WEDGES 1. INTRODUCTION Wedges are used to bring about rapid separation of teeth and stabilization of the matrix band. A contoured matrix band in the retainer will still be deficient in two respects for the formation of an adequate amalgam restoration. First, the forces of condensation of amalgam will usually cause an excessive contour at the cervical area as well as an over extension of the restorative material in an apical direction. This resulting â€œoverhangâ€? can be minimized or avoided by wedging the matrix band tightly against the cervical area of the tooth just below the gingival floor. 2. CLASSIFICATION Basically wedges can be differentiated into: A. Wooden or plastic / polyester wedges. This can be further classified as: A. 1a) Preformed wedges or b) Custom made wedges Eg: Orange wood stick, oak wood etc. 2 a) Medicated wedges Eg: Haemo wedges or b) Non-medicated wedges Eg: Orange wood stick 3 a) Synthetic wedges Eg: Synthetic resins
or b) Natural wedges (Eg: Orange wood, Soft pine) B. Depending upon the shape, they are classified as a. Triangular (anatomic) wedges (âˆ†) (Triangular in cross section). b. Round wedges
(O) (Round in cross section)
3. FUNCTIONS Wedges perform the following functions: i.
They assure close adaptability of the matrix band to the tooth and prevent cervical flash of material.
They occupy the space designated to be the gingival embrasure, preventing the restorative material from impinging on it, thus assuming proper health for the gingival inter dental papillae (col).
They define the gingival extent of the contact area as well as the facial and lingual embrasures, thereby assuring the health of the proximal periodontal tissues.
They create some separation to compensate for the thickness of the matrix band and minor drifting of the teeth.
They establish atraumatic retraction of the rubber dam and the gingiva from the gingival margin of the cavity preparation, thereby producing a temporary haemostasis and minimize moisture in an area which will receive moisture sensitive dental materials.
They assure the immobilization of the matrix band against movement both facio-lingually and cervico-occlusally during insertion of the restorative material.
They protect the interproximal gingiva from unexpected trauma.
They prevent the matrix band from springing open under pressure.
Advantages of wooden wedges: Round toothpick wedge placed in the gingival embrasure protects the gingiva during proximal boxing. It is preferred with conservative proximal boxes because its wedging action is more occlusal (near the gingival margin) than with the triangular wedge. Triangular wedge is indicated when deep gingival extension of the proximal box is anticipated because the greatest cross sectional dimension of the wedge is at its base; (consequently it will readily more engage the remaining clinical tooth surface). While the gingival wall is cut, the burâ€™s end corner may at times slightly shave the wedge but will help in preventing unexpected trauma.
Wooden wedges absorb water and swell, thus stabilizing the matrix band and prevent impingement of the restorative material.
Advantage of plastic wedges: Plastic wedges / resin wedges are transparent, thereby they can be used during placement of composite resin restorations as they allow visible light to pass through. They can even be bent or moulded to the configuration of the col. 4. TECHNIQUE FOR PLACEMENT OF THE WEDGE Wedges must be fitted and customized. There is no â€œUniversalâ€? wedge and each one must be fitted for its individually intended space. Trimming can best be accomplished by a scalpel, a gold knife or diamond stone. The effective force of the wedge is horizontally directed to the cervical edge of the band which has been extended approximately 1 mm beyond the gingival margin of the preparation. According to Charbenaeu and Phillips, usually the wedge is inserted into the interdental space from the lingual side because of two reasons : i)
this is the wider of the embrasures.
ii) handle of the matrix retainer comes in the way. According to Sturdevant, facial or lingual wedge placement depends on the operators judgement. (For example, if placement of the wedge from the buccal accomplishes better cervical closure of the band, then this direction of insertion should be selected). Moistening the wooden wedge by submersing it in water permits easier placement and tends to better secure its position.
Forceful use of hardwood wedge causes separation of teeth. If tooth separation is not desired then compressible wedge (soft pine wedge) can be used. Length of the wedge -
A customized wedge may be only 4-6 mm in length.
For anterior teeth, a round wood toothpick approximately 9mm long usually is an excellent wedge.
The wooden wedge should be approximately 5-6 mm long and should be trimmed for proper taper, thickness and width.
