Matrices/ orthodontic course by indian dental academy


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Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.

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Matrices/ orthodontic course by indian dental academy

  1. 1. INTRODUCTION In the late 1800’s the need for a matrix became apparent when dentists recognized that the best way to treat a tooth affected by dental caries on the approximal surfaces was by restoring its anatomical contour and contacts with adjacent tooth. The matrix was needed to provide the missing wall or walls and thus contain the restorative material during the filling of the prepared cavity. Until the late 1800’s, the rationale for treating carious lesions on the approximal surfaces of teeth was based on either a restorative or a prophylactic concept. EARLY CONCEPTS OF TREATING APPROXIMAL CARIES Restorative concept The rationale for restorative treatment was to remove the caries and fill the cavity with a suitable material. At this time, however, restoration of the tooth to form and function was not of general concern. Prophylactic concept The rationale for prophylactic treatment was premised on an early theory of caries, which taught that caries began at the point of contact between the teeth where pressure damaged the enamel - the lesion being caused by the action of external corrosive agents. 1
  2. 2. The method advocated the creation of a self - cleansing space by removing diseased or healthy tooth structure from the approximal surfaces, thereby achieving total and permanent separation of teeth. The self - cleansing space was indicated for the prevention of caries, for the treatment of superficial caries, and to provide access to deep caries. The procedure was accomplished by the use of a file, the oldest method of removing tooth structure. The procedure as described by HARRIS(1848) required the removal of one - third or more of the tooth and created a shoulder at the cervical margin to maintain contact in this area and prevent the teeth from drifting. In the posterior regions, the separation was referred to a V - shaped space. If the teeth required restorations, they were designed so as not to encroach on the space created. Even with these improvements however, the results observed by the general practitioner led to condemnation of the procedure by the profession at large. The main criticism of this technique, voiced by patients and the practitioners and patients alike, concerned the disfigurement of teeth. Not only did patients complain of disfigured teeth, they also complained of impaction of food on the gingivae and sensitivity of teeth due to exposed dentin. 2
  3. 3. By 1887, the technique was contraindicated. CONTOURED FILLINGS Around 1890, practitioners changed the way they restored teeth that had approximal lesions. The concept was premised on a new theory of caries, which taught the caries began below, not at the contact point of the teeth as with the early theory of caries(MILLER 1904) and advocated the restoration of the natural, or original contour and contact of the tooth. As such a contoured filling 1. Would reestablish the proper form of the inter - proximal space 2. Maintain the function of the teeth 3. Ensure no breach in the continuity of the occlural aspect of the dention. 4. Maintain the length of the arch 5. Prevent impaction of food 6. Maintain and promate the health of the gingivae as well as the comfort of the patient Thus BLACK(1890) brought a new and different meaning to the ‘V - shaped’ space . An additional concept introduced 3
  4. 4. concurrently prescribed extending the margins of the approximal surfaces of the cavity on to facial and lingual surfaces of the tooth. This concept not only facilitated the placement of contoured fillings, but also placed the cavity margins within the range of protective influences, reducing the possibility of recurrent caries. EARLY MATRICES The early advocates of contoured fillings included W. H Atkinson, M .H WEBB and S.H GUILFORD. They recognized that to fill a prepared cavity and produce a contoured filling the practitioner required assistance in containing the filling material without such assistance , over contour at the cervical level and under contour at the occlusal level resulted. The assistance came in the form of a matrix, which provided for the missing walls of the prepared tooth and transformed a cavity of two, three or more surfaces into a simple one. In addition the matrix could be molded to assist in re- establishing the natural contours of the tooth. Early in its use, the matrix was subject to criticism. Some believed that when a tooth was to be restored with direct filling gold, the matrix did not allow for enough contour of gold to compensate for the subsequent polishing and adapted too closely to the 4
