FACIAL ANALYSIS- ORTHODONTIC DIAGNOSIS
INDIAN DENTAL ACADEMY
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soft tissue analysis •
Four parts will be presented
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Facial keys to orthodontic diagnosis and treatment planning. part I
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Facial keys to orthodontic diagnosis and treatment planning. part II
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Soft tissue cephalometric analysis; diagonsis and treatment planning
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The four stage treatment planning process for class II and classIII CASES
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Facial keys to orthodontic diagnosis and treatment planning..
Part I G. William Arnett, DDS and Robert T. Bergman, DDS, MS Santa Barbara, Calif www.indiandentalacademy.com
PURPOSE OF ARTICLE (1) to present an organized, comprehensive clinical facial analysis and 2
to discuss the soft tissue changes associated with orthodontic and surgical treatments of malocclusion.
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• Patients are examined in natural head position, centric relation, and relaxed lip posture. • Nineteen key facial traits are analyzed.
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• Three questions are asked regarding the 19 facial traits before treatment: • (1) What is the quality of the existing facial traits? • (2) How will orthodontic tooth movement to correct the bite affect the existing traits (positively or negatively)? • (3) How will surgical bone movement to correct the bite affect the existing traits (positively or negatively)? www.indiandentalacademy.com
HISTORY • Several lines and angles have been used to evaluate soft tissue facial esthetics.
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H -ANGLE • . Ten degrees is ideal when the convexity measurement is 0 mm. • Holdaway said the ideal face has an Hangle of 7° to 15°, which is dictated by the patient's skeletal convexity www.indiandentalacademy.com
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E-LINE
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• Ricketts also described soft tissue by relating beauty to mathematics. The divine proportion was used by the ancient Greeks (ratio of 1.0 to 1.618) and was applied by Ricketts to describe optimal facial esthetics.
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• • A patient with normal FMA, IMPA, FMIA, and ANB measurements usually has a Zangle of 80° as an adult and 78° as a child 11 to 15 years of age.
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Z-ANGLE
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• Scheideman, Bell, et al. studied the anteroposterior points on the soft tissue profile below the nose. •
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Sn -vertical
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• Worms and othersdiscussed lip assessment for proportionality, interlabial gap, lower face height, upper lip length, and lower lip length.
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• Another measurement used to study the soft tissue is the angle of convexity described by Legan and Burstone • This is the angle formed by the soft tissue glabella, subnasale, and soft tissue pogonion. www.indiandentalacademy.com
• The zero meridian line, developed by Gonzales-Ulloa, is a line perpendicular to the Frankfort horizontal, passing through the nasion soft tissue to measure the position of the chin. • The chin should lie on this line or just short of it. www.indiandentalacademy.com
• The Steiner esthetic plane and the Riedel plane have also been used to describe the facial profile.
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• It is widely accepted that orthodontic tooth movement can alter esthetics • Case believed the facial outline should be regarded as an important guide in determining treatment when correcting a malocclusion. • He recommended extraction of teeth to retract procumbent lips www.indiandentalacademy.com
• Angle related esthetics to the position of the maxillary incisor. • In evaluating facial beauty, Tweed concentrated on the position and inclination of the mandibular incisors in relation to the basal bone.
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• The soft tissue covering the teeth and bone can vary so greatly that the dentoskeletal pattern may be inadequate in evaluating facial disharmony. •
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• Facial imbalance may be associated with lip inadequacy or lip redundancy caused by lip length, underlying tissues being out of balance, or a problem in tissue thickness o
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• Burstone presented the idea that correcting the dental discrepancy does not necessarily treat the facial imbalance and may even cause facial disharmonies. •
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• Drobocky studied 160 four first premolar extraction patients and concluded that "Ten to 15 percent of cases could be defined as excessively flat (dished-in) after treatment.“ • Park and Burstone23 studied 30 cases in which the lower incisor was 1.5 mm anterior to the A-Pog line . www.indiandentalacademy.com
• This relationship is proposed by some orthodontists as the key to an esthetic profile. • The profiles of these 30 patients were found to be grossly different therefore casting doubt on the reliability of the incisor-to-A-Pog line as a reliable esthetic guideline. www.indiandentalacademy.com
LIMITATION OF CEPHALOMETRICS • Another source of cephalometric inadequacy in facial diagnosis and treatment planning is the cranial base. • When the cranial base is used as the reference line to measure the facial profile, bogus findings can be generated.
