after tooth preparation using the template. This technique provides provisionals with correct contour, contacts, proper occlusion and finish, saving chairside time.

In block technique an acrylic block is molded on the preparation and a free hand sculpting is done by the dentist. This is a time consuming technique hence is not favorable.

The heat cured provisional restorations are long-lasting and serve as better provisionals. They seal the cervical margins, extend till the areas in contact with the periodontium and produce accurate occlusal contact along with good esthetics. A duplicate working cast is obtained and the heat cured provisional is fabricated and then carefully polished with cotton thread wheels, polishing pastes and cemented using non-eugenol cement.

Some dentists make impressions with elastomeric material before tooth preparation. After preparation, mouth acrylic of low viscosity is poured on the impression where the tooth is prepared. The tray is placed in the mouth for a few minutes. A replica of the preoperative tooth form is instantly ready which can be adjusted, relined and finished as a provisional restoration. This technique can be used only when the preoperative tooth form is intact and if esthetic correction in relation to incisal length and incisal profile is not desired.

Try-in All metal castings are evaluated for margin integrity, internal fit stability and adequate space for ceramic material. Intra- occlusal relationship record is needed in extensive rehabilitation cases. Bisque trial for ceramic restorations are assessed for location, site and tightness of proximal contacts, marginal adaptation and favorable centric and eccentric occlusal contact without interferences. Besides the shape, contours and color; adequate surface characterization is checked and incorporated.

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The trial for all-ceramic restorations are assessed for a passive fit margins, proximal contacts, stability, shade, form, characterization and occlusion.

Cementation It is advisable to lute a restoration provisionally to assess the esthetics and function in the mouth for a longer period of time. Noneugenol based cements are preferred. For permanent cementation, sand blasting the inner surface of the metalceramic restoration and the use of a reliable cement with low film thickness is advisable. The luting agent of choice for final cementation of metal ceramic restorations is glass ionomer cement while adhesive resin cements are recommended for all-ceramic crowns. Removal of excess from around the restoration and from the interdental areas should be done with utmost care .

Recall Periodic appraisal of oral hygiene regimen, function and comfort of the restorations should be carried out for successful results. Planned corrective measures have to be initiated at the right time for long service of the restorations.

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LAMINATING Laminating, like bonding, consists of applying a thin veneer of preformed porcelain.

Advantages of Bonded Porcelain Restorations The main advantages of bonded porcelain restorations are the following: 1.

Excellent esthetics. Porcelain offers unsurpassed esthetics and inherent color control. In addition, unlike direct laminate veneers, the porcelain laminate veneers depend less on the esthetic skill of the dentist.

2.

Excellent long-term durability. Porcelain is both abrasion resistant and color stable. In addition, porcelain has excellent resistance to fluid absorption.

3.

Inherent porcelain strength. Porcelain exhibits excellent compressive, tensile, and shear strengths when bonded to enamel.

4.

Marginal integrity. Porcelain restorations bonded to enamel exhibit exceptional marginal integrity.

6.

Soft

tissue

compatibility.

Properly

polished

porcelain is highly biocompatible with gingival tissue.

7.

Minimal

tooth

reduction.

Anterior

porcelain

laminate veneers are considerably more conserving of tooth structure than

porcelain-fused-to-metal

and

all-porcelain

full

coverage

restorations.

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Disadvantages of Bonded Porcelain Restorations The primary disadvantages of bonded porcelain restorations are the following: 1. Time. Multiple visits are required.

2. Cost. Laboratory involvement and additional chair time are required when compared with direct restorations, resulting in higher costs to the patient.

3. Lack of repairability. Porcelain restorations are difficult, if not impossible, to repair.

4. Difficulty in color matching. Although porcelain restorations are color-stable, precise matching of a desired shade tab or an adjacent tooth can be difficult. In addition, shade alteration is impossible after cementation.

5. Irreversibility. Tooth reduction, although often minimal, is required.

6. Inability to trial cement the restoration. Unlike traditional indirect restorations, bonded porcelain restorations cannot be temporarily retained with a provisional cement for evaluation purposes.

INDICATIONS Porcelain laminate veneers may be indicated in areas traditionally restored with single crowns or composite resin veneers for the following: 1. Correcting diastemata 2. Masking discolored or stained teeth 3. Masking enamel defects 4. Correcting malaligned or malformed teeth CONTRAINDICATIONS Porcelain laminate veneers may be contraindicated for the following: 147

1. Patients who exhibit tooth wear as a result of bruxism 2. Short teeth 3. Teeth with insufficient or inadequate enamel for sufficient retention (e.g., severe abrasion) 4. Existing large restorations or endodontically treated teeth with little remaining tooth structure 5. Patients with oral habits causing excessive stress on the restoration (e.g., nail biting, pencil biting) BASIC LABORATORY TECHNIQUE Porcelain-laminate veneers can be fabricated by the laboratory in one of four ways: platinum foil backing, refractory models, direct castings, or CADCAM machining.

Platinum Foil Backing. This method can also be used to construct the allporcelain crown. A very thin layer of platinum foil is placed on the die. The porcelain is layered on the foil. Then the porcelain-foil combination is removed from the die and fired in an oven. Before try-in, the foil is removed and the porcelain is etched.

The use of platinum foil permits the porcelain to be repeatedly removed from and replaced onto the die during restoration fabrication. This permits easier access to the proximal margins. In addition, the thickness of foil creates a space for opaques and tinting agents.

Refractory Models. The use of refractory models is the most commonly used method of porcelain laminate veneer fabrication.

The restoration is fired directly on a refractory die. This eliminates the platinum layer but makes repeated firings difficult once the laminate veneer has been removed from the die.

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The advantages of the refractory model include tighter contacts and the absence of the gap created by the use of platinum foil. The disadvantages are less room for coloring agents and more difficulty in adjusting proximal areas by the technician.

Direct Castings. Cast ceramic restorations are fabricated using the "lost wax" technique. This eliminates the need for multiple firings but requires extrinsic staining for coloration.

CAD/CAM Machining. Ceramic restorations can be manufactured either in the dental office or in the laboratory. A model or video image of the preparation is required, and the restoration always requires modification of the surface porcelain to obtain proper color esthetics.

Clinical Technique 1. Evaluate the high lip line.

2. Administer suitable anesthesia (if necessary).

3. Prepare three horizontal surface depth cuts in the labial surface with a friction grip three-tiered LVS-1 or LVS-2 depth cutting diamond. Depth cuts should be 0.5 to 0.7 mm deep for "ideal" teeth, and 0.3 mm deep for mandibular incisors. Lingually positioned teeth and those with thin enamel require less reduction.

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Three horizontal depth cuts are prepared in the labial surface.

When the three-tiered depth cutting but is held tangentially to the surface of the tooth, only the middle section of the bur penetrates to its entire depth.

4. Prepare three incisal depth cuts with an LVS-3 or LVS-4 diamond bur. (The incisal reduction should create a preparation that is 1 mm shorter than the desired final restoration.)

Three vertical depth cuts are prepared in the incisal edge.

5. Using the depth cut as a guide, prepare the incisolingual finishing line to a modified butt joint with the diamond wheel bur. The labioincisolingual angle should be approximately 75 degrees.

A butt incisal finishing line should slope approximately 75 degrees gingivally from the labial to provide resistance to restoration displacement and to provide for adequate thickness of porcelain at the margin to prevent restoration fracture.

6. Using the depth cuts as a guide, prepare the labial surface with an LVS-3 or LVS-4 diamond bur.

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The labial surface is prepared using the horizontal depth cuts as a guide.

7. Prepare the proximal chamfer finishing lines.

A. For diastema: Prepare a feather-edged finishing line with an LVS-3 or LVS4 diamond bur. The finishing line should terminate as far to the lingual aspect as possible without creating an undercut area, and it should extend from the incisal edge to the point adjacent to the height of the gingival papilla.

The feather-edged finishing line is prepared adjacent to the diastema.

B.

For minimal or no color change and no diastema, see the section on

minimal or no color change in this chapter. i.

Prepare the proximal chamfer finishing line with an LVS-3 or LVS-4

diamond bur to approximately 0.2 mm labial to contact area. ii. Prepare the proximal subcontact area with an LVS-3 or LVS-4 diamond bur.

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If the final porcelain laminate veneer will be similar in color to that of the prepared tooth, the proximal finishing line terminates 0.2mm labial to the contact area.

Proximal representation of porcelain laminate veneer preparation before reduction of the proximal subcontact area. The proximal finishing line terminates 0.2mm labial to the contact area because the final porcelain laminate veneer will be similar in color to that of the prepared tooth. The contact area is indicated with diagonal lines

C. For major color change and no diastema.

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If the final porcelain laminate veneer will significantly differ in color from that of the prepared tooth, the proximal finishing line terminates within the interproximal contact area at a depth of one half the labiolingual dimension of the contact area.

i.

Prepare the proximal chamfer finishing line with an LVS-3 or LVS-4

diamond bur to a depth of one half the labiolingual dimension of the interproximal contact area.

Proximal representation of porcelain laminate veneer preparation before reduction of the proximal subcontact area. The proximal finishing line terminates within the interproximal contact area at a depth of one-half the labiolingual dimension of the contact area because the final porcelain laminate veneer will be significantly different in color from that of the prepared tooth.

ii. Prepare the proximal subcontact area with an LVS-3 or LVS-4 diamond bur.

Proximal representation of porcelain laminate veneer preparation.

8. Prepare the gingival finishing line.

A. For supragingival preparations: Prepare the gingival finishing line to the desired location.

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B. For subgingival margins: Gently place gingival retraction cord . The cord should extend into the sulcus of the interproximal papillae beyond the proximal finishing line 9. Extend the gingival finishing line (for subgingival preparations only) approximately 0.1 mm subgingivally with an LVS-3 or LVS-4 Diamond bur.

Use the pencil line as a guide. Severely discolored teeth may require a 1 -mm subgingival extension of the finishing line.

Properly prepared subgingival finishing line.

10. Round the incisal line angles with an LVS-3 or LVS-4 diamond bur. The thinner LVS-5 or LVS-6 diamond bur may be necessary to access line angles that are close to adjacent teeth.

Teeth prepared for porcelain laminate veneers.

The proximal subcontact area is not visible from this direct frontal view.

Incisal view of the final preparations.

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Clinical Technique 1.

Gently place retraction cord in the sulcus unless previously placed during preparation.

2.

Make the impression with any accurate elastomeric.

LABORATORY COMMUNICATIONS Natural versus Idealized Artificial Appearance Natural teeth are polychromatic and characterized. Canines are usually slightly lower in value or higher in chroma than incisors and premolars. These can be disturbing insights for patients who often desire an idealized artificial appearance (monochromatic, white "chiclets"). Both of these alternatives, and the myriad options in between, should be discussed before a final shade selection is made. It may be helpful to elicit the opinion of the patient's friend or family member.

Shade To achieve the desired shade change, the percentage of opaquing porcelain and the amount of die spacer can be appropriately adjusted by the dental laboratory technician. The specific ratios vary depending on the type and brand of materials used. Close communication with the dental laboratory technician is essential in this regard.

Shape Indicate the desired shape and size of each individual porcelain laminate veneer. As a general rule, feminine teeth are more rounded, less textured, and smaller than masculine teeth; however, this is not always appropriate nor is it always desired by the patient. Therefore specific characterizations should be specified diagrammatically, or in writing, on the laboratory prescription.

Texture 155

Texturing scatters reflected light and produces a more natural appearance. If not all of the teeth in the labial display are to be restored, the laboratory personnel should be instructed to match the texture of the adjacent teeth.

Characterization of Porcelain Laminate Veneers Characterization and polychromaticity of porcelain laminate veneers can be accomplished by the laboratory technician through the use of different shades of porcelain or by surface staining. Additional modifications can also be accomplished by the dentist at the time of cementation through the use of internal color-modifying agents.

A combination of composite resin color modifiers, opaquers, and different shades of luting cements can be layered between the prepared tooth and the restoration to create a polychromatic effect. However, it is difficult to maintain continuity from tooth to tooth with this technique. Even slight variations in the ratios and relative positioning of these agents and differences in the spacing between the porcelain and the tooth surface can influence the final appearance.

This is further complicated because the uncured shade-modifying materials are spread by compression from the seating of the porcelain laminate veneer and not by direct manual placement and subsequent curing before overlaying (as wirb direct composite resin laminate veneers).

Characterization and polychromaticity of porcelain-laminate veneers, including body, gingival, and incisal shading and the degree of opacity, is therefore best incorporated directly into the porcelain by the laboratory technician. The relative thinness of the veneer, however, may limit the extent of polychromaticity attainable in the porcelain. Internal resin shading ideally should be limited to the minor changes that can be accomplished through the use of a single homogeneous shade of luting cement.

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Try-in Considerations: Clinical Technique 1. Inspect the porcelain laminate veneers for cracks and imperfections. Place the veneers on the model and verify appropriate fit individually and collectively.

The porcelain laminate veneers positioned on the laboratory model (labial view).

The porcelain laminate veneers positioned on the laboratory model (palatal view).

2. Remove the provisional restoration with a hemo-stat. Break the brittle composite resin into smaller fragments if it cannot be removed in one piece.

3. Pumice all areas of the prepared teeth (Fig. 9-58). Rinse thoroughly with water and leave wet.

All areas of the prepared teeth are pumiced.

4.

Moisten the teeth and the internal surfaces of the porcelain laminate

veneers with water. Glycerin, a more viscous liquid, may be used if greater retention of the porcelain laminate veneer is desired during this stage.

5.

Place the porcelain laminate veneers on the teeth and evaluate for proper

fit and color. Adjustments to the fit can be made with a fine diamond bur.

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The porcelain laminate veneers are placed on the prepared teeth and evaluated for proper fit and appearance.

6. Verify shade.

A. If the shade is correct: Verify that untinted luting resin will be acceptable by placing untinted water-soluble try-in paste or the actual resin lut-ing cement into the internal surface of the porcelain laminate veneers and placing the veneers on the teeth.

B. If the shade must be altered: Place the appropriate shade of water-soluble try-in paste or the actual resin luting cement into the internal surface of the porcelain laminate veneers and place the veneers on the teeth.

7. Clean the internal surfaces with a cotton-tipped applicator followed by a water spray, and finally in an ultrasonic cleaner with acetone or alcohol. Apply 37% phosphoric acid for 15 seconds to remove any salivary contamination from the etched surface.