  5. 5. margins, thus providing the potential for inadequate condensation of gold in these areas especially at the cervical area. ORIGINAL MATRIX 1. JACK MATRIX 2. HUEY MATRIX 3. PERRY MATRIX 4. BRUNTON MATRIX (A) CUSTOM MATRICES I. Anatomic matrices II. Tie band matrix III. Continuous loop matrix 1.Shellac matrix Perry matrix Herbst 2.Herbst matrix Clapp matrix Newkirk modifi 3.Hutchinson matrix Fillebrown matrix Soldred matrix 4.Hand matrix Black matrix Spot welded 5.Woodward matrix Andrews matrix Tinner’s joint 6.Rubber matrices Baker matrix Welded circumferential (i) Danforth matrix Abernethy matrix Rivet matrix (ii) adapto matrix Hallenback matrix Collar / band modification 7.Sweeny matrix Markley modification Harrison 5
  6. 6. 8.Ingraham - -----matrix Hampson modification Copper band 9.Sectional matrix with Pinch band Bi- ting ring 10.Open face matrix (B) MATRICES WITH RETAINERS Although the early matrices were intended for use with direct filling golds, these matrices were also recommended for use with amalgam which has been introduced to America in 1830’s. Because of its plasticity amalgam required a matrix for the condensation and development of proper physical properties, contour and inter proximal contact. THE ORIGINAL MATRIX The first recorded use of a matrix is of that introduced by DWINELLE(1855). The matrix consisted of a band made from a broad, thin piece of dense gold. The band was wedged firmly against the tooth. However it was opened against the cervical margin of the cavity of the preparation to allow space for condensation of excess gold. Although his own personal testimony and that of his peers (Brophy 1886 , Jack 1887) point Dwinelle as the originator of the matrix. Later, the original matrix was described as the metal band that was wedged against and supported by the adjacent tooth, but was not attributed to any one inventor. 6
  7. 7. IMPROVEMENTS ON THE ORIGINAL MATRIX With the new concept of contoured fillings, the matrix took on added significance. The earliest matrices incorporating the new concepts appeared in the late 1800’s and included the JACK, HUEY, PERRY and BRUNTON MATRICES. As a group, these matrices used various materials of unspecified thickness for the band. The materials included steel, platinum plate or foil, brass, copper, phosphor - bronze, German silver and tin. Few of these bands were precontoured. JACK MATRIX Jack matrix introduced in 1871, was accepted as the first matrix to satisfy the concept of contoured fillings. The matrix consisted of a slight wedge shaped piece of steel hollowed out to create a depression on its face to correspond to the desired contour. The band was made in assorted sizes and shapes and was put into place with forceps, the Adjacent tooth used for retention. The band was then wedged with a boxwood wedge. MATRICING 7
  8. 8. Matricing is the procedure whereby a temporary wall is created opposite to the axial walls surrounding areas of tooth structure that were lost during tooth preparation. It is used with restorative materials that are introduced in a plastic state. OBJECTIVES The matrix should 1. Displace the gingivae and rubber dam away from the cavity margins during introduction of the restorative material. 2. Assure dryness and non-contamination of the details and the space to be covered with and occupied by the setting restorative material. 3. Provide shape of the restoration during the setting of the restorative material i.e band materials should be unyielding to the enregies of insertion. 4. Maintain shape during the hardening of the materila. 5. Confine the restorative material within the cavity proparation and predetermined surface configration. MATRICES FOR CLASS I CAVITY PREPARATIONS Double banded Toffelmire for class I. 8
  9. 9. Turn the large vice moving knob until the slotted vice is about ¼ inch from the inner end of the retainer. Loosen the screw until its painted end is clear of the slotted vice. Make a loop out of the universal band creating an edge with a narrow circumference. The narrow circumference is placed gingivally and the wide circumference edge is placed occlusal. The free ends of the band are inserted into the vice while the looped end of the band extends away from the retainer. Always be sure the slotted end of the vice is facing gingivally. This will facilitate easy occlusal removal of the retainer. Tighten the vice screw to lock the band in the vice. Guide the looped end of the band gently over the tooth. The size of the loop may be increased or decreased by turning the vice moving knob. With the band in position around the tooth, tighten the vice moving knob. Ideally the retainer should be parallel and adjacent to the facial surfaces of the quadrant of the teeth being operated on. An additional small piece of matrix band material is that contoured to the facial or lingual axial configuration of the contemplated restoration and inserted between the tooth and the 9
