Tooth Separation, Wedges and Control of Moisture Definition Tooth separation or tooth movement is the act of either separating the involved teeth from each other, or bringing them closer to each other or changing their spatial position in one or more dimensions. This is done in order to facilitate the creation of a physiologically functional contact, contour and occluding anatomy in the restored tooth.
Indications for tooth movement 1. To bring drifted, tilted or rotated teeth to their original physiologic position for proper reproduction of proximal surfaces during restoration. This is done to avoid flat or concave proximal surfaces and contact areas in the restoration, and to regain the mesio-distal dimension of the dental arch. 2. To close space between teeth when it cannot be closed by the restoration alone. 3. To move teeth to another location more physiologically acceptable by the periodontium. 4. To move teeth occlusally (extrusion) or apically (intrusion) in order to make them restorable. 5. To move teeth from a non-functional or traumatically functional location to a physiologically functional one.
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6. To move teeth to a more esthetically pleasing position. 7. To move teeth to a position that increases the resistance and retention of a restoration. 8. To create space sufficient for the thickness of the matrix band interproximally. 9. To facilitate access to proximal cavity preparation specially class III preparations. 10. To detect proximal decay. 11. To facilitate polishing of the proximal surface of a restoration. 12. To remove foreign bodies impacted proximally that are not dislodged by floss or brushes.
History : Rapid separators • The first separator was introduced by Dr. O.A. Jarvis in 1874. • A number of separators have been developed by dentists since the one by Jarvis. Notable among them are these by Dr. Safford. G. Perry and Dr. W.I. Ferrier. • Dr. Harry A. True developed the single bow non interfering separator at the college of Physicians and surgeons of San Francisco, School of Dentistry.
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Principals of tooth movement i.
Rapid or immediate tooth movement.
ii.
Delayed or slow tooth movement.
Rapid or immediate tooth movement This is a mechanical type of separation that creates either proximal separation at the point of the separators introduction or improved closeness of the proximal surface opposite the point of the separators introduction. Prior to separation
Open distal contact caused by mesial drifting of first molar due to mesial carious lesion. After separation
Closed distal contact
Opened mesial contact to facilitate instrumentation and restoration.
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Indications for rapid tooth movement Besides the general indications it can be used : 1. Preparatory to slow tooth movement. 2. To maintain a space gained by slow tooth movement. This type of tooth movement should not exceed the thickness of the involved tooths periodontal ligament as more separation can tear the ligaments at one site and crush them at the other i.e. it should not exceed 0.2-0.5mm.
Methods of rapid tooth movement 1. Wedge method examples a. Elliot separator. b. Wood or plastic wedges. 2. Traction method a. True separator. b. Ferrier double bow separator.
1. Wedge method Separation is accomplished by the insertion of a pointed wedge shaped device between the teeth to create separation at that point or closure on the opposite proximal side of the involved teeth. The more the wedge moves facially or lingually greater will be the separation. Examples : Elliot separator
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This is indicated for short duration separation that does not require stabilization. It is useful in examining proximal surfaces or in final polishing of restored contacts. Procedure: Adjust the two opposing wedges of the separator interproximally so that they are positioned gingival to the contact area not impinging on the interdental papillae or the interceptal rubber dam. Move the knob clockwise so that the wedges move towards one another establishing the desired separation.
Wood / Plastic wedges These are triangular shaped wedges usually made of medicated wood or synthetic resin. In cross section the base of the triangle will be in contact with the interdental papillae (gingival to the margin of the proximal cavity). The two sides of the triangle should coincide with the corresponding sides of the gingival embrasure i.e. mesial and distal. The apex of the triangle should coincide with the gingival start of the contact area. The wedge is used in conjunction with matrices for inserting plastic restorative matertial. Wedges perform the following functions i.
They assure close adaptation of the matrix band to the tooth surface.
ii.
They occupy the space designated to be the gingival embrasure preventing the restorative material from impinging on it.
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iii.
They define the gingival, facial and lingual extent of the contact area thus assuring the health of proximal periodontal tissues.
iv.
They create some separation to compensate for the thickness of the matrix band.
v.
They established atraumatic retraction of the rubber dam and the gingiva from the gingival margin of the cavity preparation.
vi.