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• Michiels studied 27 nonorthodontic, Class I patients to test the validity of various popular cephalometric measurements used to predict clinical profiles. His conclusions were that • (1) measurements involving cranial base landmarks are inaccurate in defining the actual clinical profile; www.indiandentalacademy.com
• 2) measurements involving intrajaw relationships were slightly more accurate in reflecting the true profile; • (3) no measurement is 100% accurate; and • (4) the soft tissue thickness and axial inclination of incisors are the most important variables in inaccuracy. www.indiandentalacademy.com
• Wylie analyzed 10 patients using five popular cephalometric analyses and found only 40% agreement on treatment planning. He concluded that "cephalometrics should not be the primary diagnostic tool for dentofacial diagnosis.“ • www.indiandentalacademy.com
• Many cephalometric norms have been based on patient populations that had no skeletal disharmonies. When these "normal values" from normal populations are applied to anterioposterior and vertical skeletal disharmonies they lose validity.
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• Further problems with cephalometric diagnosis relate to the anatomic areas studied.
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• Facial analyses developed with cephalometric x-ray films, such as those by Holdaway, Merrifield,Burstone,and others, focused primarily on anterioposterior orthodontically alterable dimensions of the face. • www.indiandentalacademy.com
• Complete analysis requires incorporation of vertical and transverse assessment of bite and facial needs.
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• Still another problem with cephalometric diagnosis and treatment planning is that the norms may not be accurate because of different soft tissue posturing. • In some studies, the soft tissues were not in a repose position when measurements were made www.indiandentalacademy.com
• This is particularly disruptive in the vertical dimension. Vertical skeletal diagnosis depends on assessment of the soft tissues in repose. • Because early studies examined the patient in the closed lip position, reliable norms for relaxed lip position may be lacking. www.indiandentalacademy.com
• Closed lip position may be useful when no skeletal deformity exists, but in the case of skeletal deformity the closed lip posture is not accurate in terms of diagnosis and treatment planning.
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• Burstone and others noted that nose length, lip length, and nasolabial angle are important aspects of facial esthetics .
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• Models, cephalometrics and facial analysis together should provide the cornerstones of successful diagnosis • .
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• Models and/or clinical bite examination indicate to the practitioner that bite correction is necessary. • Facial analysis should be used to identify positive and negative facial traits and therefore how the bite should be corrected to optimize facial change needs.
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FACIAL KEYS TO ORTHODONTIC DIAGONOSIS • In this system, the cephalometric x-ray film is not used for diagnosis, but rather as an aid to try treatment options in the form of visual treatment objectives (VTO). •
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• The purpose of the VTO is to assess how tooth and bone movement used to correct the bite will impact the face.
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• An example of this is correcting a Class II occlusion with either a LeFort I impaction, mandibular advancement, or upper first premolar extractions with headgear and Class II elastics. All three treatments correct the bite but change the face in different ways.
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• The procedure selected should balance the face optimally. Facial examination can determine the best treatment for achieving facial balance, whereas cephalometric analysis has been shown to be unreliable.
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• The most important point in proper analysis of facial esthetics is the use of a clinical format.
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• Natural head posture, • centric relation (uppermost condyle position), • and relaxed lip posture • www.indiandentalacademy.com
• Natural head posture is preferred because of its demonstrated accuracy over intracranial landmarks. • Natural head posture has a 2° standard deviation compared with a 4° to 6° standard deviation for the various intracranial landmarks in use
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• Natural head posture is the head orientation the patient assumes naturally • . Patients do not carry their heads with the Frankfort horizontal parallel to the floor. • Therefore this landmark should not dictate head posture used for treatment planning. www.indiandentalacademy.com
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• When skeletal changes are made relative to natural head position appropriateness is ensured in the resulting soft tissue profile.
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CENTRIC RELATION • All examination data should be recorded in centric relation since orthodontic and surgical results are strictly in this position to produce precise function • If head films are taken in a postured position, all interarch relationships are incorrect. www.indiandentalacademy.com
• Posturing of the mandible can decrease the severity of Class II • can increase the severity of Class III relationships .
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Class II CASE
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CLASS III CASE
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Centric relation can be established as follows • 1. Patient in a 45° sitting position. • 2. Use a warmed, double-thickness piece of pink base plate wax. • 3. Guide the opening and closing to first tooth contact, nondeflected position.
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• . The wax bite is used for head films, tomograms, model mounting, and facial analysis. This ensures consistency of data and treatment results.
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RELAXED LIP POSITION --------------------------------
The relaxed lip position is obtained while the patient is in centric relation by the following method 1. Ask the patient to relax. 2. Stroke the lips gently. 3. Take multiple measurements on different occasions. 4. Use casual observation while the patient is unaware of being observed. www.indiandentalacademy.com
• The patient should be in the relaxed lip position because it demonstrates the soft tissue, relative to hard tissue, without muscular compensation for dentoskeletal abnormalities.