8. Clean the teeth again with oil-free pumice ; wash and dry with oil-free air 9. Clean proximal surfaces with a finishing strip ; wash and dry thoroughly with oil-free air.

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Proximal surfaces are cleaned with a finishing strip.

CUSTOM LABORATORY STAINING A large discrepancy in hue or chroma requires custom staining either at chairside or by the laboratory technician. Most laminate veneers are fabricated on a refractory model, which is destroyed when the veneer is removed, so a new model must be fabricated.

Clinical Technique 1. Mix investment material and carefully place a small amount of investment on the lingual aspect of the porcelain laminate veneer.

2. Shape the remaining investment into a block and place the porcelain laminate veneer on this block with the labial side of the restoration facing out.

3. Trim excess investment to completely expose the labial surface. This is best done before the investment sets.

4. Carefully remove the glaze on the buccal surface with a low-speed green stone.

5. Modify the porcelain laminate veneer as necessary and fire .

6. After "bench cooling," carefully remove the porcelain laminate veneer from the investment.

7. Carefully sandblast the internal aspect of the porcelain laminate veneer to remove any remaining investment material.

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8. Try-in the porcelain laminate veneer. If the shade is still not acceptable, repeat steps 1 through 7.

9. Verify with the porcelain manufacturer whether re-etching of the internal aspect of the porcelain laminate veneer with hydrofluoric acid is necessary. Do not allow the etchant to contact the external surfaces.

CEMENTATION Clinical Technique 1. Apply silane coupling agent to the internal surface of all the porcelain laminate veneers according to the manufacturer's instructions.

Placement of a porcelain laminate veneer on an incorrect tooth can easily occur after the luting cement is applied. To avoid this, draw and label circles on the bracket table cover.

Some silane coupling agents require acid etch activation of the porcelain surface.

2. If the tooth surface has been contaminated, pumice the labial and lingual tooth surfaces again.

3. Place matrix strips between the first teeth to be restored and the adjacent teeth.

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Matrix strips are placed between the first teeth to be restored and the adjacent teeth.

4. Etch the enamel and dentin for 15 seconds

The enamel is etched with 37% phosphoric acid for 15 seconds.

5. Wash with water and or water/air spray for a minimum of 10 seconds for gel or liquid etchants.

The etchant is removed with water.

6. Air dry. Repeat the etching process and rewash the enamel if it is not "frosty" white. Repeat if necessary.

7. Place new matrix strips between all interproximal areas.

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8. Rewet the dentin with a cotton pellet.

9.

Apply bonding agent to the internal surface of the porcelain laminate

veneers according to the manufacturer's instructions.

10. Apply preselected shade of luting cement to the internal surface of the porcelain laminate veneer.

11. Place dentin/enamel bonding agent onto the tooth according to the manufacturer's instructions.

12. Carefully place the porcelain laminate veneers onto the teeth and fully seat to place.

13. Hold the porcelain laminate veneer in place and cure the incisal tip from a labial direction for 10 seconds.

The restoration is carefully seated onto the prepared tooth and the incisal tip is cured from the incisolabial direction for 10 seconds.

14. Remove excess luting cement with a sable brush moistened with bonding agent.

15. Cure the remaining luting cement from the buccal, lingual, and incisal directions according to the man-facturer's instructions.

16. Remove the matrix strips.

17. Remove excess flash with composite resin carving instruments.

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18. Repeat steps 2 to 17 for the remaining porcelain laminate veneers. Two adjacent teeth can be placed simultaneously.

FINISHING AND POLISHING Marginal discrepancies immediately after cementation of indirect restorations are, to some degree, inevitable. Postcementation intraoral finishing of both porcelain and resin at the tooth-restoration interface can be accomplished with rotary instruments. Scanning electron microscope and spectrographic reflectance analyses reveal that adjusted porcelain can attain a surface smoothness that is superior to that of glazed porcelain if a specific protocol is followed." This protocol is outlined below and involves the use of progressively finer abrasives. Finishing and polishing instruments include diamond burs, a 30-fluted carbide bur and a 2Âľm to 5Âľm particle size diamond polishing paste on a webbed rubber prophylaxis cup.

Clinical Technique 1. Carefully finish the facial margins with the Ml finishing diamond in a highspeed handpiece at low speed (regulated by applying appropriate pressure on the rheostat) with water coolant.

2. Finish the lingual areas with a fine "football-shaped" diamond.

3. Dry the marginal areas to evaluate for smoothness and repeat steps 1 and 2 if necessary.

4. Evaluate the occlusion with articulating paper in both centric occlusion and in all eccentric excursions. Adjust porcelain, if necessary, with an extra-fine "football-shaped" diamond bur.

5. Repeat steps 1 through 4, substituting first an M2 finishing diamond, then an M3 finishing diamond, and lastly, a 30-fluted carbide bur.

6. Finish and polish the proximal areas with interproximal abrasive strips.

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The proximal areas are finished with finishing strips.

7. Evaluate the interproximal contact areas with unwaxed dental floss and repolish if necessary.

8.

Polish with a diamond polishing paste on a prophylaxis cup using

intermittent pressure to prevent heat buildup.

9. Reevaluate the finishing and polishing procedures in approximately 1 to 2 weeks for additional mar-ginal discrepancies that may have been obscured by gingival bleeding or may result from subsequent water sorption by excess luting resin.

The final porcelain laminate veneer restorations.

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CERAMIC INLAYS Indications for ceramic inlays: 1. Patients who maintain good oral hygiene.

2. Patients requesting for tooth colored restorations in posterior teeth.

3. In the cervical regions and proximal regions of anterior teeth where esthetics is of prime concern.

4. Teeth in which strengthening of the remaining tooth structure is needed.

5. No evidence of excessive attrition in relation to the patientâ&#x20AC;&#x2122; s age.

6. Cavity free from marked undercuts.

7. Ideally where all cavity margins are in enamel.

8. Sufficient tooth structure is available for bonding.

9. Lesions on the occlusal and proximal surfaces of posterior teeth.

Contraindications: 1. It is not a restoration of choice if an anterior tooth is grossly involved either proximally or cervically. There must be adequate tooth structure to support the restoration.

2. When access to the lesion is poor and overcutting of tooth structure would be required Eg in rotated teeth. In such conditions other restorations should be considered.

3. Patients with poor oral hygiene and inadequate motivation.

4. When short teeth preclude developing adequate resistance and retention forms Eg: Heavily worn down teeth.

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5. Teeth with insufficient tooth substance for bonding.

6. Preparations with excessive undercuts 7. Where adequate isolation is not possible.

8. Teeth with large pulp chambers, which limit the reduction of tooth structure.

9. Where posterior group function and reduced vertical dimensions apply strong lateral forces on the restorations.

Advantages of ceramic inlays: 1. Good esthetics 2. Low thermal conductivity 3. High tolerance of the soft tissue to its presence.

4. Chemically inert and relatively insoluble in oral fluids.

5. A coefficient of thermal expansion close to that of the natural tooth.

Disadvantages: 1.

Increased cost and time for fabrication when compared with a direct restoration.

2.

Technique sensitive Restorations usually require a high level of operator skill.

3.

Require special and expensive laboratory equipment.

4.

Restorations made from porcelain are brittle and can fracture if inadequate thickness is present to resist occlusal forces.

5.

Fractures can occur during try in or post cementation.

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6.

Because of their very high hardness, they can cause abrasion of opposing teeth or restorations.

7.

Lack of perfect adaptation to cavity walls exposes the cement line.

Differences in cavity preparation for gold inlay and ceramic inlay: Bevel: a) No cavo surface bevel done for porcelain inlay, butt joint cavosurface margin for porcelain. b) For gold inlays,300 to 450 cavosurface bevel is prepared.

Taper: a) For porcelain inlays, greater taper 60 to 80 per each wall is needed as very little pressure is to be applied for try in. b) For gold inlays, 20 to 5 deg taper per each wall is made.

Internal line angles and point angles: a. For porcelain inlays, these angles should be well rounded to prevent stress concentration. b. For gold inlays, the internal line angles could be definite but not rounded.

Pins: a) For porcelain, no pins are used. b) For gold castings parallel pins could be used.

Ceramic inlays can be classified into four different groups according to their material composition and fabrication:

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a) Ceramic inlays produced on refractory die. b) Cast ceramic inlays. c) Machined ceramics. d) Inlays fired on a platinum foil All ceramic inlay restorations based on their fabrication can be classified as: 1. Conventional powder slurry ceramic. a) Optec HSP- Leucite reinforced porcelain b) Duceram LFC- Hydrothermal low fusing porcelain 2. Pressable ceramic Classification of Ceramic inlays: a) IPS Empress b) Optec pressable ceramic.

3. Infilterated ceramic a) In ceram.

4. Castable ceramic a) Dicor b) Cera Pearl.

5. Machinable ceramic a) Cerec Vitablocs Mark I and II. b) Celay blocks.

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c) Dicor MGC. The refractory die technique uses a direct build up of porcelain onto an investment model whose coefficient of thermal expansion is similar to that of ceramic material.

Atleast three firings are generally necessary to compensate for firing shrinkage before a final glaze is applied.

This method eliminates the use of platinum foil, which in part causes inaccuracy and deformation.

Procedure:  After the cavity has been prepared, an impression is taken and a master working cast is poured in die stone or epoxy resin. Die pins aid in forming a die.  The master cast is separated and trimmed. A die spacer is applied to the cavity preparation usually on the pulpal and axial walls.  The prepared master model is then duplicated with a silicone impression and poured in the refractory investment capable of withstanding porcelain firing temperatures.  After hardening the cast is fired at 1000 deg C to eliminate decomposition gas which may be generated during the first porcelain firing.  It is then soaked in a conditioning solution until completely saturated.  This solution enables the porcelain contraction to be directed towards the cavity itself.

Ceramic inlays produced on refractory die

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 Dental porcelain is added into the cavity preparation on the refractory die and fired in an oven.  A two to three step build up technique is necessary to compensate for the sintering/ firing shrinkage.  The ceramic restoration is retrieved from the die, cleaned and seated on the master die for adjustment and finishing. Occlusal contacts are adjusted and proximal overhangs if any are removed.  After an accurate finishing of the margins, the product can be finally glazed.  The restorations fabricated with this technique must be carefully handled during the try in to avoid any fracture. Etching is done on the restoration’s cavity surface followed by application of luting agent for cementation.

Advantage: 1. Relatively less expensive set up.

2. And compatibility with most existing ceramic ovens used in the laboratory.

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Disadvantages: 3. Technique sensitivity 4. Higher incidence of fracture compared to the other ceramic systems.

5. Problems may be encountered in the fit and marginal integrity of these restorations.

Preparation design: 1. Occlusal reduction, 2. Axial reduction, 3. Types of margins, 4. Internal form and finish, 5. Treatment of dentin, 6. Taper and extension, and 7. Cuspal preparation / reduction.

Occlusal reduction: Approximately 1.5 mm to 2 mm of occlusal reduction is done for all ceramic systems.

Axial reduction: Cerapearl material needs 1.5 mm of reduction.

Cavity preparation for posterior ceramic restoration: Color match with the tooth structure, which makes the interproximal extension undetectable.

When entire cusps are fractured and require replacement, the facial or lingual finish lines may be carried to within 0.5 mm of the gingival tissue to provide a harmonious blend of tooth color.

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Cuspal reduction/ preparation: Cuspal preparation and extension is needed when a cusp has fractured or is hopelessly undermined. Cuspal capping must also be considered when the margin of an inlay approaches to within 1.5 mm of a functional cusp.

In functional cusp, the ceramic thickness required to avoid critical strain should be 1.5 mm for premolars and 2mm for molars.

In non functional cusp 1 to 1.5mm seems adequate.

These are ceramic inlays produced by the lost wax technique. Theoretically these inlays have improved fit compared to those restorations built on investment materials. These products are supplied as solid ceramic ingots, which are used for fabrication of cores or full contour restorations using a lost wax and centrifugal casting technique.

Generally, one shade of material is available, which is covered by conventional feldspathic porcelain or is stained to obtain proper shading and characterization of the final restoration.

Glass ceramics are polycrystalline solids produced by the controlled crystallization of glasses. Compared with the conventional dental porcelains used for all ceramic restorations, castable glass systems offer great promise because of ease of fabrication and low processing shrinkage. Thermal processing ( Ceramming) is necessary to produce sufficient crystallization to increase strength, opacity, resistance to abrasion, thermal shock resistance to abrasion, thermal shock resistance and chemical durability while maintaining adequate translucency and polishability.

Micor glass containing tetrasilicic acid, because of their flexibility and platelike morphology, provide resistance to fracture propogation. This material is used in new glass ceramic called Dicor.

Castable ceramic inlays: 172

 Tooth preparation recommendations:  Minimum reduction : 1mm.  Recommended axial reduction: 1.2 to 1.5 mm.  Incisal or occlusal reduction: 1.5 to 2 mm.  The degree of taper recommended : 6-8 degrees.

Procedure:  After tooth preparation, impression procedures are applied and a master working cast in improved die stone or epoxy resin is poured.  Tooth shaded die spacer is then chosen from the shading chart and applied in two thin coats avoiding the margins. Die lubricant is applied directly over the die spacer, and a wax pattern is made using conventional technique.  Occlusal detail can be carved into the pattern and retained throughout the subsequent process. The completed wax pattern is sprued usually with an eight guage sprue..  Length of the sprue should be such that the pattern is positioned ¼ th to 1/8 inch from the top of the ring. The sprueing technique uses a long casting ring( 13/16 inches) and a generous reservoir to ensure complete emptying of the molten glass into the mould during casting.  The sprued pattern is invested in a double- lined ring with a phosphate bonded investment. After burning out and heat soaking at 900 Deg C for atleast 30 min, the glass is cast centrifugally at 1370 Deg C. The cast ceramic is supplied in premeasured sizes, sealed in a disposable crucible.

Dicor (Castable glass ceramic)

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ď&#x192;&#x2DC; Following divesting and grit blasting with 25 micro meters alumina grains, the inlay is embedded in a special investment and cerammed to produce crystal growth. ď&#x192;&#x2DC; The resulting inlay is semicrystalline yet translucent, so that it may be covered by surface glazes. The strength of Dicor is similar to aluminous porcelain.

Advantages: 1. Excellent marginal fit.