They
produce
temporary
hemostasis
and
minimizes
moisture
contamination in the area of restoration. vii.
They immobilize the matrix band.
viii.
They protect the interproximal gingiva from the unexpected trauma. Although wedges are supplied in different sizes to suit different
locations, they should not be used as supplied. The wedges should be trimmed to exactly fit each gingival embrasure.
Classification of wedges according to the materials I.
Wooden Eg : Orange wood Plastic Eg : Synthetic.
II.
Preformed Custom made. According to the situation made by Dr. (Orange wood).
III.
Medicated Eg : Hemo wedges. Non medicated orange wood.
IV.
Synthetic : Synthetic resin.
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Natural : Orange wood. Plastic wedges which permit transmission of light are available for use with posterior composite restoration
Advantages 1. Of wood wedges are they can be easily cut and trimmed. -
They absorb water intraorally which causes them to swell, improving their interproximal retention.
2. The main advantages of resin wedges is that they can be plastically molded and bent to correspond with the configuration of the interdental col. Wedge placement : Break off approximately 1.2cm of a round tooth pick. Hold the wedge with a plier. Wet the gingival aspect of the wedge with the lubricant. Insert the pointed tip from the facial or lingual embrasure whichever is larger, slightly gingival to the gingival margin, wedging the matrix band tightly against the tooth and margin.
If the wedge is occlusal to the gingival margin the band will be pressed into the preparation, creating an abnormal concavity in the proximal surface of the restoration.
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“Piggy-back” wedging This technique can be used (1) when proximal box is shallow gingivally (2) interproximal tissue level has receded. If the wedge is significantly apical of the gingival margin a second smaller wedge may be piggy backed on the first wedge to adequately wedge the matrix against the margin.
Double wedging It is permitted, if access allows, to secure the matrix when the proximal box is wide facio-lingually. It refers to inserting two wedges one from the lingual and a second from the facial embrasure. Two wedges help to ensure that the gingival corners of a wide proximal box can be properly condensed as well as to minimize gingival excess.
Wedge – wedging Occasionally a concavity may be present on the proximal surface gingivally of the contact and extending as a fluting onto the root eg : the mesial of the maxillary first premolar. A gingival margin located in this area will be similarly concave.
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To wedge a matrix band tight against such a margin a second pointed wedge can be inserted between the first wedge and the band. Test for tightness of the wedge by pressing the tip of an explorer firmly at several points along the middle two thirds of the gingival margin to verify that the matrix cannot be moved away from the gingival margin.
Selection of wedge shape -
Some operators prefer a triangular shaped wedge (anatomic wedge) because it can be modified by a knife or scalpel blade to conform to the approximating tooth contours.
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The triangular wedge is recommended for the deep gingival margin. When the gingival margin is deep the base of the triangular wedge will more readily engage enough tooth gingival to the margin without causing excessive soft tissue displacement.
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It is also indicated with Tofflemire mesio-occluso distal band.
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The round tooth pick wedge is preferred with conservative proximal boxes because its wedging action is more nearer the gingival margin than with the triangular wedge.
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Traction method This is always done with mechanical devices which engage the proximal surfaces of the teeth to be separated by means of holding arms. These are mechanically moved apart creating separation between the clamped teeth. Examples : Non-interferring true separator.
Indications -
When continuous stabilized separation is required.
Advantages -
Separation can be increased or decreased after stabilization.
-
The device is non interfering.
Procedure Insure that the jaws of the separator are closed together. Apply the jaws closest to the bow against the tooth to be operated upon. The jaws further from the bow will move later in the adjustment. Next the separator is stabilized by applying a piece of softened compound to the teeth under the separator by introducing it in their buccal and lingual embrasure. Also cover the incisal or occlusal surface under the separator and over the separator with impression compound. The movable jaws are moved over the approximating tooth exerting the pressure of separation. The nut on the facial side should be moved first until the
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jaw touches the surface needed then the nut of the lingual side is moved. Repeat the adjustment until the desired amount of separation is obtained.