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• Vertical disharmony between lip lengths and skeletal height (vertical maxillary excess, vertical maxillary deficiency, mandibular protrusion, mandibular retrusion with deep bite) can not be assessed without the relaxed lip posture.
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• Existing positions and needed changes in upper incisor exposure, interlabial gap, lip length, and proportion are lost in the closed lip position. • Closed lip position may be adequate for normoskeletal cases but is totally inadequate for skeletal disharmony assessment www.indiandentalacademy.com
• When the lips contact (distortion), the bite should be opened by placing a wax bite between the teeth until the lips separate in the repose posture. • By using this open bite posturing, lip length and position distortion is avoided. Soft tissue cosmetic problems can then be assessed relative to needed bite changes. www.indiandentalacademy.com
OPENING THE BITE TO ACCESS LIP LENGTHS
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ASSESSMENT OF OPEN BITE
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• With the natural head posture, centric relation, and relaxed lip position, the patient is visualized in all three planes of space: • 1. Anterior-posterior • 2. Transverse • 3. Vertical www.indiandentalacademy.com
• This examination consists of 19 of these traits. • Inclusion of a trait within the study was dependent on the high significance of the trait to successful orthodontic and surgical facial outcomes. • Examination of key traits in three planes of space was necessary. The normal values are a combination of previous studies and 20 years of surgical experience. www.indiandentalacademy.com
DIFFERENT VALUES FOR SAME TRAIT • An example of the BURSTONE 73.8+_ 8 variability is the nasolabial angle LEGAN 102+- 8 FARAKAS
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99.1+-8.7
Many reasons exist for the inconsistency between different study norms (Table II), including the following
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. Different racial origins within the study populations. 2. Some studies contained malocclusions, whereas some studies had normal bites or Class I occlusions only. 3. Some studies were in closed lip positions, whereas others were in relaxed lip position. 1
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• 4. Some studies used head films oriented to cranial base structures, others were in natural head position. • 5. Some values were from clinical measurement, although most were from cephalometric x-ray films. • 6. The exact way of measuring the same trait may be different from one study to the next. • 7. Some studies contained patients who were not fully grown. www.indiandentalacademy.com
• Due to the discrepancy of norms, each patient being examined should be studied with norms appropriate to that patient (race, age, lip posture, head orientation).
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-------------------------------By asking the following three questions, the best treatment plan becomes apparent:
• -------------------------------• 1. What is the quality (good or bad) of the existing facial traits? • 2. How will the orthodontic tooth movement to correct the bite affect the existing traits (positively or negatively)? • www.indiandentalacademy.com
• 3. When surgery is necessary, which surgery (maxilla, mandible, or both) will be necessary to normalize negative and maintain positive facial traits while correcting the bite
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• • • • •
Four possible treatments exist for each patient: (1) orthodontics alone , (2) orthodontics plus lower jaw surgery, (3) orthodontics plus upper jaw surgery and (4) orthodontics plus both upper and lower jaw surgery. • The treatment that optimizes occlusion (bite and TMJ harmony), facial balance, stability, and periodontal health is chosen. If treatment harms the patient, it should not be rendered. www.indiandentalacademy.com
• Nineteen facial traits were selected for this examination • . Two views of the patient are used for identification of problems in three planes of space:
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• I. Frontal A. Relaxed lip B. Functional analysis 1. Closed lip 2. Smile • II. Profile A. Relaxed lip www.indiandentalacademy.com
FRONTAL VIEW
• Natural head posture, • centric relation, • and relaxed lip posture are used to accurately assess the frontal view.
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-------------------------------Outline form and symmetry • 1 The widest dimension of the face is the zygomatic width • The bigonial width is approximately 30% less than the bizygomatic dimension. • www.indiandentalacademy.com
• Farkas has established normal values for height and width. • The height to width proportion is • 1.3:1 for females • and 1.35:1 for males. •
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• An alternative to measuring height and width is to artistically describe the face. Faces are wide or narrow, short or long, round or oval, square or rectangular.