2. Relatively high strength.

3. Surface hardness and occlusal wear is similar to enamel.

4. Excellent esthetics resulting from natural transulency.

5. Inherent resistance to plaque accumulation (seven times less than on the natural tooth surfaces.

Disadvantages: Chances of losing low fusing felspathic shading porcelains, which have been applied for good shade matching.

Castable apatite ceramic was first developed by Hobo and Bioceram group. Its casting once obtained has and amorphous structure but when subjected to ceramming, crystalline oxylapatite results which is chemically unstable and forms crystalline hydroxylapatite on exposure to moisture. Compared to normal enamel Cerapearl show somewhat irregular arrangement which is responsible for its superior mechanical properties. Because the crystalline content is similar to natural enamel, Cerapearl is expected to be biocompatible. The Youngâ&#x20AC;&#x2122;s modulus, tensile strength and compressive strength of Cerapearl is appreciably higher than conventional porcelains.

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Castable apatite ceramic (CERA PEARL)  Tooth reduction: For Class I and Class II inlays, the desired reduction is 2 mm on the occlusal surface and 1.5 mm from the proximal surface.  Class III and Class V inlays are not subjected to much forces, hence do not need more than 1.5 mm thickness.  The sprued wax pattern which is attached to the ceramic crucible on other end is located in a preformed silicone mold. The investment is mixed for one minute under vacuum and poured into the silicone mold.  After sixty minutes, the silicone mold can be easily separated from the set investment. The ringless investment( phosphate bonded) is then dried in an electric Oven at temperatures :  Less than 100 degrees for atleast 30 min.  Over the next 30 min the temperature is then raised to 500 degrees C.  Finally, the oven temperature is held at 800 degrees C for 30 min  The investment mold is then transferred to high heat processor. 8- 10g of raw Cerapearl is placed in the ceramic crucible, melted at 1460 deg C. under vacuum and cast into the mold.  After the casting process is completed, the ring is removed from the processor and transferred into the crystallization oven.  Crystallisation makes the casting highly dense and turns it into a more stronger, harder and chemically stabler structure.  The crystallization process is started at 750 Deg C and the temperature maintained for 15 min. Oven temperature is then raised at 50 Deg C per min until the temperature of 870 Deg C is reached. After one hour at this 175

temperature, sufficient amount of crystal formation occurs. Above 870 Deg C., crystals grow excessively and result in too white an appearance.  The investment ring is removed from the oven and cooled to room temperature. The casting is divested and cleaned, sandblasted, sprue is cut and then smoothened with a carborundum stone. Cera Pearl should always be seated with light finger pressure, and the final adjustments done with diamond points.  The crystallized Cera Pearl is very white hence requires an external stain application.  Glass ionomer cement is considered the best choice for a luting agent, because it would adhere to both the restoration and the tooth. Cera Pearl is made conducive to adherence to glass ionomer restoration by a process called Activation.  Activation is a process by which a casting is treated mechanically and chemically to improve its bond to the tooth structure. The cavity surface of the restoration is sandblasted with 20 micrometer alumina powder and cleaned in an ultrasonic bath.

Acetone is used to remove any oil residue. Chemical activation is done by applying a liquid UHK 001 for 5 minutes. It is then rinsed away with distilled water, and the restoration subjected to heat at 140 Deg C in an oven for 10 min.

After cooling to room temperature the restoration is ready for cementation. The activation process aids in adhesion by liberating calcium ions from apatite and these form hydrate bonds.

This system was first described by Wohlwend et al in 1989 and became commercially available as IPS empress and Optec OPC.

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This system also utilizes the lost wax technique but differs from the earlier described castable ceramics in that the material is pressed into the mold under pressure and not centrifugally driven.

Here also, a wax pattern of the proposed restoration is first fabricated and then invested in a phosphate bonded investment material.

Pressable ceramic inlays: Following the burnout procedure, the ring along the investment is placed in a specialized mold that has an alumina plunger. The ceramic ingot is placed under the plunger, the entire assembly is heated to 1150 deg and the plunger presses the molten ceramic into the mold.

The final surface of the restoration is adjusted by surface staining or veneering.

In the veneering technique, the original wax up is cut back by 0.3 mm. After moulding and baking have been carried out, the feldspathic porcelains are then added on the surface to obtain full contour and the correct shade.

In some cases, the pressed core itself is grounded to produce a core, which represents the dentin onto which incisal porcelain and glaze are added.

When using the lost wax technique, the total shrinkage is reduced as the only shrinkage, which occurs is during cooling, that can be controlled with an investment having an appropriate expansion.

Advantages:  Lack of metal or opaque ceramic core.  Moderate flexural strength, less susceptible to fatigue failure than conventional porcelain.  Excellent fit.  Excellent esthetics.

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Disadvantages: ď&#x192;&#x2DC; Potential to fracture in the posterior areas. ď&#x192;&#x2DC; Need for special equipment( pressing oven and die materials.)

Procedures for heat pressed ceramic Procedures for heat pressed ceramic

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 After 1988, machined restorations have gained popularity.  Two principal machining approaches for dental restorations:  The various types of ingots used for the purpose are as follows:  Cerec Vitablocs Mark I:

Was the first composition used with Cerec

system. Its composition, strength and wear characteristics are similar to the feldspathic porcelain used in PFM restorations.  Cerec Vitablocs Mark II: This is a high strength feldspathic porcelain and has a grain size finer than Mark I composition. There is less abrasive wear of the opposing tooth with this material.  Dicor MGC: This is a glass ceramic with fluorosilicate mica crystals in a glass matrix. Its flexural strength is higher than castable Dicor.  Celay: It is a fine feldspathic porcelain with a composition which manufacturers claim is similar to Cerec Mark II. On this basis, the physical and clinical properties of the two can be expected to be similar.

Analogous systems: Copy milling technique/ Grinding technique: a) Automatic ( CeramaticII ) b) Manual( Celay) Erosive technique.

Digital systems: CAD CAM technology Machined ceramic inlays:

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In this technique, it is possible to mill a restoration form ceramic materials using special systems like Celay, Ciromatic II. The best known copy grinding system is Celay (Mikrona , Switzerland), which was introduced commercially in 1991.

The copy milling technique is based on the idea of first fabricating a prototype inlay (Pro inlay) using a resin or wax pattern of the fabrication, which is then copied using a scanning tool or micropalpation method. The final restoration is then milled from a preformed ceramic block.

Any cavity preparation for porcelain restoration should be free of undercuts.

One approach is the removing of undercuts but this would involve large destruction of sound tooth structure. A more conservative approach is the blocking of the undercuts in the cavity by using a resin modified glass ionomer on the die if an indirect method is used.

The proinlay is fabricated with a blue resin based composite made either directly on a prepared tooth or indirectly on a die made from the impression.

The prototype is fixed into the Celay unit. As the surface of the proinlay is scanned with tracing tool, a coarse diamond coated disc( 124 mm grain size) simultaneously roughs out the shape of a ceramic restoration. A fine white powder is applied to the proinlay and the scanning is done again using a smooth disc and fissured and tapered burs.

Matching fine diamond discs and burs refine the shape of the gross restoration.

Once the white powder has been completely traced off, the milling of the ceramic restoration is considered complete.

Stains and glazes may be added to the inlay before etching and silanized.

The time taken to mill the restoration depends on the experience of the operator, complexity of the restoration and sharpness of the cutting disks. The average time for milling is 20 to 30 min.

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Copy milling: Disadvantage: One problem frequently encountered during the use of copy milling technique is the difficulty in obtaining accurate proinlays.

Ultrasonic/ Sono erosion (DFE, Erosonic) used for grinding ceramic requires a metal based negative form of the interior and exterior contours of the restoration, which are produced by wax moulding and casting or by intensive copper plating of the impression.

These are called Sonotrodes. Both sonotrodes fitting exactly together are guided into a ceramic blank after connecting to an ultrasonic generator under slight pressure.

The ceramic blank is surrounded by an abrasive suspension of hard particles such as boron carbide, which on acceleration by ultrasonics erodes the restoration of the ceramic block.

Mormann and Brandestini for the first time used a CAD-CAM device to digitize and store cavity parameters, and a copy milling device to then shape out a restoration out of the ceramic block. This method was commercially available as an integrated CAD-CAM unit for dental use in 1988 by Siemens, known as Cerec. The original system was known as Cerec I when in September 1994 an improved version Cerec II was introduced. The unit consists of 1.

Three dimensional video camera ( scan head)

2.

An electronic image processor memory unit.

3.

A processor which is connected to a miniature milling machine.

Cerec I cannot prepare the occlusal anatomy of the restoration whereas Cerec II can. In addition to the grinding wheel, the Cerec II is also equipped with a

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cylindrical diamond stone which is able to finish off undercuts at buccal extensions, curved shoulders at Erosion method: CAD- CAM generated inlays: Cuspal preparations and the proximal areas. Also Cerec II is a definite improvement over the Cerec I comparing the camera and image processing systems.

Briefly CAD- CAM system uses digital information about cavity preparation or a pattern of the restoration to provide a computer aided design( CAD) on the video monitor for inspection and modification. Once the three dimensional image of the restoration is accepted, the computer translates the image into a set of instructions to guide a milling tool (Computer Assisted Manufacturing CAM) in cutting the restoration out of the ceramic block. In a way, the computerized unit serves as an automated mini dental lab.

Cavity preparation for CAD-CAM inlays:  Tooth preparation for CAD-CAM inlay or an onlay requires conventional cavity design with slight modifications:  No convexities should be present in the pulpal and gingival walls. They may be flat or concave buccolingually.  The occlusal step should be prepared 1.5 to 2 mm in depth and any isthmus or groove extension should atleast be 1.5 mm wide to decrease the possibility of fracture of the restoration.  The buccal and lingual walls of the occlusal portion of the preparation may converge towards the occlusal. This feature is unique to the Cerec system as it can automatically block out any undercuts during the optical impression. A more conservative cavity preparation is therefore

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permissible along the occlusal aspect, especially when replacing the old amalgam restoration when undercuts were purposefully given in the restoration for retention. The facial and lingual walls of the preparation in the proximal box are prepared in the usual fashion with slight divergence toward the occlusal. Convergence is not given here so as to avoid excessively thick composite cement lines.  Axial walls should be straight and not follow the convex contour of the proximal surface of the tooth.  No cavosurface or marginal bevels should be given.

Technique: Five steps for fabrication of CAD- CAM fabricated inlays:  Computer surface digitization  Computer aided designing.  Computer aided manufacturing.  Computer aided esthetics.  Computer aided finishing.

The last two steps are very difficult and hence not a feature of the commercial systems available.

Surface digitization: Optical impression is used to collect the information in the shape of the preparation using a Scanning device. The image is displayed on the monitor and camera orientation is corrected accordingly. Repeated optical impressions are taken until the most ideal impression is found and stored in the computer.

Scanning devices:

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Mechanical Optical (infrared video camera).

The optical sensors are not able to measure highly transparent or reflective surfaces and so enamel has to be covered with a powder or a water soluble colout.

The mechanical scanning produced by a profilometer or a sensor is very precise, but has several limitations.

The scanning tip produces errors in measurement on steep flanks( cusp slopes) and distorts easily. Undercut areas and narrow gaps like fissures also cannot be explored and have to be blocked out.

The 3 D scanning devices can be applied either directly onto the tooth or indirectly onto a model fabricated from an impression of the cavity or a proversion.

The advantages of the direct technique:  The cavity preparation to bonding, the entire procedure is completed in one session and eliminates the need for impressions, stone casts and dies and hence associated inaccuracies.  Adjustments are done in the mouth obviating the need for opposing cast and articulator mounting. Laboratory procedures are not usually required.  No interim restorations are required, the chances of lost temporaries and sensitivity between appointments is greatly reduced.

Disadvantages of direct technique:  Waste of expensive chairside time in case of a difficulty during milling or designing.

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ď&#x192;&#x2DC; Time required in chairside is increased since adjustments and polishing are to be done at the chairside.

Indirect method of scanning: ď&#x192;&#x2DC; An impression of the prepared tooth as well as adjacent teeth is taken in elastomeric or hydrocolloid impression materials. ď&#x192;&#x2DC; The impression is poured in die stone and a split cast model is made.

Temporization Needs to be done is between appointments, with Duraseal best serving the purpose. It is autopolymerizing polymethylmethacrylate resin with plasticizers available as powder liquid system, mixed and applied directly onto the tooth without a cementing medium. It does not contaminate the bonding surfaces and also does not

require shaping or adjustment. Because material contains

plasticizers, it remains elastic throughout the temporization period and it is easy to remove at a later stage.

Computer aided Designing: This step involves three dimensional image processing. The operator enters data and confirms the features of the preparation like boundaries of the restoration, position of the gingival margins, proximal contacts and contours, buccal and lingual extensions. The collected data is further processed by curve smoothening and if necessary by data reduction. Undercuts can be blocked at this stage.

Computer Aided Manufacturing: The cavity surface of inlays, onlays are milled to the dimensions of the scanned image with diamond disks or other instruments that are electrically driven and lubricated with water. The occlusal surface cannot be ground with Cerec I but the occlusal surface can be ground with Cerec II. The occlusal anatomy when

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using CEREC-1 is

completed later by the operator using diamond burs.

Controlled cutting of the ceramic is done by: rotation of the block; horizontal movement of the block into the wheel and vertical movement of the cutting wheel. The fit of the restoration is confirmed in the patient’s mouth and any necessary adjustments made. Proximal contours

and contacts can also be

provisionally adjusted.

At the cementation visit rubber dam is applied and the fit of the inlay is verified on the tooth. Proximal adjustments are done with abrasive diamond disks that run from coarse to fine. Proximal surfaces are adjusted at this stage itself, as these would be difficult to be reached later.

The inlay is then prepared for bonding which includes preparation of both the restoration and the tooth. Etching is done on the cavity surface of the inlay either with a microetcher and/ or ammonium bifluoride or hydrofluoric acid.

After etching, a silane bonding enhancer is painted onto the surface Surface of the preparation of the tooth follows the usual procedure. The cavity surface is etched for 15- 30 sec with 30% phosphoric acid. Depending on the bonding system used, the appropriate primer and the bonding agent are applied to the tooth surface.

The cementation procedure and subsequent finishing and polishing are similar to as in other ceramic inlays. Glazing may not be required in these restorations.

Disadvantages of the CAD-CAM system:  Initial high cost for the purchase of the ceramic unit.  Time and cost must be invested to master the technique.  Contouring the occlusal surface may still have to be carried out by the clinician.