Ferrier double bow separator
With this device, the separation is stabilized throughout the operation. Advantages : The separation is shared by the contacting teeth and not at the expense of one tooth as with true separator. Procedure : The ferrier separator is available in six different sizes for various positions in the mouth. Each instrument has two pairs of jaws which is placed against the enamel of the proximating surfaces of the teeth to be separated. The arms should be gingival to the contact area. The teeth are moved apart by turning threaded bars on the buccal and lingual sides of the instrument. First one bar should be given two or three quarter turns and the other the same number. This is done with a wrench supplied with the instrument. Compound material is applied gingival and occlusal to the mesial and distal bows as described for the previous separator thereby stabilizing it by attaching it to the underlying teeth.
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Slow or delayed tooth movement Indications When teeth have drifted or tilted considerably rapid movement of teeth to the proper position will endanger the periodontal ligaments. Slow tooth movement over a period of weeks, will allow the proper repositioning of teeth in a physiologic manner.
Methods i.
Separating wires : Thin pieces of wire are introduced gingival to the contact then wrapped around the contact area. The two ends are twisted together to create separation not to exceed 0.5mm. The twisted ends are then bent into the buccal or lingual embrasure to prevent impingement of soft tissue. The wires are tightened periodically to increase the separation. This is a very effective method of slow tooth movement. The maximum amount of separation will be equivalent to the thickness of the wire.
ii.
Oversized temporaries : Resin temporaries that are oversized mesiodistally achieve slow separation. Resin is added to the contact areas periodically to increase the amount of separation which will not exceed 0.5mm per visit.
iii.
Orthodontic appliances : for tooth movement of any magnitude fixed orthodontic appliances are the most effective and predictable method available.
iv.
Gutta percha.
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Control of Moisture Operative dentistry cannot be executed properly unless the moisture in the mouth is controlled. Moisture control refers to excluding sulcular fluid, saliva and gingival bleeding from the operating field. It also refers to preventing the handpiece spray and restorative debris from being swallowed or aspirated by the patient. Several methods and devices are available for creating a dry working field, but isolation of the teeth with the rubber dam is the most ideal. The rubber dam technique is fundamental and essential to routine quality patient care.
The Rubber Dam In 1864 S.C. Barnum a New York dentist introduced the rubber dam into dentistry. Purpose The rubber dam is used to define the operating field by isolating one or more teeth from the oral environment. The dam eliminates saliva from the operating site and retracts the soft tissue. Advantages 1. Dry, clean operating field : Rubber dam isolation is the preferred method of obtaining a dry field.
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2. Access and visibility : The rubber dam retracts the lips, cheeks and tongue. Gingival tissue is also retracted to provide better access and visibility to gingival aspects of the cavity preparation. 3. Improved properties of dental materials : As the rubber dam prevents moisture contamination of restorative materials during insertion. 4. Protection of the patient and operator : The rubber dam protects the patient from aspirating or swallowing small instruments or debris associated with operative procedures. The operator is protected from infections present in the patients mouth. 5. Increased operating efficiency. Disadvantages : i.
Time consuming.
ii.
Patient objection.
Conditions that preclude the use of rubber dam 1. Teeth that have not erupted sufficiently to receive a retainer. 2. Some third molars. 3. Extermely malpositioned teeth. 4. Patients suffering from asthma. 5. Psychological reasons for patient not able to tolerate the rubber dam.
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Materials and Instruments 1. Rubber dam material or sheet The dam material is available in 5 x 5 inch or 6 x 6 inch sheets. Sheets are available in a variety of thickness ranging from. Thin
0.15 mm
Medium
0.2 mm
Heavy
0.25 mm
Extra heavy
0.3 mm
Special extra heavy 0.35 mm The thicker dam is more effective in retracting tissue, more resistant to tearing and recommended for isolating class V cavities – The thinner material has the advantage of passing through the contacts easier. Rubber dam material is available in both light and dark colours. Dark colour is preferred for contrast. Rubber dam material has a shiny and a dull side, because the dull side is less light reflective it is placed facing the occlusal aspect. 2. Rubber dam holder It positions and holds the borders of the rubber dam. Rubber dam holders are of various types and designs. a. Facial frames : b. Cervical traction
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Facial frames provide circumferential stretching around the mouth itself eg :
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Young holder which is a U-shaped frame with small projections for securing the borders of the rubber dam. It is easy to apply and comfortable for the patient.
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Cervical traction has a strap going around the head or neck. Cervical traction provides greater access to the operator but is uncomfortable to the patient.