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Frontal view
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• Will orthodontic and/or surgical care necessary for bite correction correct or accentuate existing height and width imbalance? • An example of orthodontic correction of heightwidth imbalance is the use of bite opening mechanics to lengthen the face during bite correction. • An example of surgical correction is maxillary impaction to shorten the long face. www.indiandentalacademy.com
• The extremes of disproportion are short and wide or long and narrow. • Short, square facial outlines are indicative of deep bite Class II malocclusion, vertical maxillary deficiency, and in some cases, masseteric hyperplasia. •
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• Long, narrow faces are associated with vertical maxillary excess or mandibular protrusion with dental interferences leading to open bite. • The bizygomatic dimension is often deficient (cheekbone deficiency) in combination with maxillary retrusion. • The bigonial dimension may be deficient in combination with mandibular retrusion. www.indiandentalacademy.com
• Height and width disproportion is corrected in two ways: • 1. Maxillary or mandibular surgery is used simultaneously to correct the bite and to lengthen or shorten the facial height. • 2. Augmentation or reduction of the facial height or width www.indiandentalacademy.com
• Examples of the latter are • chin lengthening to increase facial height (H to Me'), • cheekbone augmentation to increase the bizygomatic width (Zy to Zy), • or augmentation of the mandibular angles to increase the bigonial dimension (Go' to Go'). • Buccal lipectomies can help reduce excessive width in the submalar cheek areas. www.indiandentalacademy.com
• -------------------------------• As a general rule, the maxilla should rarely be moved up and back. • This movement decreases lip support, increases the nasolabial folds, decreases incisor exposure, and can make the facial outline appear short and wide. • These changes give the appearance of premature facial aging. www.indiandentalacademy.com
ASSYMETRY • The most common to least common sites of facial asymmetry are • chin, mandibular angles, and cheekbones.
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• Correction of asymmetries are accomplished with • (1) cant correction or midline movement of the maxilla and mandible simultaneous with occlusal correction or • (2) augmentation or reduction of the skeletal surfaces.
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• Examples of the latter include unilateral cheekbone, angle, or body augmentation. • A common asymmetry correction is chin shifting to the right or left to center the chin on the facial midline.
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FACIAL LEVEL • To examine facial levels a reliable horizontal landmark line is necessary. • With the patient in natural head posture, the pupils are assessed for level with the horizon. • • Structures compared with the pupil line are • (1) upper canine level, • (2) lower canine level, and • (3) chin and jaw level. www.indiandentalacademy.com
-------------------------------Facial level
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• -------------------------------• If the pupils, in natural head posture, are not level to the horizon, a constructed frontal horizontal reference line is used. This line is visualized as follows: • 1. Frontal natural head posture. • 2. Horizontal line parallel to the horizon through the pupil area. • 3. Assess other structures relative to this line www.indiandentalacademy.com
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Midline alignments • Midlines are assessed with uppermost condyle position and first tooth contact. • If occlusal slides alter joint position, no reliable midline assessment can be made. •
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• The relative positions of soft tissue landmarks (nasal bridge, nasal tip, filtrum, chin point) and dental midline landmarks (upper incisor midline, lower incisor midline) are noted.
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• . Filtrum is usually a reliable midline structure and can be used as the basis for midline assessment most often. • When the pupils are level in natural head posture, a vertical line through filtrum midpoint is used to assess other hard and soft tissue midline structures
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Pupils not aligned
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• Dental midline shifts are the result of multiple dental factors including: • 1. Spaces • 2. Tooth rotations • 3. Missing teeth • 4. Buccally or lingually positioned teeth • 5. Crowns or fillings which change tooth mass • 6. Congenital tooth mass difference from left to right www.indiandentalacademy.com
• Dental midline shifts are treated orthodontically. • Asymmetric premolar extractions may be necessary to align dental and skeletal midlines. • Skeletal midline shifts are not corrected orthodontically, surgery is employed. www.indiandentalacademy.com
• When the dental and skeletal midlines deviate together, the etiologic factor is usually skeletal, and surgery is used to correct (i.e., chin and lower incisor midline are 3 mm to the left). • . Attempts to orthodontically correct the bite when the etiologic factor is skeletal can produce buccal plate violation and gingival recession
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Facial one thirds
The face divides vertically into thirds from hairline to midbrow, midbrow to subnasale, and subnasale to soft tissue menton (. The thirds are within a range of 55 to 65 mm, vertically www.indiandentalacademy.com
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The hairline is variable, and the upper third is frequently low range. Increased lower one-third height is frequently found with vertical maxillary excess and Class III malocclusions (lack of interdigitation opens vertical height). Decreased lower one-third height is associated with vertical maxillary deficiency and mandibular retrusion deep bites. www.indiandentalacademy.com
• Production of correct proportion influences the choice of surgical procedure used to correct the occlusion (i.e., maxillary impaction to correct Class II malocclusion associated with long lower one-third rather than mandibular advancement).
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• The equality of the middle and the lower thirds should not be used as the determining factor in facial height changes. • The appearance of the landmarks (incisor exposure, interlabial gap) within the lower third are more important in assessing balance than are the equality of the thirds www.indiandentalacademy.com
Lower third
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-------------------------------Lower one-third evaluation • Upper and lower lip lengths • The lips are measured independently in a relaxed position . • The normal length from subnasale to upper lip inferior is 19 to 22 mm. •
If the upper lip is anatomically short ( 18 mm or less), an increased interlabial gap and incisor exposure is seen with a normal lower face height.