Shape of the wedge In well designed long wooden wedges, curvature near the tip prevents damage into the gingival tissues if inadvertently placed. A wooden wedge must be trimmed to fit anatomically within the triangle formed by the matrix band, the adjacent proximal surface and gingival tissue. Break off approximately ½ inch (1.2cm) of a round toothpick. Have a small amount of rubber dam lubricant available. Grasp the broken end of the wedge with the No. 110 pliers and lightly “wet” the gingival aspect of the wedge with the lubricant (Borofax / Vaseline a common therapeutic lubricant).
The wedge should be inserted slightly gingival to the gingival margin wedging the band tightly against the tooth and margin If the wedge is occlusal to the gingival margin, the band will be pressed into
abnormal concavity in the proximal surface of the restoration.
The wedge should not be so far apical to the gingival margin that the band will not be held tightly against the gingival margin. This improper wedge placement will result in a gingival excess or â€œoverhangâ€? caused by the band moving slightly away from the margin during condensation of the amalgam. Such an overhang often goes undetected and causes irritation to the gingiva. Markley in 1982 demonstrated the effectiveness of supporting the matrix material by the blade of a Hollenback carver during the insertion of the wedge for difficult and deep gingival restorations. The tip of the blade is placed between the matrix and the gingival margin and the heel of the blade is leaned against the matrix and adjacent teeth. In this position, the blade supports the matrix to help both in positioning the wedge sufficiently gingivally and preventing the wedge from pushing the matrix into the preparation.
After the wedge is properly inserted, the blade is gently removed.
Test for tightness of the wedge This is done 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. While directing a gentle stream of air, press-drag the tip of the explorer along the gingival margin in both directions to remove any friable enamel. As an additional test, attempt to pull out the wedge using the explorer with moderate pressure, first having set the explorer tip into the wood near the broken end. Moderate pulling should not cause dislodgement. Gingival overhangs can inadvertently occur as a result of wedges becoming loose during amalgam condensation. Assess all aspects of the band and make any desired corrections, once the wedge is placed. Using a mouth mirror again view facially and lingually the proximal aspects of the matrix band to verify that it touches the adjacent tooth and that proper contour has been achieved. (Reflected light must not be seen in the contact area between the band and the adjacent tooth. It creates a false impression of contact resulting from visual overlap of the band and the adjacent tooth). If the band does not reach the adjacent contact area(s) after contouring and wedging, release the tension of the band slightly. If loosening the loop of a
Tofflemire band still does not allow contacting an adjacent tooth, a custom made band with a smaller angle can be used. The placement of wedge can be reinforced by addition of compound or fast setting acrylic resin. Most wedges should be anchored by compound to forestall any loosening of wedges during amalgam condensation. Removal of the wedge is done only after the removal of matrix retainer and band. As long as the wedge is in place, no bleeding will take place when the matrix band is removed. Using the no. 110 pliers, remove the wedge in the direction opposite that of insertion. Often the rubber dam has a tendency to loosen the wedge. This is caused by rebounding the dam from having stretched as the wedge was inserted. This problem can be prevented by stretching the interproximal dam in the direction opposite the wedge insertion before and during the placement of the wedge along with the lubricating of the wedge as described previously. This is accomplished by using a finger tip, first pressing firmly on the dam and underlying soft tissue near the teeth and then pulling the dam as the finger is slightly moved away from the teeth. As the dam is stretched, insertions of the wedge is begun. This procedure will even help prevent catching the rubber dam (or even piercing it) with the leading point of the wedge. For anterior teeth Usually a wedge is needed at the gingival margin to: 1. help hold the polyester / plastic strip in position 2. to provide slight separation of the teeth and 3. to prevent gingival overhang of the composite resin material
Several types of commercial wedges are available in assorted sizes. A triangular shaped wedge (in cross section) is ideal and is indicated for preparations with margins that are deep in the gingival sulcus. Place the wedge using no. 110 pliers from the facial approach for lingual access cavities (and vice versa for facial access) just gingival to the gingival margin. When isolation is accomplished with the rubber dam, wedge placement is aided by a small amount of water soluble lubricant on the tip of the wedge. Wedge placement may result in fracture of the proximal cavosurface tooth structure. If this occurs, reconditioning of that area must occur. Gingival margins that terminate above the gingival crest may be routinely braced with any wedge that fits the space and props the band against the tooth. It is those cavities whose gingival floors terminate on the root that presents the real challenge. To prop the band against tooth structure in these regions precludes the use of a long wedge. Anatomically and clinically, the interseptal gingiva seem to be more depressible than the adjoining buccal cortical plate. A short wedge of compressible soft wood functions more efficiently here. Although it induces some trauma and bleeding, it remains in position less than 20 minutes and no permanent damage is induced by its presence. The wedge has no handle, therefore it must be pushed outward from the opposite side of insertion with a small condenser.