3. Rubber dam retainer : (Clamp) The clamp is used to anchor the rubber dam to the most posterior tooth to be isolated. The retainer consists of four prongs and two jaws connected by a bow.
Many different sizes and shapes are available with specific retainers designed for certain teeth (such as anterior, premolar, molars). When positioned properly on a tooth the retainer would contact the tooth in four areas, two on the facial surface and two on the lingual surface. This four point contact prevents rocking or tilting of the retainer.
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Retainers are also available as wingless and winged retainers. The winged retainer has both anterior and lateral wings. The wings are designed to provide extra retraction of the rubber dam from the operating field and to allow attaching the dam to the retainer before anchoring it to the tooth after which the dam is removed from the lateral wings. Disadvantage of the winged retainer is that wings interfere with the placement of matrix bands and wedges Retainer Numbers W56 - Most molars W7 - Mandibular molars W8
- Maxillary molars
W4
- Premolars
W2
- Smaller premolars
W27 - Terminal mandibular molar teeth requiring preparations involving distal surface. Modified No. 212 retainer for treatment of cervical lesions. The retainer which is applied after the rubber dam is in placed should be tied with a dental floss for retrieval of the retainer incase it breaks while placing or is accidentally swallowed.
4. Rubber dam punch The punch is a precision instrument having a rotating metal table with six holes of varying sizes and a tapered, sharp pointed plunger. The plunger should be centred in the cutting hole.
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5. Rubber dam retainer forceps The forceps is used for the placement and removal of the retainer from the tooth.
6. Rubber dam napkin The napkin is placed between the rubber dam and the patients skin. It has the following advantages. a. Prevents skin contact with rubber to reduce the possibility of allergic reactions in sensitive patients. b. Absorbs saliva at the corners of the mouth. c. Acts as a cushion. d. Provides a convenient method of wiping the patients lips on removal of the dam.
7. Lubricant A water-soluble lubricant applied in the area of the punched holes facilitates the passing of the rubber dam through the proximal contacts.
8. Modeling compound Low fusing modeling compound is sometimes used to secure the retainer to the tooth to prevent retainer movement during the operative procedure.
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9. Template It is used to mark the correct position of the hole before it is punched. To assure uniformity of rubber borders after applications two landmarks should be kept in mind. For maxillary applications the incisors should lie one inch from the upper border, for mandibular applications the most posterior hole is slightly right or left of the center of the rubber sheet.
High volume evacuators When a high-speed handpiece is used high volume evacuators are preferred for suctioning water and debris from the mouth. The high volume evacuator has a diameter of 10 mm. The tip is usually beveled with the flat surface facing the area being cut. Usually the assistant hold the tip, and they should not push the soft tissues or rest on them.
Saliva ejectors : It removes saliva that collects on the floor of the mouth. The tip has a diameter of 4 mm and is left in the mouth during the procedure. The tip resting on the floor of the mouth, under constant negative pressure can draw delicate soft tissue into its orifice resulting in irritation of the mucosa. The ejector should be inspected frequently to insure against occlusion of the tip.
Cotton rolls and cellulose wafers Absorbents such as cotton rolls and cellulose wafers are helpful for short periods of isolation (eg : examination, polishing). Using a saliva ejector in conjunction with absorbents will further control salivary flow. Cotton rolls
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come in a variety of lengths and sizes. The maxillary teeth are isolated by placing a cotton role in the vestibule. The mandibular teeth are isolated by placing one cotton roll in the vestibule and one between the teeth and tongue. Another popular absorbent medium is the Thita “Dri-Angle�. Inserted in the right or left vestibule it is effective in absorbing secretions from the parotid duct.
Drugs The use of drugs in restorative dentistry to control salivation is rarely indicated and is generally limited to anti-sialogogues like atropine. This is given 5 mgm half hour before the appointment. This will decrease salivary flow but should be avoided in patients with high ocular pressure or with cardiovascular problems.
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Conclusion An important consideration of isolating the operating field is preventing the patient from being harmed during the operation. Excessive saliva and hand piece spray can alarm the patient. Small instruments and restorative debris can be aspirated or swallowed. Soft tissues can be damaged accidentally. Rubber dam, suction devices, absorbents contribute not only to harm prevention but also to patient comfort and operator efficiency.
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