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• This should not be confused with vertical maxillary excess (increased interlabial gap, increased upper incisor exposure, increased lower one-third facial height).
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• The lower lip is measured from lower lip superior to soft tissue menton and normally measures in a range of 38 to 44 mm. • • (lower incisor tip to hard tissue menton; • women, 40 mm ± 2 mm, • and men, 44 mm ± 2 mm). www.indiandentalacademy.com
• Anatomic short lower lip should not be confused with a short lower lip secondary to posture (upper incisor interferences) seen in Class II deep bite cases with normal anterior dental height. • Anatomic short lower lip can be lengthened with a lengthening genioplasty.
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• anatomic long lower lip can be associated with Class III malocclusions. • This should be verified with the cephalometric anterior dental height measurement.
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• A closed lip position will produce a long lower lip in combination with increased lower facial height (vertical maxillary excess and Class III) as the lip elongates to close. • The closed lip length is misleading and should not be used for treatment planning. • The normal ratio of upper to lower lip is 1:2. www.indiandentalacademy.com
• Lip redundancy is seen in cases of vertical maxillary deficiency and mandibular retrusion with deep bite and, rarely, long lip lengths. • To accurately assess lip lengths with redundant lips, the patient's bite must be opened until the lips separate
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Upper lip to incisal edge
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Upper tooth to lip relationship • . The distance from upper lip inferior to maxillary incisal edge is measured . • The normal range is 1 to 5 mm. • Women show more within this range. •
Surgical and orthodontic vertical changes are based primarily on this measurement (i.e., postsurgical incisor exposure range of 1 to 5 mm). • Conditions of disharmony are produced by four variables: www.indiandentalacademy.com
• Conditions of disharmony are produced by four variables: • 1. Increased or decreased anatomic upper lip length (infrequently). • 2. Increased or decreased maxillary skeletal length (frequently). • 3. Thick upper lips expose less incisor than thin upper lips, all other factors being equal. www.indiandentalacademy.com
• 4. The angle of view changes the amount of incisor visible to the viewer. •
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• overimpaction of upper incisor teeth leads to the appearance of premature aging, especially in conjunction with maxillary retraction. • This type of surgical movement is rarely indicated. • www.indiandentalacademy.com
• Posterior movement of the maxillary incisors is indicated only for true maxillary protrusion. • Orthodontic overretraction, which is used to occlusally correct mandibular retrusion, produces premature aging of the face.
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Interlabial gap • . With the lips relaxed, a space of 1 to 5 mm between upper lip inferior and lower lip superior is present • . Females show a larger gap within the normal range. • This measurement is also dependent on lip lengths and vertical dentoskeletal height. www.indiandentalacademy.com
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• • • •
Increases in interlabial gap are seen with anatomic short upper lip, vertical maxillary excess, and mandibular protrusion with open bite secondary to cusp interferences.
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• Decreased interlabial gap is found with vertical maxillary deficiency, • anatomically long upper lip (natural change with aging, especially in males), • and mandibular retrusion with deep bite.
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• Abnormalities should be considered when planning skeletal changes. • An anatomically short upper lip should be recognized as a soft tissue problem and should not be treated by excessively shortening the maxilla. • This can lead to a short, round facial outline. www.indiandentalacademy.com
Closed lip position.
• Even though an understanding of relaxed lip position is essential, an understanding of closed lip position adds support to diagnostic patterns. The closed lip position also reveals disharmony between skeletal and soft tissue lengths. www.indiandentalacademy.com
• Increased mentalis contraction (mentalis strain), lip strain, and alar base narrowing are observed in vertical skeletal excess, anatomic short upper lip and some cases of mandibular protrusion with open bite.
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Smile position lip level • When examining the smile posture, different lip elevations are observed in normal and abnormal skeletal patterns. • Ideal exposure with smile is threequarters of the crown height to 2 mm of gingiva, females more than males.
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• 1 Variability in gingival exposure is related to • (1) lip length, • (2) vertical maxillary length, • (3) maxillary anatomic crown length, • and (4) magnitude of lip elevation with smile. www.indiandentalacademy.com
• Because of etiologic variability, surgical shortening of the maxilla is indicated only when excess gingival exposure is found in combination with increased interlabial gap, increased tooth exposure, increased lower face height, and/or mentalis strain.