Cerec –III

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This system simplifies and accelerates the fabrication of ceramic restorations compared to the former systems. It accommodates advances in computer technology thus allowing numerous simplifications and increased automation.

Cerec III software simplifies occlusal and functional registration. Proper occlusion is established accurately and quickly, manual adjustment is reduced to a minimum.

The separate branding device, which provides greater detail and is fitted with two finger cutters is connected via radio control wave to control unit.

The grinding unit receives data from the control unit independent of its location in the practice. The second restoration can be designed when the first is being milled. The grinding unit is also equipped with a LASER scanner and can be used for indirect applications through a personal computer. Since it is equipped with an intraoral video camera or a digital radiography unit, it can also be used for patient education and for user training.

Cicero system for fabrication of ceramic restorations (Cicero Dental Systems B.V.( Hoorn, The Netherlands) The Cicero (Computer integrated ceramic reconstruction) method for producing ceramic restorations uses optical scanning, ceramic sintering and computer assisted milling techniques to fabricate restorations with maximal static and dynamic occlusal contact relations.

The technique consists of optimally digitizing the die, designing the crown layer build up, and subsequent pressing , sintering and milling consecutive layers of a shaded high strength alumina core material, a layer of dentin porcelain, and a final layer of incisal porcelain. Final finishing is performed in the dental laboratory.

The Cicero system allows efficient production of all ceramic restoration without compromising on the esthetics and function.

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Cementation of the inlay: The luting of semidirect or indirect restorations implies a double bond:  Between luting composite and the tooth,  Between luting composite and ceramic or composite inlays Bond between luting composite and the tooth: Successful marginal adaptation is achieved when enamel completely surrounds the preparation limits. When free marginal dentin exists, application of modern dentin bonding agent and resin base is advisable.

Bond between luting composite and ceramic or composite inlays:  Luting composite to ceramic bond enhanced by ceramic etching with hydrofluoric based acid and silanization.  Luting composite to composite inlay bond is enhanced by roughening the internal surface with coarse diamonds or sandblasting.

Finishing and Polishing of Ceramic and Porcelain inlays: Finishing:  30 micrometers diamond.  30 to 20 micrometers tungsten carbide bur.

Polishing: 1. Diamond impregnated polishing gel( Two striper MPS, Premier dental products, USA.) 2. Diamond impregnated felt wheel( Diafix oral, Mueller Dental, Germany)

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3. Diamong impregnated rubber polisher( Brassler, Savannah.)

4. Silicon carbide polishing system( Ceramiste, Shofu, Kyoto, Japan).

Composite inlays could be polished with multifluted carbide burs, the gingival margins finished in a traditional manner with aluminous or glass metal strips.

Low fusing ceramics or machinable ceramics can be easily polished with flexible discs, fine diamond burs, silicone points containing aluminium oxide or silicon carbide and special aluminium oxide polishing pastes. For others finishing procedures should be adjusted to occlusal adjustments since they are difficult to polish. Use of diamond points followed by silicone points produce smoother surface.

Master model with die spacers Hard stone dies replicated and refractory die produced. Two porcelain inlays are shown at the completion of stratification and modeling. During the last firing the surfaces are characterized and glazed Specific procedures for cast ceramic restorations

Modeling the future restoration with wax and preparing it for casting.

Specific procedures for Conventionally fired porcelain

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The casted restorations, in glassy state, they appear totally transparent.

The restorations then subjected to thermal ceramization process after which final glazing and staining done

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The CAD systems

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ESTHETICS WITH PERIODONTICS Esthetic dentistry is constantly evolving in terms of materials, techniques and its conceptual understanding. In the context of the latter, the "periodontal" perspective of esthetic dentistry has gained wide acceptance over the years. A thorough knowledge of the principles behind the harmonious interrelationship of the pink with the 'white' is imperative for all esthetic dentists.

The presence of a sound and healthy periodontium is undoubtedly a must before undertaking any restorative procedure; but besides restoring the diseased periodontal infrastructure to health, there are a variety of esthetic periodontal defects like recessions,

inadequate

crown

lengths,

hyper-pigmented

gingiva

and

open

interproximal spaces, which require correction. Recognition of these esthetic mucogingival problems and a treatment plan for their correction are the prerequisites for esthetic success in restorative rehabilitation.

Therefore, a precise implementation of these procedures in this emerging field of perio-esthetics mandates a complete understanding of all periodontal principles and its applications to achieve a perfect esthetic therapeutic outcome.

Esthetic periodontal considerations A healthy periodontal environment with sufficient tissue volume to fill in the interproximal spaces is an essential element for ideal anterior esthetics. The gingival tissues are visible during smile, laughter and even speech, as a result, any normality or abnormality of the gingiva can be easily appreciated.

A healthy periodontium with an ideal gingival scallop and knife edge contour.

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The normal esthetic and periodontal considerations are as follows: Shape and position of the gingiva: The marginal gingiva is important as its form, texture and heights of contour (gingival zenith) create a proper interface between the pink and the white.

In an ideal esthetic relationship, the position of the gingival margin is dictated by the vertical limits of the active smile, the gingival margins of the maxillary central incisors and canines positioned at the vermilion border of the upper lip. The gingival margin of the lateral incisors is usually located 1 to 2 mm more incisally or at the same height of the central incisors and canines.

The gingival zenith is distal to the long axis of the tooth for both the maxillary central incisor and canine while it is situated on the long axis of the tooth for the maxillary lateral incisor. Many variations are seen in this pattern but whenever the lateral incisors are placed more apical to the central incisors and canines, then it is perceived as an unaesthetic gingival pattern.

The tooth shape, the inciso-gingival length and the mesio-distal width to a certain extent guide the gingivai position in natural dentition. The left and right side symmetry of the gingiva is essential to avoid visual discrepancy between the contralateral teeth.

The degree of scallop of the gingival margin depends on the periodontal morphotype.

Thick morphotypes have flatter gingival contours and thin morphotypes have more scalloped gingival contours. The gingival height of contour of the premolars and molars lies in a more occlusal position as it moves posteriorly.

The horizontal limits as well as the vertical limits of the smile should be evaluated.

Most patients show the maxillary teeth with or without the gingiva upto the first molar in an active smile. To provide for proper depth and harmony of the smile, the gingival display should be consistent and proportional from tooth to tooth, from the left first molar to the right first molar.

Embrasures: In healthy periodontium the interdental papilla blends into embrasure spaces completely from buccal to lingual which is an important esthetic factor assur-

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ing harmony in the dental composition. However, in cases of recession or postperiodontal therapy the embrasures may open up revealing a black triangle.

The apical location of the interdental papilla creates a black triangle effect between the upper left central and lateral incisors.

Biologic width: It has been demonstrated from autopsy recordings that the mean sulcus depth is 0.69mm, mean length of the junctional epithelium is 0.97mm and connective attachment is 1.07mm; the combined width of the latter two is 2.04 mm and is called the 'biologic width'. This biologic width is always present, therefore restorative margins must maintain a distance from the alveolar crest that respects the biologic width, otherwise gingival recession or pocket formation ensues.

Esthetic periodontal defects and its correction Periodontal defects posing an esthetic problem can be addressed once the patient is adequately motivated in periodontal health maintenance and demonstrates efficient plaque control. These defects may include: • Violations of biologic width.

• Gingival asymmetries.

• Excessive gingival display.

• Localized gingival recessions.

• Abnormal frena.

• Excessive gingival pigmentation.

• Inadequate interproximal papilla.

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"Biologic width" considerations during restorative procedures The dentist should consider the following aspects to esthetically plan procedures involving re-establishment of the biologic width. â&#x20AC;˘ Location of the restorative margins. â&#x20AC;˘ Location of the gingival margins. â&#x20AC;˘ Location of the crestal bone.

Restorations which are over-extended in the cervical region should be carefully removed and proper cleaning of the teeth is recommended with excavation of deep carious lesions in the cervical region. Provisional restorations should then be fabricated with proper contouring in the cervical region. The pockets should be probed and isolated areas of excessive bone loss should be marked and regenerative procedures instituted.

Severe recession in relation to the left central and lateral incisors due to the violation of biologic width by the margins of the crowns.

Periodontal debridement after removal of the crowns.

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Interim restorations placed after periodontal correction. Note the reduction in the interproximal space between the central and lateral incisors.

Violation of the biologic width in relation to the right central incisor. Note the severe circumferential redness with absence of recession.

Osseous reduction and suture placement to correct violation. Interim restoration placed in harmony with the gingival margin.

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Healing after 6 weeks of interim restoration placement.

Full ceramic crown placed as a final prosthesis. Note the restoration of the healthy gingival margin.

In cases of restoring teeth with a healthy periodontium after the exact position of the restoration margin is decided, the position of the gingival margin is surgically established Surgical technique for establishing proper biologic width involves recontouring the osseous crest so that a minimum of 3mm of the flap can be placed coronal to the position of the recontoured osseous crest. This will take into consideration the average biologic width of 2mm. Sometimes a loss of 0.25mm0.5mm of crestal bone can be anticipated due to surgical trauma. In cases of thick gingiva with thicker bone the bone loss can be minimal however in cases of thinner bone and thin gingiva as in the lower anterior region, greater bone loss can be anticipated. A minimum of 6 weeks of healing is required before final restoration can be placed.

In accidental tooth fractures or any other clinical situations where the restorative margins may violate the biologic width, bone removal in the adjacent teeth might be

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necessary to get desired esthetic result. We should have a thorough understanding of the esthetic patterns of the gingiva to determine the exact location of the margins to establish a good end result.

Gingival asymmetries Whenever the facial gingiva of the anterior teeth does not follow a symmetrical pattern, crown length discrepancies are perceived; some teeth appear longer while others appear shorter. Correcting these discrepancies to an esthetic gingival pattern becomes the main goal of the esthetic or restorative dentist The possible causes of gingival asymmetries are: • Gingival hyperplasia.

• Altered passive eruption.

• Tooth or teeth malpositioning.

• Overzealous tooth brushing.

• Periodontal disease.

As a combination of causes can be present in a single clinical situation, the dentist should consider various etiologies before selecting the appropriate corrective procedure for gingival asymmetries. Adequacy of attached gingiva, root exposure, type of restoration planned and root length should be some of the factors considered in treatment planning.

Whenever multiple teeth are involved, a comprehensive esthetic mapping of the gingival position is recommended. The surgeon can plan individual tooth procedures considering the end result anticipated by the restorative dentist.

Technique for correction: After administration of anesthesia, gingivectomy is performed first to correct the disparity between the adjacent teeth. Then using a periodontal probe, determine the distance of the bone from the newly achieved gingival margin. In cases where the probing depth is 3mm or more, then no osseous reduction is required. However, in cases where the probing depth is less than 3mm,

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then to maintain the biologic width, osseous reduction is carried out, wherein a labial and palatal flap is raised and osseous reduction is done all over including the interproximal region using low speed round carbide of known diameter with copious irrigation and the flap is then sutured back.

The gingival tissue is excised using a B. P blade number 15 to correct the asymmetrical gingival margins in relation to the left maxillary cuspid and bicuspids.

Gingivectomy is performed to the desired limit.

A full thickness flap is raised and osseous reduction is carried out using a low speed hand piece and round carbide bur.

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Gingival asymmetry between central incisors.

Using a number 12 B.R blade the gingival tissue in relation to the left central incisor is excised to the level of the right central incisor.

A full thickness flap is raised.

With the help of a low speed hand piece and carbide bur, osseous reduction is carried out.

The flap repositioned back into place using sutures.

Postoperative frontal view after the placement of veneers.

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In cases of a single tooth gingival asymmetry where crown lengthening with minimal osseous reduction is indicated, a technique is described wherein after the gingivectomy is carried out, two vertical incisions are made on the gingival margins without involving the interdental papilla. After raising the flap the osseous reduction is carried out. While contouring the bone, care should be taken to avoid any ledge formation in the bone crest.

Crown lengthening can be done either for esthetic or functional purposes: Esthetic crown lengthening: When a disparity in the clinical crown length exists between contralateral teeth resulting in a left / right side height discrepancy, esthetic surgical correction can be provided to enhance the cosmetic result before restorative measures.

In such cases 'esthetic crown lengthening' may be carried out by performing gingivectomy and or osseous resection only on the facial aspect, for better esthetics.

Root exposure is often a common complication and intentional root canal or post surgical treatment with veneers or crowns may be required Functional crown lengthening: Whenever such a procedure is carried out in order to gain crown length for restorative purposes it is called 'functional crown lengthening'.

The gingiva and bone follow a definite pattern interproximally, facially and palatally.

Whenever the functional requirement needs more than 2mm of bone resection on the facial and palatal osseous crest a facial and palatal flap should be reflected and osseous resection is done all over including the inter-proximal region. This maintains the osseous contour around the tooth.

Esthetic Crown Lengthening.

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a)

Gingival margins of the right central incisor is at a lower level than the left central incisor.

b)

The dotted line indicates the oblique vertical incision without involving the interdental papilla.

c)

A full thickness flap is raised to gain access for osseous reduction; the blue dotted line indicates the amount of bone to be resected.

d)

The flap is sutured back into place.

Functional crown lengthening A and b : A labial and palatal view of a fractured central incisor; the blue dotted line indicates the incision to be followed for the raising of a full thickness flap.

C and d : A full thickness flap raised labially as well as palatally; here the blue dotted line indicates the amount of bone to be resected.

E and f : Osseous reduction carried out around the tooth using a round diamond bur.

G and h : The flap sutured back in place.

Excessive gingival display (gummy smile) A gingival display of more than 3mm in active or moderate smile may be termed "gummy". Excessive gingival display or gummy smile can be caused by any of three factors and because each is treated differently, a correct diagnosis is crucial.

The causes include: â&#x20AC;˘ Maxillary overgrowth â&#x20AC;˘ Tooth malposition

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• Delayed apical migration of the gingival margin or altered passive eruption Crown lengthening procedures can correct the latter two defects. However, in cases of excessive gingival display of more than 5mm a cephalometric analysis is recommended. Usually a surgical and orthodontic correction may be needed in these cases. The patient is well informed about the reason of this display. A short and thin upper lip may complicate the situation leading to difficulty in diagnosis.

Planning for gummy smile correction requires consideration of various aspects.