5. WEDGING SYSTEMS 1. A suitably trimmed tongue blade can wedge a matrix where the intra arch spacing between the teeth is large. 2. Piggy back wedging In this wedging system, if the wedge is significantly apical of the gingival margin, a second, usually smaller, wedge may be “piggy backed” on the first to wedge adequately the matrix against the margin. To be effective, a wedge should be positioned as near to the gingival margin as possible without being occlusal to it. “Piggy back” wedging is particularly useful in patients with recession of interproximal tissue level and / or if the proximal box is shallow gingivally. 3. Double wedging system The gingival wedge should be tight enough to prevent any possibility of an overhang of amalgam in at least the middle two-thirds of the gingival margin. Occasionally, double wedging is permitted if access allows to secure the matrix when the proximal box is wide faciolingually. Double wedging refers to inserting two wedges - one
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. However, double wedging should be used only if the middle two thirds of the proximal margins can be adequately wedged. Because the facial and lingual corners are accessible to carving, proper wedging is important to prevent gingival excess of amalgam in the middle two thirds of the proximal box. 4. 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. To wedge a matrix band tight against such a margin a second pointed
between the first wedge and the band by wedge- wedging system.
Sometimes, however it is impossible to use a wedge to secure the matrix band. The band must be sufficiently tight to minimize the gingival excess of amalgam. Because the band is not wedged, special care must be exercised by placing small amounts of amalgam in the gingival floor and condensing the first 1mm of amalgam lightly but thoroughly in the gingival direction using a larger condenser with firm pressure. Condensation against an unwedged matrix will cause the amalgam to extrude grossly beyond the gingival margin. Obviously without a wedge there will be some excess overcontour, requiring correction by a suitable carver immediately after matrix removal.
SEPARATORS 1. INTRODUCTION Judicious separation of teeth is sometimes required in order to establish convenience for operating. The excellence of operative treatment can be enhanced, and the health of both the teeth and their supporting tissues can be improved by this procedure. Thus tooth separation can promote not only convenience for the operator but also better dental health for the patient. 2. OBJECTIVES Teeth are usually separated for one or more of the following reasons: 1. Making room for the matrix band during condensation of amalgam. This space should be in addition to the mesio-distal dimension of the restoration, not at its expense. This is necessary to create a positive (plus) tight contact. 2. Finishing a restoration: Particularly in the anterior teeth the ease of finishing a restoration can be enhanced by separation of the teeth. 3. Diagnostic analysis: A radiograph may not clearly indicate an initial carious lesion near the contact area. Frequently separation of the teeth will help provide additional diagnostic information. 4. Repositioning of drifted teeth: As a result of dental caries or a faulty restoration, a patient may suffer collapse of the mesial distal contact relationship. The normal volume of supporting tissues between these
teeth is reduced. This unfavourable environment may lead to periodontal problems. Restoration of the tooth in such cases is preceded by repositioning of the teeth. Separation of the teeth aids in return of the proper physiologic volume of the supporting tissues. In addition reestablishing this loss of mesial-distal dimension also may lead to better harmony in the occlusal relationships. 5. It can also be used as a convenience means for facilitating access to proximal cavity preparations (especially Class III preparations). 6. To move teeth occlusally (extrusion) or apically (intrusion) in order to make them restorable. 7. To move teeth from a non-functional or traumatically functional location to a physiologically functional one. 8. To remove foreign bodies impacted proximally that cannot be dislodged by floss or brushes. 3. METHODS OF SEPARATION Tooth separation can be accomplished by two methods viz: A. Slow separation (Previous separation / Delayed tooth movement). B. Rapid separation (Immediate separation). i.
SLOW SEPARATION In this method, the teeth are slowly and gradually forced apart through
the expansive properties of certain materials previously inserted between them.