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• Deficient exposure etiologic factors include a • long upper lip, • vertical maxillary deficiency, • and/or minimal smile lip elevation • . www.indiandentalacademy.com
• Decreased incisor exposure is treated with maxillary lengthening when found in combination with decreased interlabial gap -lip redundancy, • short lower one-third face height, • and normal upper lip length.
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• When impacting or lengthening the maxilla on the basis of reposed incisor exposure, gingival smile exposure should also be considered. For example, if the patient has normal smile gingival exposure (1 to 2 mm) and the incisors are lengthened to treat decreased relaxed lip incisor exposure, excessive smile gingival exposure will result www.indiandentalacademy.com
• Particular care should be taken with short clinical crowns. • A 3 to 4 mm repose incisor exposure may expose unacceptable amounts of gingiva when smiling because of short maxillary incisor crowns. • This situation is properly treated by placing normal length crowns (veneers) on the maxillary incisors and treatment planning from the repose and smile perspective. www.indiandentalacademy.com
PROFILE VIEW • Natural head posture, centric relation, and relaxed lips are used to accurately assess profile.
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Profile angle
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• This angle is formed by connecting soft tissue glabella, subnasale, and soft tissue pogonion • General harmony of the forehead, midface, and lower face is appraised with this angle. • Maxillary and mandibular basal bone anteroposterior discrepancies are easily visualized. www.indiandentalacademy.com
• Class I occlusion presents a total facial angle range of 165° to 175°. • Class II angles are less than 165°, • • and Class III are greater than 175° www.indiandentalacademy.com
• Skeletal discrepancies producing Class II angulation include maxillary protrusion (rare), vertical maxillary excess (common), and mandibular retrusion (common). • Class III skeletal patterns include maxillary retrusion (common), vertical maxillary deficiency (rare), and mandibular protrusion (common). www.indiandentalacademy.com
• . The profile angle is the most important key to the need for anteroposterior surgical correction. •
When values are less than 165° or greater than 175°, skeletal malocclusions needing surgery are probably the cause. • Angles at the extreme of normal (greater than 175° or less than 165°) are usually caused by skeletal disharmony. • Soft tissue thickness differences are not capable of causing these extreme angle changes. www.indiandentalacademy.com
Nasolabial angle
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• This angle is formed by the intersection of the upper lip anterior and columella at subnasale • This angle can change noticeably with orthodontic and surgical procedures that alter the anteroposterior position or inclination of the maxillary anterior teeth www.indiandentalacademy.com
• . All procedures should place this angle in the cosmetically desirable range of 85° to 105°. • Female patients will usually be more obtuse within this range. :
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Factors to be considered in treatment planning to correctly achieve this angle are as follows 1. Existing angle. 2. Tilting versus bodily movement of maxillary teeth (orthodontic and surgical) and predicted effect on the existing lip position. 3. www.indiandentalacademy.com
• Estimation of lip tension present. • Tense lips may move more posteriorly with tooth and basal bone movement and less anteriorly. • Flaccid lips may move less with posterior tooth and basal bone movement and less with anterior.
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• 4. Anteroposterior lip thickness • . • Thin lips (6 to 10 mm) may move more with tooth retraction movement than thick lips (12 to 20 mm).
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OVERJET • The magnitude of the mandibular retrusion (overjet). • the larger the overjet distance, the more retraction of the maxillary incisors will be necessary, thus opening the nasolabial angle.
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• 6. The following factors affect the anteroposterior movement of incisor teeth after extractions: • Amount of anterior crowding, • spaces, • tooth mass proportion (upper versus lower), • posterior rotations, • curve of Spee (upper versus lower), • and anchorage (headgear, Class II elastics). www.indiandentalacademy.com
7. Extraction versus nonextraction. 8. Extraction pattern (first versus second premolars).
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• If the nasolabial angle is open (approximately 105°), • retraction of anterior teeth orthodontically and surgically should be avoided in treatment planning. • Likewise, a long nose will become adversely prominent with lip retraction. • Present limited knowledge of how lips respond to anteroposterior movement of the teeth dictates a conservative approach when large movements are contemplated.
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• . • As a general rule, the maxilla should not be moved posteriorly in treating dentofacial deformities, especially in combination with superior repositioning.
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• This creates nasal elongation, alar base depression, and opening of the nasolabial angle, all of which create facial premature aging..