• Location of the cemento-enamel junction • Root length, form and position • Width of attached gingiva Technique for correction: The most basic of cosmetic crown lengthening procedures is carried out by removing excessive gingival tissue by gingivectomy. Preoperatively, the type of surgery needed for correction can be determined by probing through the connective tissue at the base of sulcus after anesthesia has been administered. A biologic width of more than 2mm beyond the base of the sulcus indicates that a simple gingivectomy procedure would suffice. Otherwise, bone must be resected to preserve normal bio-logic width.

In the absence of periodontal pockets healthy bone must be resected to have gingival margins properly located and bone margins at least 3mm apical to the level of the finish line of the tooth preparation. This takes into consideration the dimensions of the biologic width of the gingival unit.

Excessive gingival display during active smile.

Gingivectomy done in relation to the

203

Note the straight smile line, improper progressive abating and lack of balance in the smile.

maxillaryarch.

Flap sutured back after osseous reduction.

Veneer preparation performed after two months of post operative healing.

Postoperative view after veneer placement.

Note the correction of the overlap, creation of the gull wing effect and the esthetic gingival contours.

Postoperative view after 6 months. Note the convex smile line, good progressive abating and adequate periodontal health.

Root coverage procedures Gingival recession is characterized by the apical shift of the marginal gingiva from the crown of a tooth to the root, exposing the cemento-enamel junction. Root exposure can lead to hypersensitive teeth and esthetic concerns. The success of any surgical root coverage procedure is dictated by the presence of ample interproximal bone height and width. Periodontal surgical procedures have been developed in the past to treat muco-gingival deficiencies. The main aim of these procedures is to increase the amount of attached gingiva. For all root coverage procedures the root should be thoroughly planed and all local irritants removed. Pretreating or burnishing the roots with citric acid is recommended by some researchers.

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Rotational flaps: The lateral sliding pedicle flap is a predictable way of covering the recession. The availability of sufficient donor tissue contiguous to the recipient site limits the use of this technique. Color match is a major advantage of this technique.

Free gingival grafts: These are successfully used to cover recessions, especially when the graft is thick. This thick graft should be placed on vigorously prepared root surfaces with a retentive preparation on the recipient site with the use of mattress sutures to hold the graft in place. The greatest disadvantage of a free gingival graft is the shade difference, which is obvious. An alternative coronally repositioned flap with the already placed gingival graft, as a method to promote root coverage has also been described. This technique would need two separate surgical procedures but achieves the desired esthetic result.

Autogenous connective grafts: The conventional free autogenous graft technique describes a procedure where in a sub-epithelial connective tissue graft is placed over the root secondarily vascularized by the overlying split thickness flap. This technique not only increases the predictability of the graft by improving the blood supply but also provides a closer color match with the adjacent tissue. In addition the technique is more comfortable to the patient post opera-tively and allows multiple areas of recession to be covered by a single surgery.

Technique: At the donor site on the palatal mucosa, a flap is reflected to expose the underlying connective tissue which is excised and the overlying flap is sutured back in place. The recipient site is prepared to receive the graft. A partial thickness flap is raised. The donor tissue should extend on the neighboring periosteum to help in adequate circulation to donor tissue. The connective tissue graft is sutured to the underlying connective tissue at the recipient site. The overlying recipient flap is then sutured in place. A three month healing period is suggested to assess the healing result.

When the patient presents with severe facial alveolar bone loss or localized alveolar bone loss then the facial gingival tissues have to be restored through bone regeneration techniques.

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Gingival recession in relation to the maxillary anteriors.

Palatal donor site outlined in relation to the maxillary molars.

Recipient site prepared with a split thickness flap.

Diagrammatic representation of donor connective tissue graft obtained by raising the palatal flap and removing the underlying connective tissue from the site. Inset: Wedge of connective tissue.

Split thickness flap coronally placed over the connective tissue graft and sutured in place.

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If One week post operative.

Healing after 3 months.

Abnormal frenal attachments The maxillary frenum may cause esthetic problems especially in cases of gingival smiles. The frenum can also cause a pulling force on the gingival margin in some cases leading to gingival inflammation and progressive recession of gingiva. If the attachment of the frenum is very low or near the inter-dental papilla, excessive tissue may be seen in the center, usually associated with large diastema. Correction may be required prior to restorative procedures or orthodontics, for diastema closure.

A resection (frenectomy) or a repositioning (frenotomy) may be necessary. Whenever there is excessive pressure caused by the frenum then a frenectomy may be the best procedure, however when esthetics is the only factor then a frenotomy may be necessary to give the desired result.

In the active smile an abnormal bulbous frenum is seen between the central incisors.

Sutures in place after frenectomy.

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Enlarged maxillary frenum with a terminal bulbous end.

Post operative view after 1 month.

Excessive gingival pigmentation Skin tone, texture and color differ in races, and different regions. The color of the human gingiva also differs, usually pink with certain areas showing a diffuse pigmentation. Gingival pigmentation is due to the deposition of melanin pigments in the basal layer of the mucosa. In mammals it is brown, black or blue black depending on vascularity of the overlying tissue and epithelium. In man, the development of melanin requires the precursor, tyrosine.

Melanin pigmentation results from melanin granules, which are produced by melanoblasts. Whether or not clinical pigmentation is seen in the gingiva, melanin forming cells will be present. The degree of pigmentation depends on melanoblastic activity.

The saturation of these pigments causes an unesthetic dark gingival display. This looks even more unesthetic in people with fair skin and high lip lines.

Hyper-pigmentation of gingiva.

Criteria for patient selection â&#x20AC;˘ Skin shade not very dark toned, but gingiva is deeply pigmented.

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• Periodontal health, not compromised or is pretreated.

• Adequate thickness of the periodontal tissues If the patient has a skin color, which is dark and matches with the gingival shade then this procedure may not be advised. However in cases of major disparity of the skin and gingival shade a depigmentation procedure is recommended.

The depigmentation procedure is recommended after periodontal health is restored.

The thickness of the periodontal tissues helps to establish related thickness of the epithelium to determine the extent of surgical excision required. Pretreatment photographs help to mark pigmented areas on the model. The surgery can be performed under local anesthesia with the following techniques: • Gingivo-abrasion technique • Split thickness epithelial excision •

Combination technique which involves gingivo-abrasion and split thickness epi-

thelial excision Gingivo-abrasion technique: It is a very simple and effective technique. A medium grit football shaped diamond bur is used at high speeds on the epithelium to denude it.

Care should be taken not to abrade the periosteum. The pressure used with the diamond should be minimal and copious irrigation is recommended. Hand instruments with a circular cutting edge may also be used. A periodontal pack is then placed over the denuded epithelium. Usually in a week a new epithelium is formed .

Hyperpigmentation seen in localized areas.

A hand instrument with a circular cutting edge used over the pigmented area.

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Football shaped diamond bur is used to denude the epithelium in the gingival abrasion technique.

Postoperative view showing pink gingival tissue.

A diagrammatic representation of a circumferential incision involving the pigmented area.

A diagrammatic representation of a no.11 blade used to tease the superficial mucosal layer.

Split thickness epithelial excision technique: A split thickness island of epithelium is removed on the attached part of the mucosa.

A circumferential incision involving the entire pigmented area is made Tissue holding forceps are then used to raise the epithelium. A sharp no.11 blade is used to tease the epithelium away leaving the connective tissue intact, The epithelium excised may be in separate fragments. A periodontal pack is then placed and left for a week.

Combination technique: Incases where pigments are present very close to the marginal gingiva and where the gingival pattern has areas of depressions and elevations on the facial aspect, a combination technique is advised. Gingivo-abrasion is used near the marginal gingiva and areas where a split excision is difficult i.e. areas where contour of gingiva on facial surface is exaggerated. Care should betaken while denuding epithelium close to the marginal gingiva as traumatic loss of this critical tissue can lead to

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gingival asymmetry. A split thickness gingival excision is then performed to remove the remaining pigmented epithelium.

Intraoral view showing darkly pigmented attached and free gingival regions.

Two week postoperative view.

Most of the pigmented areas are eliminated by the combination of abrasion and excision.

A split thickness flap excision is carried out using a no.15 BP blade after carrying out gingivo-abrasion using a football diamond bur on the free gingival region.

A light cured periodontal pack is placed.

The main objective of the depigmentation surgery is to remove the epithelium leaving the connective tissue intact. The healing brings about a change in the color of the new epithelial tissue. This tissue looks pink and brings about a significant difference in the smile. However over a period of time pigments redeposit in the epithelium. It has been observed that the deposition of the pigments is faster after the abrasion technique as against the excision technique.

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Open interproximal spaces The interdental gingiva occupies the gingival embrasure which is the interproximal space beneath the area of tooth contact. The shape of the gingiva in a given interdental space depends on the contact point between the two adjacent teeth and the presence or absence of some degree of recession.

Open interproximal space may be caused due to diverging roots, abnormal clinical crown shape and absence of interproximal papilla. The first two can be corrected orthodontically and by the reshaping of clinical crown respectively, while the last is the most difficult to manage predictably. Preservation of papilla, therefore, is of utmost importance because currently there are no predictable methods to regenerate the interproximal papilla.

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ESTHETICS WITH ORTHODONTICS Restorative procedures employed to enhance esthetics produce great results but they also have some limitations in cases where tooth position needs to be influenced.

Orthodontics plays a vital role in such clinical situations where interproximal spaces need to be rearranged, opened or closed, proper angulations and inclinations need to be established, upper and lower arch forms need to be co-ordinated, bite to be opened and so on.

Establishing tooth proportions Abnormal positions of teeth in sagittal, vertical and transverse planes are the more obvious esthetic problems that confront orthodontists in day-to-day practice. Patients with missing teeth, unusual tooth morphology, undersized or oversized teeth, that are also associated with underlying restorative requirements pose esthetic challenges. If the discrepancies in the size of the teeth are over-looked during orthodontic treatment, the resulting dentition would lack dimensional proportionality and lead to poor esthetics. This is commonly seen in patients with peg-shaped maxillary lateral incisors or with interproximal decay in anterior teeth where resultant interdental spaces are closed without estimating the crown widths of the teeth to establish tooth proportions.

Crown width discrepancy Size of the teeth is one of the most important elements of anterior dental esthetics.

Orthodontists are often faced with disproportionate widths of anterior teeth during treatment. This tooth size discrepancy is commonly found in patients with peg-shaped lateral incisors. Even after getting the teeth perfectly aligned and the arch forms properly established with orthodontic treatment, the abnormal shape and smaller size of lateral incisor poses an esthetic problem.

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Proper distribution of spaces in the maxillary anterior region during the finishing stage of orthodontic treatment to restore normal widths of lateral incisors.

Peg-shaped lateral incisors are restored with ceramic veneers.

It is therefore imperative to restore the size of the lateral incisors after the completion of orthodontic treatment for good overall treatment result. During the finishing stage of orthodontic treatment, if excessive space exists in the anterior segment, it should be redistributed to restore the proper crown width. If insufficient space exists to restore these teeth, an adequate space should be gained which will permit the restoration of proper crown width. To determine the space required to restore the crown width, during the treatment planning stage, construction of a diagnostic wax-up is an important step to visualize the final result. After removal of the fixed orthodontic appliances, restorative phase should be immediately started and provisional restorations should be given be-forefinal restorations to avoid relapse.

During the finishing stage of orthodontic treatment sufficient space should be maintained to restore the normal width of peg-shaped lateral incisors. Maxillary pegshaped lateral incisors can be restored with ceramic veneers.

Proximal recontouring: Orthodontists often treat patients with larger anterior teeth.

When the widths of the anterior teeth do not follow the golden proportion, that is, when there is a discrepancy in the widths of the central incisor and the lateral incisor then the larger teeth should be recontoured to smaller size and the space thus created is effectively utilized by the orthodontist to resolve the discrepancy. This procedure is usually done before starting orthodontic treatment and care should be taken not to alter the morphology of the teeth and the contact points.

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Maxillary lateral incisors are larger in size and flared laterally.

Pencil marking on the teeth; the horizontal marking will determine the actual width of the tooth. The transitional line angles are marked to determine the boundaries of the face of the tooth.

Lateral incisors are reduced to smaller size without altering the morphology. This resulted in creation of interproximal spaces.

Orthodontic appliance in place and spaces utilized to align the incisors.

Proximal decay: It is common to observe proximal decay in anterior teeth especially when they are crowded and malaligned. This often leads to loss of proximal contacts and smaller teeth. If the transitional restorations are given without estimating the proposed widths of incisors prior to orthodontic treatment, the result would be well aligned teeth with disproportionate crown widths leading to poor esthetics.

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a) b) c) d)

Malaligned teeth with proximal decay Transitional restorations given prior to orthodontic treatment Fixed orthodontic appliance in place to align the teeth Final result showing well aligned teeth with disproportionate crown widths

Space regaining Adult orthodontic patients are more likely to have dentitions that have undergone some degree of mutilation over a period of time, which may require some alterations in treatment strategy. This is usually seen in patients with missing or premature loss of teeth where adjacent and opposing teeth get drifted into the edentulous space complicating already existing malocclusion. If this involves multiple teeth, it may lead to collapse of dental arches and significant esthetic and periodontal implications.

Therefore, a decision must be made that results in optimal esthetics, function and occlusion.

Space gaining for a single tooth restoration Loss of a permanent tooth in the dental arch, if not restored immediately, leads to a number of occlusal problems. Loss of a tooth in the posterior segment can lead to tipping and drifting of adjacent teeth, poor inter-proximal contacts, poorgingival contour, reduced inter-radicular bone, and supra-eruption of' unopposed teeth.

Segmental stainless steel wire with compressed Nitinol coil spring was placed between the first molar and the premolar. The maxillary first molar was moved distally 216

creating sufficient space for the pontic. After provisional restorations the final restorations were placed.

Loss of maxillary right second premolar which led to mesial tipping and mesio-palatal rotation of first molar. Unesthetic bulky prothesis is seen in the anterior region.

Maxillary right first molar has been moved distally to create a space for the pontic.

Final restoration in its place.

Replacement of missing laterals with implants

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Dental agenesis occurs quite frequently, especially of the maxillary lateral incisors, and it presents a true challenge for an esthetic solution. For a long time, many dentists had suggested an alternative treatment approach by moving the entire lateral segment mesially to place the cuspid in the lateral incisor position. However, this approach ends up with compromised results that do not fulfil the esthetic requirements of good orthodontic treatment, since the cuspid has a very different crown and root shape to that of the lateral incisor, as well as a darker shade. When, missing lateral incisor space is closed by moving the entire lateral segment mesially, lateral excursions are made using bicuspids, which have shorter, thinner roots, thus, functional requirements area also not fulfilled.