The chief disadvantage of slow separation is the time consumed. The process often requires several days or weeks and repeated application of the separating material. Its advantages are: 1. Comparative absence of soreness of teeth. 2. Lessening the danger of tearing of the fibres of the periodontal membrane. 3. Ability to force away temporarily, with gutta purcha (one of the materials), swollen tissue from the gingival margins of cavities. Indications for slow separation are when teeth have drifted or tilted considerably, rapid movement of the teeth to the proper position will endanger the periodontal ligaments. Therefore, slow tooth movement, over a period of weeks, will allow proper repositioning of teeth in a physiologic manner. Methods of Slow Separation 1.
Separating wires â€“ Usually employed by orthodontists. Thin pieces of wire (brass ligature
wire, 24 guage) are introduced through the embrasure beneath the contact area. The two ends are twisted to create a separation not to exceed 0.5mm. The twisted ends are then bent into the buccal or lingual embrasure to prevent impingement of the soft tissue or interference with occlusion or food flow. The wires are then tightened periodically to increase the separation. This is a very effective movement
amount of separation will be equivalent to the thickness of the wire. 2.
Gutta percha The material may be used in case of a proximal cavity on a bicuspid or
molar, or of adjoining proximal cavities in the same space on posterior teeth. Soften the gutta percha with heat or by dipping it in eucalyptol compound. Pack the cavity overfull, avoiding the danger of too much pressure on the gingiva, and instruct the patient to use the tooth vigorously. Leave the material in position for several days or weeks and renew it, if necessary, until separation is accomplished. 3.
Over sized temporaries Resin temporaries that are over sized mesio-distally may 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. 4.
Orthodontic appliances For tooth movement of any magnitude, fixed orthodontic appliances are
the most effective and predictable method available. Comparable end results may be achieved by removable orthodontic appliances but they require longer treatment. 5.
Rubber appliance separation A piece of rubber dam correctly lodged in the contact area between two
teeth will induce slow separation. When a strip of rubber dam is stretched, it is
carried easily into the contact area. While the dam is stretched, its excess is trimmed on the labial and lingual sides so that only a small disk of rubber remains at the contact area. In some patients, adequate separation may occur after an hour. In others, it may be desirable to sustain the separating influence for 24 hours or longer. Patients vary greatly in response to this separating force. If this force cannot be tolerated, the patient is instructed to remove the contact rubber disk with a piece of dental floss. Some patients may be taught to place their own separation the night before a dental appointment. Variations in the number and thickness of the rubber dam to be placed in contact area is determined by the conditions present and the operative needs for the case. The total separation will tend to approach the passive thickness of the material used. There are at times when a section of rubber band may be the best separating influence. A separating rubber band is available which is a figure â€œ8â€? in cross-section. This form is convenient for projecting into the contact area. 6.
Separation by Grass Ligature Orthodontic grass line ligature thread has long been used for slow tooth
separation. The thread is passed through the embrasure triangle and a loop is tightly secured around the contact area. A secure surgeons knot is positioned to the buccal or lingual side of the occlusal portion of the contact. Grass line ligature thread is available in several sizes to meet the operatorâ€™s need. After a loop has been firmly secured, the moisture in the field produces a contraction of the thread. The force of contraction will induce a separation of the teeth.
RAPID SEPARATION This is the most frequently used method. Separation usually is
accomplished by using specially fabricated steel appliances which act on either the wedge or traction principle. The first of these separators were invented by Dr. O. A. Jarvis in 1874. The advantages of rapid separation are its quickness and its ability to steady or prevent movements of the tooth itself. Damage can occur in the form of severe impingement on the gingiva, tearing of the periodontal fibres or gouging of cemental surfaces. Mechanical separation is a rapid and easy method for separating teeth. The main disadvantage is pain of too rapid separation. Indications Besides the general indications, it can be used preparatory to slow tooth movement, or to maintain a space gained by slow tooth movement. This type of tooth movement should not exceed the thickness of the involved toothâ€™s periodontal ligament as more separation can tear these ligaments at one site and crush them at the other. In other words, it should not exceed 0-2-0.5mm. Rapid tooth movement can be done by one of the following methods. 1.
Wedge method Separation is accomplished by insertion of a pointed wedge shaped
device between the teeth, in order 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, the greater will be the separation. Occasionally it is
desired that separation be obtained for a moment or two - the stability necessary for long operations is not required. In this case, the wedge principle is permitted and sometimes desirable. The following are examples of these types of separation a.
Elliot separator (often known as the crab-claw separator) It is indicated for short
duration separation that does not necessitate
useful in examining proximal surfaces or in final polishing of restored contacts.