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Maxillary sulcus contour
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• • • • •
Maxillary sulcus contour (MxSC) is subjectively assessed. The contour is described as either accentuated, gentle curve (normal) or flat. Measurement of this contour is impractical. www.indiandentalacademy.com
• Normally this sulcus is gently curved and gives information regarding upper lip tension • . With lip tension, the sulcus contour flattens. • Flaccid lips form an accentuated curve with the vermilion lip area showing an accentuation of curve • . www.indiandentalacademy.com
• The flaccid lip generally is thick (12 to 20 mm from anterior vermilion to labial incisor) giving the lip (i.e., headgear with Class II elastics or functional appliance treatment) the appearance of being too far forward relative to the teeth
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• The maxilla should not be retracted significantly when a deeply curved, thick lip is present since this produces poor lip support and cosmetics. • If possible, the maxilla should be moved forward into a thick, curved lip to improve lip support. www.indiandentalacademy.com
Mandibular sulcus contour
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Mandibular sulcus contour (MdSC) is subjectively assessed. The contour is either accentuated, gentle curve (normal) or flat. Measurement of this contour is impractical. www.indiandentalacademy.com
• Orbital rim projection is measured from the anterior most globe (Gb) to the orbital rim point (OR). A subjective orbital rim description is also given: Normal, flat, or protruded.
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• The orbital rim is an anteroposterior indicator of maxillary position. Deficient orbital rims may correlate positionally with a retruded maxillary position because the osseous structures are often deficient as groups, rather than in isolation..
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• The globe normally is positioned 2 to 4 mm anterior to the orbital rim • The surgical maxillary versus mandibular decision is influenced by the orbital rim position. Deficient orbital rims dictate maxillary advancement, all other factors being equal www.indiandentalacademy.com
Cheekbone contour
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• Cheekbone contour is anteriorly facing, curved line that starts just anterior to ear, extending forward through cheekbone point (CP), then extending anteriorinferiorly ending at maxilla point (MxP) adjacent to alar base of nose.
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• For descriptive purposes the cheekbone contour is divided into three areas: (1) zygomatic arch, (2) middle contour area, and (3) subpupil areas.
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• The CP is located 20 to 25 mm inferior and 5 to 10 mm anterior to the outer canthus (OC) of the eye when viewed in profile . When viewed frontally the CP is 20 to 25 mm inferior and 5 to 10 mm lateral to the OC .
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• . CP and MxP indicates osseous cheekbone and maxillary base positions, respectively.
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• The nasal base-lip contour (Nb-LC) extends inferiorly from the maxilla point (MxP) as a gentle, anteriorly facing curve, ending just below and lateral to the mouth commissure.
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• In normoskeletal patients the cheekbonenasal base-lip contour complex is a smooth continuation, anteriorly facing, curved line. • This line, when viewed frontally or from the side, is a definite flowing curve with no interruptions which are apparent with skeletal deformities. www.indiandentalacademy.com
• Maxillary retrusion is indicated by a straight or concave contour at MxP . When this anatomic area is concave or flat, maxillary advancement is necessary.
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•Mandibular protrusion interrupts the nasal base-lip line in the length of the upper lip (F When the line is interrupted within the height of the upper lip a mandibular setback may be indicated.
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NASAL ROJECTION • The nasal projection (NP) measured horizontally from subnasale to nasal tip is normally 16 to 20 mm • Nasal projection is an indicator of maxillary anteroposterior position.
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throat length and contour
• The distance from the neck-throat junction to the soft tissue menton should be noted . • No millimeter measurement is necessary, but a planned mandibular setback will change this length. The predicted esthetic result should produce a normal appearing length without sagging. www.indiandentalacademy.com
• This length becomes particularly important when contemplating anterior movement of the maxilla. • Decreased nasal projection contraindicates maxillary advancement. With a Class III malocclusion, short nose, and all other factors equal, mandibular setback is indicated. www.indiandentalacademy.com
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• Throat length (TL) is assessed from neckthroat point (NTP) to soft tissue menton (Me'). This distance is subjectively described as either normal, long or short length, and with or without sag.
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• A patient with a short, sagging throat length is not a good candidate for mandibular setback. A long, straight throat length is amenable to mandibular setback.
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• Often a mandibular setback is necessary with chin augmentation to balance lips with chin and maintain throat length. • Suction lipectomy is a useful adjunct for controlling submental sag with setbacks or when isolated fat accumulation is present.
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• . Subnasale-pogonion reference line is generated through points subnasale (Sn) and soft tissue pogonion (Pg'). Lip projections are evaluated relative to this line.