If fixed restoration is the treatment of choice, it requires reshaping neighboring teeth, with consequent removal of varying amounts of enamel, and eventual risk of gingival recession, caries etc.

The osseo-integrated implant is the most conservative and biological method, since the missing tooth can be replaced without damaging the neighboring teeth.

Maxillary lateral incisors are missing and the adjacent teeth have drifted into the space.

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Sufficient space created orthodontically to restore maxillary right lateral incisors.

If the use of implants is the part of treatment plan for the missing lateral incisors, it is necessary to decide the exact placement of implants, evaluate the smile line and gingival contour. When the lateral incisors are missing, there is usually no adequate space to restore them due to drifting of the adjacent teeth. In such cases, it is essential to gain adequate space with orthodontics for the placement of implant and crown restoration for good esthetic result. The exact amount of space created should be according to the proposed size of lateral incisors, which should be proportionate to the width of the central incisors. After opening up of sufficient space, acrylic teeth may be selected closer to the shade of the patient's teeth, bracketed and attached to the arch wire for esthetic purposes. Before the orthodontic appliances are removed it is important to evaluate radiographically the position of the roots of adjacent teeth. The roots of the central incisors and canines on either side in case of bilaterally missing laterals should be parallel to each other with adequate space between the roots for implant placement.

Before removal of orthodontic appliances, it is common to see adequate space for the prosthesis and inadequate space between the roots of the adjacent teeth for an implant.

This usually occurs due to tipping movement of adjacent teeth, which requires proper uprighting of the roots during the finishing stage of orthodontic treatment. The minimum space of 6.5mm between adjacent roots is required to place a standard implant of 3mm width.

Intra-oral periapical radiograph shows inadequate space between the roots of the adjacent teeth for placing an implant.

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Implant placed in the space created by orthodontic intervention between the central incisor and the cuspid.

Addressing functional requirements Functional efficiency of the stomatognathic system is one of the important goals of restorative treatment. It is therefore essential to define the occlusal scheme to be achieved post treatment right at the beginning of the treatment. Incisal guidance in protrusive excursions and canine guidance in lateral movements of the mandible are generally recognized as important parameters in present day concepts of occlusion. In certain clinical situations where there is anterior cross-bite or attrition of incisors with underlying restorative demands, it is essential to establish proper inclination of incisors for longevity of restoration and good function.

Impaired dento-facial esthetics and function due to absence of canines The position of canines in all three planes of space is very important from esthetic and functional point of view. The ectopic eruption and impaction of maxillary permanent canines is a frequently encountered clinical problem. The labial impaction of the maxillary canine is less frequent than palatal impaction and is often caused by insufficient arch length. As a result, the canine is often positioned high in the alveolar bone and erupts through the alveolar mucosa. It has been recommended that surgical procedures designed to expose impacted canines erupting through alveolar mucosa should simultaneously provide a band of attached gingiva to the exposed teeth.

Otherwise, improper soft tissue management may lead to muco-gingival recession and loss of alveolar bone. The canines also provide the main gliding inclines for lateral excursions of the mandible thereby providing the patient with a functional occlusion.

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Therefore, it is not only important to get healthy favorably positioned impacted teeth into occlusion but also to position them in such a way that they maintain the integrity of occlusion, provide good function and optimal esthetics.

Bilaterally impacted canines exposed surgically, and orthodontic attachment bonded to the crown.

Ligature wire passed through the attachment on the impacted canine and tied to the main arch wire. The flap is then sutured back into its place.

After the forced eruption of bilateral impacted canines; they are positioned normally into the arch.

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Discolored teeth In case of discolored anterior teeth, due to intrinsic stains, teeth are first properly aligned and positioned as per the treatment goals. However, during the finishing stage of orthodontic treatment, discolored teeth should be palatally positioned with respect to the adjacent teeth since it is difficult to mask these dark teeth in the final restoration without additional labial preparation. Additional preparation would leave a thin tooth structure creating a potential weak area at the neck of the tooth.

Ortho-perio-restorative perspective The diversity of mutilated and periodontally compromised patients has made it imperative for orthodontic therapy to be not only adjunctive, but also an integral part of the comprehensive treatment plan. An integrated orthodontic, periodontal and restorative treatment is useful in wide variety of patients for improved occlusal relationships of teeth, propergingivalarchitectureand esthetic, biologically sound restorations.

a, b) Labial and occlusal views of discolored central incisors and crowded anterior teeth, c) Teeth are aligned with slight lingual positioning of central incisors. d) Esthetic restoration on central incisors.

Abnormal gingival architecture

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Color, contour and the health of the gingival tissues provide the framework and backdrop for the esthetic smile. Even if the case is well finished with orthodontic treatment, abnormality of the gingiva either in the form of loss of papilla, asymmetrical pattern and excessive display leads to a poor result. It is therefore essential to have proper gingival architecture and display to achieve a maximum esthetic result. During the process of eruption the whole periodontal apparatus is carried with the erupting tooth. When there is asymmetric eruption of the teeth it will also result in discrepancies in heights of the underlying crestal bone. This, in turn, results into asymmetries in gingival heights (gingival zenith) from one side of the arch to the other. This type of a clinical situation can be managed orthodontically by intrusion or extrusion of teeth.

Forced eruption Forced eruption is one of the adjunctive orthodontic treatment procedures where controlled vertical extrusion of a tooth is carried out to improve the prognosis of other treatment procedures. When performed, it allows the placement of crown margins on sound tooth structure, improves gingival contour thereby producing better esthetics.

During the forced eruption, as the tooth moves occlusally, attached gingiva (periodontal apparatus) follows the cemento-enamel junction. After the completion of forced eruption, the tooth should be stabilized in its new position for a period of 3 to 6 weeks. This will allow proper reorganization of the periodontal fibers and remodeling of the bone preventing relapse.

Gingival heights of the left central and lateral incisors were at a higher level than that of right central and lateral incisors. Orthodontic brackets were bonded to the teeth for supra-eruption of incisors (forced eruption) more so on the left central and lateral incisors This was to move the finishing margins of the restorations incisally. More extrusive force on the left central and lateral incisors due to cervical positioning of brackets on these teeth would move the gingival margins incisally.

After differential forced eruption of incisors, arch wire was changed and left passive into the slots of the brackets. There was still slight discrepancy in the gingival heights of left and right incisors. Therefore, the crown lengthening procedure was planned on

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the right central and lateral incisors to resolve the residual discrepancy. And the final result was achieved.

Forced eruption of maxillary left central incisor.

After the differential forced eruption of incisors; the crown extension procedure was planned on maxillary right central and lateral incisors to resolve the residual discrepancy

Faulty maxillary anterior restoration violating the biologic width. Note the discrepancy in the heights of gingival margins. The incisal edges of the central and lateral incisors are too far apically placed as compared to the canine.

Final restoration on the maxillary incisors with symmetrical gingival heights and physiologic positioning of finishing margins.

When a tooth is badly decayed, to the extent that the whole crown is broken down and only the root is remaining, the future line of treatment would depend upon whether the root can be preserved or not. If the root length is sufficient enough to support the prosthesis, it would be worth the effort to preserve the root. Preservation of the root involves complete removal of decay and locating the margins of the final restoration respecting the biologic width. Following treatment options can be considered.

• Crown lengthening procedures • Orthodontic forced eruption • Corrective periodontal surgery • Supra-crestal fibrotomy 224

â&#x20AC;˘ Combination of the above two procedures

Controlled extrusion of the fractured root carried out with bonded attachment in the root canal.

If the root length is not adequate to support the prosthesis, it can be extracted and other treatment options such as implants or other prosthesis could be considered. In case of adolescents where traumatic crown fractures are encountered, the roots may have to be saved not only to give interim restorations but to preserve the bone and allow root formation to facilitate the proper growth of the jaw before such time that a final solution could besought.

To summarize this, forced eruption with crown extension procedure enables the dentist to achieve symmetrical gingival heights, identical crown lengths, healthy gums and great esthetics.

.

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ESTHETICS WITH IMPLANTS The replacement of missing teeth to restore lost function and esthetics has posed a challenge from a very long time. Various treatment options have been successfully employed to provide sound replacements for lost natural teeth using available support from various hard and soft tissues of the mouth, either singly or in combination.

The wide array of implant systems available with a good track record has enabled the dentist to choose from an extensive range of stable implants for a particular edentulous region. With the ever-increasing emphasis on the esthetic aspect of the restorations, especially in the anterior region, it is imperative that this treatment option be offered beginning with the end in mind.

• Pre-implant esthetic considerations • Factors forfavorable implant placement • Soft tissue and osseous augmentation for the edentulous ridge • Provisional restorations and papillary reconstruction

Pre-implant esthetic consideration Evaluation of general risk factors is the be-ginning of any implant procedure.

General risk factors covers those that present general pathoses, such as diabetes, anemia and habits such as smoking and bruxing that pose a risk in osseo-integration.

In cases of anterior implants in the esthetic zone. certain specific esthetic criteria have to be considered. When esthetics is the prime reason for seeking implant prosthetic treatment, the patient's upper lip line will be of extreme importance for the planning of the definitive superstructure. In patients with a high lip line or requiring upper lip support from the prosthesis a removable over-denture will more likely fulfill the demands of function and

esthetics

than an implant-borne bridge construction.

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The single tooth anterior implant situation is of great concern as the esthetic requirements and expectations have to be properly balanced keeping in mind anticipated post-surgical results. The dentist should analyze anterior single tooth implant situation considering the adjacent teeth, contra-lateral tooth, probable emergence profile and presence or absence of interdental papilla whenever the active smile exposes enough of gingival tissues.

There are many limitations and contraindications specific to the maxillary single tooth implant apart from the routine contraindications associated with implant therapy. The common causes of a missing maxillary tooth is traumatic loss, root fracture, agenesis and periodontal disease. All these leave some deficiency in the facial bone over the root of the missing tooth. Majority of the cases of maxillary single tooth implant in patients with high upper lip line require bone grafting for ideal esthetics while in some cases bone grafting would be necessary to provide adequate healthy peri-implant soft tissue to maintain optimal hygiene in the cervical region.

The congenitally missing tooth requires at least 6mm of bone between the roots of adjacent teeth apart from sufficient labio-palatal thickness to accommodate the implant dimension, proper soft tissue contour and interdental papilla. In cases of periodontal disease the adjacent teeth should be stable to allow proper dissipation of forces in all anterior teeth and the implant prosthesis as excessive forces will have to be borne by the implant which could be detrimental to its success. The inter-occlusal space should also be assessed carefully. In cases of diminished vertical space implants may be best avoided unless other measures to correct the occlusion are considered.

Apart from the inadvertent deficiencies in the facial bone associated with various clinical situations, the soft tissue form also plays a major role in the esthetic outcome of single tooth implants.

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There are two basic human gingival types i.e. thick flat type and thin scalloped type. Although minor variations are seen in some cases, most of the human perio-types fall in the above mentioned categories.

Thick, Flat type

Clinical photograph showing thick and flat type of gingiva. The teeth are more bulbous and squarish

• •

X-ray of the same patient showing that the roots are broad and taper gradually

Soft tissue curtain is thick, short, dense and fibrotic.

Normal rise and fall of the gingiva and bone with less disparity between the direct facial and interproximal gingiva.

•

Tooth form is more bulbous or squarish and roots are broad and taper gradually.

•

The contact areas begin more apically and are usually broad incisogingivally and facio-lingually.

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Thin, Scalloped type

Clinical photograph showing thin and scalloped type of gingiva. The teeth are more narrow and triangular

X-ray of the same patient showing that the roots of the teeth are more tapering.

•

Soft tissue curtain is thin, long, delicate and friable.

•

Normal rise and fall in gingiva and bone with a disparity between direct facial and interproximal gingiva.

•

Tooth form is usually more triangular and roots are more tapered.

•

The contact areas are more incisal and smaller

inciso-gingivally

and

facio-lingually.

In all cases of inadequate tissue quantity, the disparity between the facial and interproximal gingiva and a more triangular crown form pose difficulties for optimum esthetic results. Masking interproximal spaces is thus more of a problem in thin scalloped gingiva than the thick flat type.

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In thick, flat type of gingiva, interproximal papillae remain intact after extraction thus easy to restore esthetically

In thin, scalloped type of gingiva, extraction results in loss of interproximal papillae leading to black triangular which are difficult to mask

Esthetic Risk Factors

Proceed

Caution

Alert

Esthetic demand

Reasonable

High

Unrealistic

Upper lip line

Dental

Gingival

Gummy

Vertical bone resorption Absent

Considerable

Significant

Gingival architecture

Thick fibrous

Thin fragile

Very thin with cleft

Mucosal thickness

4.5 mm

3 mm

Less than 3mm

Vestibular concavity

Absent

Present

Exaggerated

Very large or Mesiodistal dimension of Adequate to insert Larger than the smaller than tooth to the edentulous area implant tooth to be replaced be replaced

Factors for favorable implant placement Successful implant placement must be accomplished in three planes, namely mesiodistal, apico-coronal and labio-lingual.

Implant-bone dimensions: By knowing the dimension of the implant and related components, the surgeon can balance the space required to insert the fixture and place the desired restoration. However, the physiologic limits within which the implant can be placed are governed by the following:

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â&#x20AC;˘ The space between implant and periodontal ligament of the adjacent tooth should be 1 mm. â&#x20AC;˘ The average width of periodontal ligament is 0.25mm.

These natural periodontal components will require a space of 1.25mm on either side of the implant. Thus, mesio-distally the implant diameter is added to this minimum space required. However, the facio-lingual requirement may be slightly less as the periodontal ligament need not be considered. Thus, for a 3.5mm implant placed in the anterior region a minimum of 6mm of space mesio-distally has to exist to accommodate all related components. Ideally, the ridge should be 5-6mm wide labio lingually, to allow at least 1 mm of the cortical bone labially and lingually. However, to impart esthetics in the interdental papilla region, the distance between an implant and natural teeth is kept 2mm.

The distance between the center of two adjacent implants should be equal to the sum of radius of both the implants plus-2mm.

The interproximal embrasure is an important element to be considered and thus the interdental papilla should be preserved whenever possible. Whenever the mesio-distal diameter is sufficient then the flap is raised without raising the papilla at the surgery stage.