Procedure : Adjust the two opposing wedges of the separator inter proximally so that they are positioned gingival to the contact area, not impinging on he inter dental papillae or the interseptal rubber dam. Move the knob clockwise so that the wedges move towards one another establishing the desired separation. During this procedure, care must be taken to prevent slipping of the edges. b.
Wood or Plastic wedges These are triangular shaped wedges, usually made of medicated wood or
synthetic resin. The wedge is used in conjunction with matrices for inserting plastic restorative materials.
For instantaneous separation of teeth during operative procedures in anterior teeth eg. planing the axial walls, accentuating the line angles or polishing Class III restorations, wedging the nail of the thumb or the first finger between the teeth will make rapid separation which is usually sufficient for these purposes.
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. A number of separators have been developed by dentists since the one by Dr. O.A. Jarvis in 1874 having many excellent features. a.
Notable among them are those by Dr. Safford G. Perry and Dr. W. I. Ferrier known as the Ferrier Double Bow Separator â€“ which have the advantages of being made rigid and of avoiding the wedge principle of earlier separators. With this device, the separation is stabilized throughout the operation. Its advantage is that the separation is shared by the contacting teeth and not at the expense of one tooth. They are available in graduated sizes from No. 1 to No. 6. Nos. 1&2 is
used for separation of most anterior teeth. Size No. 3 is for premolars and size No. 4 to 6 are for molars.
Procedure: The four arms are adjusted so that each will hold a corner of the proximal surface of the contacting teeth. The arms will be gingival to the contact area, yet will not impinge on the rubber dam or gingiva. A wrench applied to the labial or lingual is used to make the desired separation which prevents excessive pressure and possible tissue damage. The bars are turned quarter turn at a time in the direction of the arrow to increase the pressure. Thirty seconds should elapse after each quarter turn to allow time for separation to occur. The bows can be braced with compound on the occlusal surfaces of the teeth to prevent the separator from sliding up the roots as force from the turnbuckles is applied. b.
True separators: Recognizing the value of access to an operation and knowing that most
separators had the handicap of a double bow, one of which was on the operating side of the tooth, Dr. Harry A. True developed the Single Bow “NonInterfering” Separator at the College of Physicians and Surgeons of San Francisco School of Dentistry in Sept. 1943. This was particularly valuable at that time for inconspicuous types of gold – foil restorations in class III cavities.
This device is indicated when continuous stabilized separation is required during the dental operation. Its advantages are that, the separation can be increased or decreased after stabilization and the device is non-interfering. Procedure: Insure that the jaws of the separator are close 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. Apply a piece of softened compound to the teeth under the separator, locking it, thereby introducing it in their buccal and lingual embrasures. Also cover the insical or occlusal surface under the separator with the compound. Another piece of softened compound is applied occlusal to the separator so that it is enclosed within the compound attached to the underlying tooth i.e. stabilized. No compound should be permitted to interfere with the movements of the jaws or the screws. A wrench is now used to move the far (movable) jaws over the approximating tooth, thereby exerting the pressure of separation. The nut in the facial side should be moved first until the jaws touches the surface needed, then that of the lingual side. Repeat the adjustment until the desired amount of separation (closure) is obtained. A tail burnisher may be used during the process to move any septal part of the rubber dam so that it does not become engaged in the jaws of the instrument.
REFERENCES 1. Baum, Phillips and Lund “Text book of Operative Dentistry”. 2 nd edition, 1985; W.B. Saunders Publications. 2. Clifford M. Sturdevant. “The Art and Science of Operative Dentistry”. 2nd edition, 1985; C.V. Mosby Publications. 3. Clifford M. Sturdevant. “The Art and Science of Operative Dentistry”. 3rd edition, 1997; Harcourt Brace and Co. Asia PTE Ltd. 4. Gerald T. Charbeneau. “Principles and Practice of Operative Dentistry”. 3rd edition, 1988; Lea and Febiger Publications. 5. Marzouk M.A. “Operative Dentistry – Modern Theory and Practice”. 1 st edition, 1997; Ishiyaku Euro America Inc. 6. William H.O. Mc Ghee, Harry A. True “A Text Book of Operative Dentistry”. 4th edition, 1989; McGraw Hill Book Co.
WEDGES 1. Introduction
4. Technique of wedge placement
5. Wedging systems
3. Methods of Separation
ii. Traction method REFERENCES