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Subnasale-pogonion line • (Sn-Pg') • Burstone reported that the upper lip is in front of the Sn-Pg' line by 3.5 mm ± 1.4 mm, and the lower lip is in front of the line by 2.2 mm ± 1.6 mm.16
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• The relationship of the lips to the Sn-Pg' line is an important aid in orthodontic soft tissue analysis and treatment. Tooth movement changes the relationship of the lips to the Sn-Pg' line and therefore the esthetic result. • All tooth movements should be assessed in regard to the anticipated lip change to the Sn-Pg' line. www.indiandentalacademy.com
• Extractions should be avoided when they move the teeth and create retraction of the lips (dished-in) behind this line The relationship of the lips to this line is affected by the following factors:
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• 1. Skeletal relationship: When anterior or posterior skeletal disharmony exists, producing overjet abnormalities (positive or negative), the Sn-Pg' has no validity. • 2. Incisor inclinations: With a Class I skeletal pattern, the upper and lower incisors must be at proper overjet and axial inclination to produce proper protrusion of the lips relative to the SnPg' line. www.indiandentalacademy.com
• 3. Lip thickness: The lip relationship to the Sn-Pg' line is dependent on lip thickness. The Burstone relationship16 is true only if the lips are the same thickness, all other factors being ideal..
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• Class I incisors (upper incisor in front of lower incisor) produce Class I lips (upper lip in front of lower lip) only if the lips are of equal thickness
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• This line is also used when planning surgery on the VTO • The Sn-Pg' line is ideally drawn to the lips through subnasale. If Pg' is significantly posterior to the line, a chin augmentation is indicated. Female chins are softer relative to this line. www.indiandentalacademy.com
SOFT TISSUE CHARACTERISTICS OF COMMON SKELETAL DEFORMITIES
• With the 19 facial keys, 8 pure skeletal deformities with predictable soft tissue appearances can be defined. • The greater magnitude of the skeletal deformity the more distinct the soft tissue pattern. • www.indiandentalacademy.com
• Skeletal deformities may occur in combination (i.e., vertical maxillary excess with mandibular prognathism) and facial traits are therefore blended. I • in all cases, facial traits are helpful in diagnosing skeletal problems. The eight uncombined or pure or unmixed anteroposterior facial-skeletal types are as follows: www.indiandentalacademy.com
• A. Class I facial and dental (facial angle Class I) • 1. Vertical maxillary excess • 2. Vertical maxillary deficiency
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Class I occlusion and chin projection can occur in combination with vertical maxillary excess or vertical maxillary deficiency. The anteroposterior profile is normal, but the vertical height of the face is long or short.
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B. Class II facial and dental (facial angle 3. Maxillary protrusion 4. Vertical maxillary excess www.indiandentalacademy.com 5. Mandibular retrusion
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• . Class II bite and chin projection can be produced by entirely different skeletal patterns. • axillary protrusion, mandibular retrusion and vertical maxillary excess all can produce identical bites with similar chin profiles. www.indiandentalacademy.com
• C. Class III facial and dental (facial angle Class III) • 6. Maxillary retrusioin • 7. Vertical maxillary deficiency • 8. Mandibular protrusion
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ORTHODONTIC PREPARATION FOR SURGERY --------------------------------
Extraction patterns and mechanics are aimed at removing dental compensations before surgery. Compensation removal leads to better facial results. An example of this is a 10 mm skeletal mandibular retrusion. Incisor dental compensations to the overjet may decrease the 10 mm overjet to 5 mm. www.indiandentalacademy.com
If the mandible is advanced with the compensations present, the chin deficiency is still 5 mm. In contrast, when dental compensations are removed, the 10 mm overjet and 10 mm chin retrusion are simultaneously and totally corrected with surgical advancement. • www.indiandentalacademy.com
• The most common appropriate extractions for routine facial-skeletal deformities are as follows: • A. Class I facial and dental (chin in balance with the face) • 1. Vertical maxillary excess— variable • 2. Vertical maxillary deficiency— variable www.indiandentalacademy.com
• B. Class II facial and dental (chin retruded) • 1. Maxillary protrusion— lower second and/or upper first premolars, orthodontic correction. No surgery required. • 2 www.indiandentalacademy.com
• . Vertical maxillary excess— upper extraction based on extent and location of crowding, lower extraction based on effects on upper lip support when LeFort I is done to correct vertical maxillary excess. • 3. Mandibular retrusion— upper second premolar and/or lower first premolars www.indiandentalacademy.com
• C. Class III facial and dental (chin protruded) • 1. Maxillary retrusion— upper first and lower second premolars • 2. Vertical maxillary deficiency— upper first and lower second premolars • 3. Mandibular protrusion— upper first and lower second premolars www.indiandentalacademy.com
• An additional benefit of the surgical extraction pattern is that the anticipated surgical relapse becomes the opposite of the orthodontic relapse pattern
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• . An example of this is mandibular advancement with lower first premolar extractions that have uprighted the lower incisors.
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• Surgical relapse is posterior, and orthodontic relapse at the lower incisors is anterior, in the opposite direction. The orthodontic relapse is a mechanism to compensate for surgical relapse.
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