Incision made without involving interdental papilla.

On an average the implant fixture head should be placed far enough apical to the cemento-enamel junction of the adjacent natural teeth to allow sufficient

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room for the crown to emerge from a round implant to a triangular emergence profile.

Implant placed apical to the cementoenamel junction of adjacent teeth.

The implant should be 3mm apical to the gingival margins of the adjacent teeth. The cemento-enamel junction of the adjacent teeth can be taken as a reference provided the cemento-enamel junction and the gingival margins coincide. Sometimes certain procedures may be needed in the adjacent teeth to give the desired result.

Labio-lingual orientation of the implants helps to achieve desired emergence profile. Placing the implant slightly palatally helps the dentist to build up a proper emergence profile to the crown.

Illustration showing proper emergence profile.

Tooth extraction leads to loss of bone, both, in the apical and palatal direction.

A labial concavity is thus created. To avoid this labial concavity during surgery the implants have 232

to be fixed more palatally. For every 1 mm of palatal position of the implant, the implant has to be placed 1mm apical to allow a proper emergence profile for the restoration.

A round implant and crown emerging into a triangular form.

However, in cases where the implant is placed too palatally, the crown would have an unfavorable shape near the gingiva leading to persistent inflammation of the gingiva and abnormal forces.

Illustration showing an emergence profile which is difficult for maintenance

In cases of vertical resorption of bone the implant may have to be placed too apically making the pontic too long compared to its contra-lateral tooth.

To obtain satisfactory peri-implant gingival morphology, tissue volume should be 20-25% more than the estimated need to allow adaptation of gingiva to the prosthetic reconstruction. It will help solve certain esthetic problems that involve the emergence profile. Wider diameter implant will ease the transition

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of the implant head to the artificial crown as it emerges from its soft tissue housing. The wider diameter implants will not be required to be placed far apical to the cemento-enamel junction of the adjacent tooth. Immediate implants help to preserve the hard and soft tissues, and maintain the emergence profile as in natural teeth.

Fractured carious maxillary left premolar in the esthetic zone which needs replacement with implant

The crestal bone is located apically and the mucosal thickness is assessed to be around 3m.

Post extraction socket showing the contour of the bone.

A wide implant is placed at the crest of the bone. The placement at the crest will allow a good emergence profile to the final restoration

Abutment selection â&#x20AC;˘ In anterior situations, abutment selection will depend on factors like the angulation of the implant, the quality and quantity of the soft tissue at the prosthesis interface of the implant and whether a metal-free restoration is planned on these implants. When the maxillary anterior implant is placed labially then a cemented prosthesis may be mandatory. In palatally placed im-

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plant a screw retained prosthesis may be given. In cases of extreme angulations custom-made abutments may be required.

• The height of the soft tissue dictates the length available for the emergence profile. Soft tissue heights of less than 2mm create an esthetic challenge, while heights of more than 4mm present long term soft tissue hygiene maintenance problems.

•

The polished collar of the abutment can be trimmed to suit the gingival

contour to create an esthetic emergence profile.

•

A transitional abutment available in certain systems can be used to shape

and maintain soft tissue contour during the healing phase.

A over retained deciduous tooth leaving a space of 5.5mm mesio-distally

Implant placed 2mm apical to the CEJ of the contra lateral incisor to create an esthetic gingival pattern as well as an ideal emergence profile.

Thin gingiva around the implant with lack of interdental papilla poses an esthetic challenge

The contact area of the final restoration is long and placed cervically to balance the missing interdental papillary regeneration giving a good esthetic result.

• Abutments of tooth colored materials are used to create ultimate esthetic prosthesis. These are especially important for cases of thin scalloped gingiva treated with metal-free prosthetic restorations.

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Augmentation One of the biggest challenges in a single tooth implant in the esthetic zone is the creation of a harmonious gingival contour around the restoration. Soft or hard tissue deficiencies of the edentulous space are the most obstacles

in

common

achieving gingival contour around the proposed restorations.

When the alveolar ridge dimensions are not adequate (width less than 5mm and height less than 10 mm) for the correct placement of the implant then augmentation of the alveolar ridge is needed. Ridge augmentation techniques may involve either osseous or soft tissue reconstruction or a combination of both procedures. These methods have been adapted for use in the treatment of patients with implants.

The onlay graft technique is effective for solving moderate to severe vertical defects but often does not achieve a close color match of graft tissue to the adjacent gingiva. A more popular soft tissue grafting technique uses autogenous sub-epithelial connective tissue harvested from the palate or the maxillary tuberosity. In the treatment of either horizontal or moderate vertical defects the connective tissue is placed under a labially reflected split thickness flap. In patients with only a horizontal defect, a sub-epithelial pouch can be prepared at the site receiving the autogenous connective tissue graft. In certain defects a second stage surgery is recommended to get the desired dimension of the ridge.

Some soft tissue augmentation techniques offer the advantage of overcontouring of the defect. Recontouring during the prosthetic phase of treatment to create gingival symmetry with the adjacent teeth can easily be accomplished.

The osseous augmentation procedures can be performed for pre-implant site development and during implant placement. If primary stability or appropriate positioning cannot be achieved, ridge augmentation is recommended before implantation.

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Preoperative radiograph showing an infected first premolar root piece

The extraction socket showing a buccal defect of the bone.

Inset: Root piece shows a large periapical lesion

The socket filled with bone graft which is densely condensed over which the resorbable membrane is covered

Postoperative picture one year after augmentation surgery.

Postoperative radiograph one year after augmentation surgery

The buccal defect is completely filled and the implant can be placed safely

Implant is placed leaving sufficient space on either side to allow soft tissue adaptation which will help to create esthetic interdental contours

Radiograph showing six months post surgical bone healing.

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Six months postoperative view showing healthy gingival tissue around the implant supported restoration

The use of autogenous bone graft is preferred because of its good osteogenic properties. Various extraoral donor sites have been used but the iliac crest is the most common site to harvest large amounts of autogenous bone. Local bone defects in the anterior maxilla usually need only a small graft for which donor sites can be found within the oral cavity. Common intraoral donors sites include the mandibular symphysis and the maxillary tuberosity. Intraorally harvested grafts show better results than iliac crest and rib grafts. Resorption is most pronounced after use of maxillary tuberosity grafts and negligible in case of mandibular grafts.

When threads of a stable implant are exposed because of a small bone defect in the area or some other reason, then a membrane may be used to act as an occlusive barrier that impedes the entry of rapidly proliferating gingival epithelial cells into the osseous defect, while osteo-competent cells, which migrate at a slower rate, gradually fill the defect with bone. The membrane may or may not be resorbable. The advantage of using a resorbable membrane is the elimination of a subsequent surgery to remove it. The non-resorbable membranes are used for bigger defects which need more time to heal. In orderto put a membrane, a full thickness flap is raised and the membrane is carefully placed so that it does not touch the adjacent teeth or the papilla but extends 2-3mm overthe defect. The defect is filled with bone chips and is condensed well so that no empty spaces are left under the membrane. The membrane is then pressed over the bone and the flap is sutured in two layers.

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Preoperative photograph showing damaged central incisors

The infection has lead to the loss of the labial bone which will cause a discrepancy in the implant placement

Post extraction socket is thoroughly cleaned and site is prepared for immediate implant

Two screw implant placed in sockets more palatally at the same level

Bone augmentation materials is densely packed around the implant

A resorbable membrane is placed over the surgical site and compressed to leave no space between the membrane and the graft material.

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Site is well sutured to allow healing. Care should be taken that the membrane is not exposed.

The implants in their respective position in the bone showing adequate healing. The graft material can also be seen around the neck of the implant

Papillary reconstruction and immediate provisional restorations The reconstruction of missing papillae is still unpredictable. Some surgical techniques are reported, but only a non-surgical method i.e. by modifying the interdental space through temporary crowns seems to be effective in some specific situations.

If the gingival contour does not permit creating the proper gingival architecture at the time of the prosthetic phase, a surgery is performed. An incision is made from the palatal angle of each of the adjacent tooth, a release incision is then made in the midline to the height of the facial gingival contour.

When interdental anatomy is not adequate, incision is made on palatal aspect of the ridge. Flap is raised and the healing cap inserted into implant body.

The cover screw of the implant is removed and replaced by a healing cap of 2mm height. Hydroxyapatite is densely packed around the healing cap and the flap is sutured back allowing the palatal portion to heal by proliferation of soft tissue. After 3-4 weeks gingivoplasty is performed to remove the healing screw and a suitable abutment is placed. An interdental papilla may be reconstructed in an edentulous region using this procedure.

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When the distance between the crest of bone and the contact point is less or equal to 5mm, then a papilla exists. This accommodates for the periodontal infrastructure in this region. If we increase the distance more than 5mm no papillae will be present. Papillae regeneration is related to the contact points of adjacent teeth. So, if the implant crown does not have a good contact with the adjacent teeth then the interdental papilla will be lost. The objective is to preserve or develop interproximal peaks of bone at stage 1 (implant placement) in order to optimally support the papillae.

Prosthetic factors required for papilla growth can be explained as follows: â&#x20AC;˘ At second phase, the prosthetic restoration should exert lateral pressure on the soft tissues in the interproximal zone as soon as possible. This gentle pressure is the key to reformation of the gingival peaks. Proceeding with the impression immediately after uncovering and temporizing as soon as possible during the inflammatory period is advisable as the gingiva has the best dynamic potential for guidance.

Radiograph showing implant placed in the first molar region

Excellent healing is seen in the peri-implant gingival tissue. Note the interproximal papilla

To create natural interdental papillae, an interim restoration is placed to exert lateral pressure on the interproximal soft tissue

The emergence profile of the provisional restoration is cautiously recreated using the dimensions of the contra-lateral teeth as prosthetic references. This

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emergence profile is of critical importance. If it is too narrow, there will be no lateral pressure, no support for the gingiva and the interdental papillae will diminish. If it is too wide the papillae will be vertically compressed, oral hygiene will be difficult and the papillae will collapse. â&#x20AC;˘ The proximal surface is the third factor. The contact area of the crown should be close enough to the gingival embrasure, with its apical limit located less than 5mm from the osseous crest. Opening large embrasures in order to facilitate oral hygiene is contraindicated if papillary growth is desired.

Immediate provisional restorations after surgery is a major challenge to the dentist. The use of transitional implants thus becomes mandatory in some cases. Transitional implants are placed between multiple endosseous implants, to act as intermediate fixtures on which the prosthesis can be anchored immediately after surgery. However, the single tooth implant is a different situation to tackle as transitional implant cannot be placed. A bonded prosthesis may be used to restore the missing tooth in such cases. The immediate provisional should match the contour of the final restoration, but it is advisable to allow excess tissue adaptation around this provisional as additional soft tissue is always preferred during the prosthetic phase. To achieve this, the immediate provisional is kept slightly shorter than the aimed final restoration.

The patient is instructed to follow proper maintenance protocols to keep the tissue healthy.

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REVIEW OF LITERATURE Simon J. (2004) Many dental patients are unhappy with their smile but believe a beautiful smile is outside their budget. The first step is to listen to the patient in order to understand what his or her primary concerns are. The second step is to examine carefully and analyze the case to develop a treatment plan that will fulfill as much as possible of the patient's desires within the context of his or her constraints (financial or otherwise). Also, remember that dentistry doesn't end when the last veneer is placed or the last bill is paid. The final step is to maintain a strong relationship with your patients to ensure good oral hygiene and restorations that are as long-lasting as they are beautiful.

Neves FD, Mendonca G, Fernandes Neto AJ. (2004) The lip line and lip support influence esthetics and selection of implant-supported prosthetic designs for maxillary edentulous patients. This article describes a procedure to analyze the influence of lip line and lip support on the esthetics of an existing maxillary complete denture, revealing potential limitations when planning a fixed implant-supported prosthesis.

Ibbetson R. (2004) Many dental practitioners do not use adhesive bridges because of concerns over high failure rates. Techniques for these restorations should be based on the fundamental principles of bridge design which require rigid, accurately fitting frameworks and careful control of the occlusion. The abutments generally require little if any tooth preparation. Greater security will result from more extensive coverage of abutment teeth: the routine use of relative axial tooth movement is a predictable method for creating the space that this approach requires.

Flores-Mir C, Silva E, Barriga MI, Lagravere MO. (2004) To compare the aesthetic perception of different anterior visible occlusions in different facial and dental views (frontal view, lower facial third view and dental view) by lay persons.

The different views were rated by 91 randomly selected adult lay persons. Visual Analogue Scale (VAS) ratings of aesthetic perception of the views. Anterior visible occlusion, photographed subject and view (p<0.001) had a significant effect on the aesthetic ratings. Also gender (p=0.001) and the interaction between gender and level of education (p=0.046) had a significant effect over the aesthetic rating. A lay panel perceived that the aesthetic impact of the visible anterior occlusion was greater in a

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dental view compared with a full facial view. The anterior visible occlusion, photographed subject, view type are factors, which influence the aesthetic perception of smiles. In addition, gender and level of education had an influence.

Olsson KG, Furst B, Andersson B, Carlsson GE. (2003) The purpose of this study was to evaluate the long-term outcome of In-Ceram Alumina fixed partial dentures (FPD) performed in a general dental practice from 1992 to 1996. The study was conducted as a retrospective assessment of up to 9 years of patient records and a clinical follow-up examination of patients treated with In-Ceram Alumina FPDs. In 37 patients, 42 FPDs had been inserted during the selected period. After randomized selection, 16 patients with 18 FPDs were examined clinically. The most common restorations comprised two and three units. Cantilever extensions were present on 64% of the FPDs. Sixty-two percent of the FPDs extended into the posterior region.

The mean time in function for the 42 FPDs was 76 months (range 2 to 110 months), with 86% being followed for > 5 years. No adverse effects to either periodontal or pulpal tissues were recorded. The technical quality was very good, and patient satisfaction very high. Five FPDs fractured during the observation period, resulting in a total failure rate of 12%. Two of these FPDs fractured as a consequence of external trauma. Excluding these, the total survival rate during the observation period was 93%. Cumulative survival rate according to life table analysis was 93% after 5 years and 83% after 10 years. The results suggest that the In-Ceram Alumina short-span FPD is a viable prosthetic alternative.

Frindel F. (2003) The present study aims at establishing elements for diagnosis and construction of a harmonious, balanced, desirable and durably young smile. Once the importance of a harmonious smile in today's society has been studied, smile is analyzed under two aspects. One considers it in its own unitary structure, the other in its living immediate environment: the face. Sixteen key rules have been defined to characterize and analyze it. Those various "keys of smile" will enable the practitioner to construct it in positioning the maxillary teeth in a facial balance, thus meeting the criteria of esthetics and appeal so much wanted by our patients. Taking into account the criterion of general aging of the face, the smiles thus realized will remain young for a longer period of time. Three principles of analysis have been used to achieve this task: the observation in "dynamic" situation (as opposed to a "static" frozen study),

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the reference to particular measurements for each case (as opposed to measurements refering to statistics tables), and the evaluation of the interlabial space at rest of the case considered. This leads to the definition of the measurement of the "golden section dynamic smile" (G.S.D.S.) and a reminder of the measurement of "the constant of ideal smile" (C.I.S.). Adorned with such smiles, our patients will benefit from a real feeling of well-being which they will communicate to their circle of friends and acquaintances for their greatest delight.

Naylor CK. (2002) It is sometimes difficult to identify esthetic problems let alone pre-visualize an esthetic end-result. The Esthetic Grid Analysis is a system for analyzing the basic problems that detract from the concept of an attractive smile. A photograph is taken of the anterior teeth with the lips retracted. The upper and lower frame of the photograph is aligned parallel with the interpupillary line, assuming that the interpupillary line is parallel with the horizon. Where this is not the case, the vertical margins of the photograph are aligned parallel with the facial midline.

Through orienting the photograph to the facial guidelines and incorporating the idealized positions of the incisal plane, highest lipline, midline axis, and proportionate contact areas, a grid is formed. The grid built from these components provides a method of demonstrating deviations from an esthetic arrangement of anterior teeth.

Integrating facial guidelines with the dental composition using a grid highlights deviations from the ideal. It thereby assists in the treatment planning process by communicating esthetic problems to the patient, laboratory personnel, and other specialists.

Gillet D, Miquel JL, Jeannel A. (2002) The aim of this study was to evaluate the importance of the dental aesthetic for the patients, the dental surgeon and the dental teachers by the study of the consultation reason, the complaints, the post-university congress program, the practical program of the dental students and the programs of the IADR congress. It appears that in odontology, patients ask strongly for aesthetic care, in consultation and litigation. The content of congress and professional literature shows that dental surgeons answer to that request. Only the practical teaching was a bit less but it was recently modify. The research workers are also very interesting for aesthetic care.

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Rosenstiel SF, Ward DH, Rashid RG. (2000) This study aimed to determine dentists' esthetic preferences of the maxillary anterior teeth as influenced by different proportions. The goal was to link choices to demographic data as to the experience, gender, and training of the dentist. Computer-manipulated images of the 6 maxillary anterior teeth were generated from a single image and assigned to 5 tooth-height groups (very short, short, normal height, tall, and very tall). For each group, 4 images were generated by manipulating the relative proportion of the central incisors, lateral incisors, and canines according to the proportions 62% (or "golden proportion"), 70%, 80%, and "normal" or not further altered. The images were randomly ordered on a web page that contained a form asking for demographic data and fields asking for a ranking of the images. Dentists were asked via e-mail to visit the web page and complete the survey. The responses were tabulated and analyzed with repeated measures logistic regression with the alpha at 0.05. A subset of North American respondents was chosen for further analysis. A total of 549 valid responses were received and analyzed from dentists in 38 countries. There were statistically significant differences in all groups for the variables of proportion, group (tooth height), and their interaction. The 80% proportion was judged best for the Very Short and Short groups. Three of the choices were almost equally picked for the Normal Height and Tall groups, and the golden proportion was judged best for the Very Tall group. The variables of year of graduation, gender, professional activity, generalist or specialist, or number of patients were not significantly correlated with the choices for the North American respondents. Dentists preferred the 80 percent proportion when viewing short or very short teeth and the golden proportion when viewing very tall teeth. Golden proportion was worst for normal height or shorter teeth and the 80% proportion for tall or very tall teeth. They picked no clear-cut best for normal height or tall teeth, and their choices could not be predicted based on gender, specialist training, experience, or patient load.

Snow SR. (1999) With increasing application of cosmetic dental treatment comes the need for a greater understanding of esthetic principles. Scientific analysis of beautiful smiles has revealed repeatable, objective principles that can be systematically applied to evaluate and improve dental esthetics in predictable ways. Symmetry across the midline, anterior or central dominance, and regressive proportion are three composition elements required to create utility and esthetics in a smile. The Golden

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Proportion has been suggested as one possible mathematic analysis tool for assessing dominance and proportion in the frontal view of the arrangement of maxillary teeth. It has proven to be controversial in developing esthetically beautiful smiles and cumbersome for evaluating symmetry. This article considers a bilateral analysis of apparent individual tooth width as a percentage of the total apparent width of the anterior segment and proposes the concept of the Golden Percentage as a more useful application in diagnosing and developing symmetry, dominance, and proportion for esthetically pleasing smiles.

Magne P, Magne M, Belser U. (1999) With the evolution of adhesive dentistry and the increasing use of porcelain veneers, single-unit crowns generally are restricted to the replacement of pre-existing full-coverage crowns and the restoration of nonvital and/or severely damaged teeth. Porcelain-fused-to-metal restorations are still widely used to generate single-unit crowns and fixed partial dentures. Collarless metalceramic restorations represent the most successful evolution among efforts to meet maximum esthetic requirements using porcelain-fused-to-metal restorations. Extended metal frameworks and opaque aluminous ceramic cores are associated with unpleasant optical effects in the soft tissues surrounding such restorations. This problem is particularly evident in the presence of the upper lip, which can generate an "umbrella effect" characterized by gray marginal gingivae and dark interdental papillae. Based on the concept of the biologic width, a systematic approach is proposed for the elaboration of an "esthetic width," including: 1) positioning of preparation margins; 2) reduction of the metal framework; and (c) appropriate marginal design of porcelain-fused-to-metal restorations. Strategic features of pontics and a specific interdental design are suggested to compensate for deficient anatomical features of the soft tissue and the edentulous ridge.

Smukler H, Chaibi M. (1997) When the clinical crowns of teeth are dimensionally inadequate, esthetically and biologically acceptable restoration of these dental units is difficult. Often an acceptable restoration cannot be accomplished without first surgically increasing the length of the existing clinical crowns; therefore, successful management requires an understanding of both the dental and periodontal parameters of treatment. This report provides further insight into this interdependence by examining the effects of tooth form on the periodontal morphology and surgical

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treatment, while relating them to requirements for esthetically and biologically acceptable full-coverage dental restorations. This report also explains the role that restoration margin location and emergence profile play in the maintenance of periodontal and dental symbiosis.

Burckett PJ, Christensen LC. (1988) The results of this study indicate that it is difficult to correctly age and sex by using anterior teeth as a guide. The difficulty in estimating age and sex in dental patients is that they do not always fall in set patterns.

Teeth do tend to darken with age but, this is not always true. Older dentitions sometimes show minimal wear and some younger dentitions can show moderate to excessive wear. The position of the maxillary lateral incisors does not always enhance male and female characteristics. Perhaps the best method to select denture teeth for a patient is to place more consideration on previous dentures and photographs and less on the age and sex of the patient.

MacArthur DR. (1987) 1) For all samples, men had larger central incisors than women. 2) The mean mesio-distal diameter for permanent maxillary central incisors was similar for both the orthodontic and the mixed dentition samples. 3) Mesio-distal and incisal tooth wear results in narrower central incisors in older age groups. 4) The size of artificial central incisors is generally appropriate for the senior population.

McArthur DR. (1985) The average width of a natural maxillary central incisor is 8.92 mm. This value is determined from the results of three studies of natural dentitions. The average width of a mandibular central incisor is 5.5 mm. The average ratio produced by dividing the average maxillary central incisor width by the average mandibular incisor width is 1.62. The factor of 1.5 times the width of a mandibular central incisor produces a maxillary central incisor width that is too narrow. The width of a mandibular central incisor plus half the width of the mandibular lateral incisor also produces a maxillary central incisor width that is too narrow. There may be a tendency to undersize the maxillary prosthetic dentition. The ratio of 1.62 can be used to select the appropriate width for a missing maxillary central incisor when given the width of the mandibular central incisor. This ratio of 1.62 is also valuable to verify the dimension of a selected artificial maxillary central incisor when the patient complains that the tooth is too large. If substitutions or adjustments are made in the

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mold, the desired canine-to-canine measurement produced by the ratio range of 1.3 to 1.38 reported in Parts I and II of this study should be maintained.

Matthews TG. (1978) The anatomy of smile is an integral part of dentistry. Its understanding involves close scrutiny of all elements of the oral region. It is not enough to establish the size of teeth based on the high and low lip lines, size of the mouth, and a shade to blend with the age and complexion. To create a harmonious smile the dentist must maintain or create the normal curvature of lips, proper exposure of the red zone of the lips, an undistorted philtrum, and undisturbed naso labial grooves. These entities, maintained in harmony with the exposed teeth, constitute the anatomy of a smile.

Levin EI. (1978) A system of esthetic predictions is described that has been used since antiquity. The naturalness of the system is emphasized by showing examples from nature and how artists and designers use it. The application of this system to dental esthetics is facilitated by the description and inclusion of a dental grid for the anterior esthetic segment.

Lombardi RE. (1977) Factors mediating against excellence in dental esthetics have been classified and enumerated in this article. A formula for producing unaesthetic prostheses can be hypothesized as follows: Educational de-emphasis + Lack of research + Technical orientation + Technical tradition + Delegation (abdication) + Poor economics + Fatigue + Poor office design + Convention + Conditioning + Schemata leads to POOR DENTAL ESTHETICS. It is postulated that a formula for excellent dental esthetics can be produced by reversing these factors: Altered schemata + Deconditioning + Altered convention + adequate office design + Elimination of fatigue + Favorable economics + Personal participation + Research + Educational emphasis leads to Esthetic Excellence.

Lombardi R. (1973) A real need for a very detailed, almost histologic approach to dental esthetics exists. Indeed, the perspective principles may be regarded as the cellular elements of which the tissue of denture esthetics is composed. As familarity with the principles increases, so does proficiency in their application. With experience, the basic shape and characteristics of the dental tooth arrangement can be visualised even before a single tooth is placed in wax. All that remains is a detailed

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examination at try-in to look for minor perspective conflicts, and this too becomes less of a task with the training of the eye to really see.

Weinberg LA. (1960) This article emphasizes the dynamic relationship of the design and construction of full coverage restorations with regard to esthetic appearance and gingival health. Esthetic appearance with full coverage restorations is dependent on anatomic form, the materials used, and the maintenance of gingival health.

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CONCLUSION The change in dentistry from need based dentistry to elective dentistry has made a significant impact on the profession and the public perception of dentists. It is estimated that up to one half of the dentistry accomplished at this time is elective. Much of this treatment is what could be considered to be esthetic dentistry including bleaching, bonding, veneers, tooth colored inlays and onlays, non metallic crowns and fixed prosthesis, orthodontics and surgical procedures, and many other procedures.

Dentists and their staff must be proactive in their patient educational activities to stimulate patients to desire these elective procedures. If dentists ask for patients to ask for the procedures, practice activity can be influenced negatively.

This dissertation will assist interested persons in becoming updated in the broad scope of esthetic dentistry. Self instruction is perhaps the best way to cope with the expanding area of esthetic dentistry.

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2. Christensen GJ. Ensuring retention for crowns and fixed prostheses. J Am Dent Assoc. 2003 Jul;134(7):993-5.

3. Flores-Mir C, Silva E, Barriga MI, Lagravere MO, Major PW. Lay person's perception of smile aesthetics in dental and facial views. J Orthod. 2004 Sep;31(3):204-9; discussion 201.

4. Frindel F. Sixteen keys for building a youthful smile J Orthod . 2003 Mar;74(1):83-102.

5. Gillet D, Miquel JL, Jeannel A. Patients, practitioners, faculty and dental esthetics: the same level of perception? Odontostomatol Trop.

2002 Jun;25(98):5-11.

6. Ibbetson R. Clinical considerations for adhesive bridgework. Dent Update. 2004 Jun;31(5):254-6, 258, 260 passim.

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1978 Sep;40(3):244-52.

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J Prosthet Dent. 1977 Sep;38(3):243-8.

10. Mac Arthur DR. Are anterior replacement teeth too small? J Prosthet Dent 1987; 57:462-465.

11. Mack MR. Vertical dimension: a dynamic concept based on facial form and oropharyngeal function. Prosthet Dent. 1991 Oct;66(4):478-85.

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12. Magne P, Magne M, Belser U. The esthetic width in fixed prosthodontics. J Prosthodont. 1999 Jun;8(2):106-18.

13. Matthews TG. The anatomy of smile. J Prosthet Dent 1978; 39:128-134.

14. McArthur DR. Determination of approximate size of maxillary anterior denture teeth when mandibular anterior teeth are present. Part III: Relationship of maxillary to mandibular central incisor widths. J Prosthet Dent. 1985 Apr;53(4):540-2.

15. Naylor CK. Esthetic treatment planning: the grid analysis system. J Esthet Restor Dent. 2002;14(2):76-84.

16. Neves FD, Mendonca G, Fernandes Neto AJ. Analysis of influence of lip line and lip support in esthetics and selection of maxillary implantsupported prosthesis design. J Prosthet Dent. 2004 Mar;91(3):286-8.

17. Olsson KG, Furst B, Andersson B, Carlsson GE. A long-term retrospective and clinical follow-up study of In-Ceram Alumina FPDs. Int J Prosthodont. 2003 Mar-Apr;16(2):150-6.

18. Rosenstiel SF, Ward DH, Rashid RG. Dentists' preferences of anterior tooth proportion--a web-based study. J Prosthodont. 2000 Sep;9(3):12336.

19. Simon J. Using the golden proportion in aesthetic treatment: a case report. Dent Today. 2004 Sep;23(9):82, 84.

20. Smukler H, Chaibi M. Periodontal and dental considerations in clinical crown extension: a rational basis for treatment. Int J Periodontics Restorative Dent. 1997 Oct;17(5):464-77.

21. Vig RG, Brundo GC. The kinetics of anterior tooth display. J Prosthet Dent. 1978 May;39(5):502-4.

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22. Weinberg LA. Esthetic and the gingiva in full coverage. J Prosthet Dent 1960;10:737-744.

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