  10. 10. previously positioned and retained matrix in the area of the facial or lingual extension of the cavity preparation. This piece of material should overlap over the margins of the extension by about 1.5 - 2mm circumferentially. With a beaver-tail burnisher, create a separation between the two bands. Select a wedge that will create and maintain the proper separation between the two bands and thereby enable the formation of the proper contour facially and / or lingually. Cover the wedges with softened compounds and insert it between the two bands and cool to harden. MATRICES FOR CLASS II CAVITY PREPARATIONS a) SINGLE-BANDED TOFFELMIRE FOR CLASS II This is the most practical matrix for class II cavity preparations. Its use is made universal by the easy application and removal of the band to and from its holder without disturbing the condensed material. PROCEDURE The basic steps are repeated from the previously described double banded arrangement. 10
  11. 11. If the cavity preparation involves one proximal surface only and there is a substantial difference between the heights of the interproximal gingiva on the mesial and distal sides of the tooth, the matrix band should be trimmed so that it is narrower on the side where the interproximal gingiva is more occlurally located. It may also be possible to use matrix bands with only one gingival projection, which should coincide with the proximal side where the interproximal gingiva is more apically located. If the gingival extension of the proximal portion of the cavity preparation is more apically located than gingival lines facially and lingually, there is a danger of cutting the gingival tissues facially and lingually in using a band with a straight gingival edge. In this situation it is necessary to reduce the occlusal - apical width of the band facially and lingually or to use a band with apical projections which coincide and cover the gingival extension of the proximal portion of the cavity preparation. In preparation with subgingival margins, especially at the axial angles or any surface protrusion of the tooth, the edges of the band occasionally encounter the gingival margin and become bent inward, preventing further seating of the band. For this reason there should be unprepared, exposed tooth surface apical to the gingival margin of the preparation to support the band in its apical path and to prevent its inward collapse or bending. This may necessitate gingival retraction or cutting. 11
  12. 12. Also in these situations, the band edges should be guided in their apical path by placing a flat - bladed, blunt instrument between the band and the adjacent unprepared tooth surface apical to the gingival margin. Although it is preferable to put the retainer in the buccal vestibule, parallel to the adjacent teeth, sometimes, due to shallow sulcus or sizable buccal involvement of the tooth in a activity preparation, the retainer is placed on the lingual. This usually necessitates a contrangled retainer. However a retainer should never be located at right angle to the facial or lingual surfaces of the teeth operated upon as this will drastically change the occluso-apical contour of the band. As soon as the band is in place and all cavity margins can be seen inside the matrix, a wedge, comparable to the dimensions of the future gingival embrassure is chosen and tied(always from the opposite side of the retainer attachment). Using a ball burnisher from within the cavity preparation, shape the matrix material to create the out line of the contact and contour of the future restoration. If the cavity has buccal or lingual extension, repeat the modifying steps in the double-banded Toffelmire application. For all Toffelmire applications, after the insertion and initial hardening and manipulation of the restorative material, the wedges 12
  13. 13. and secondary band are removed. Then the retainer is loosened and disengaged. The primary band is bent against adjacent tooth surfaces and removed from between the teeth in an occlusal direction, while being pressed against the adjacent tooth. If the contact area is extremely tight and the band is resistant to removal, it is a good idea to cut the band on the opposite side of the retainer, remove the roughened portion of the band and then pull it buccal-lingually with pressure against the adjacent tooth. b) IVORY MATRIX NO.1 The band encircles a posterior proximal surface so it is indicated in unilateral class II cavities. c) IVORY MATRIX NO.8 The band encircles the entire crown of the tooth so it is indicated for bilateral class II cavities. d) BLACK’S MATRICES i)Black’s matrix for simple cases is recommended for a majority of small and medium size cavities PROCEDURE Cut a metallic band so that it will extend only slightly over the buccal and lingual surfaces of the tooth. 13
  14. 14. To prevent a wrap, around holding ligature from slipping off the band and the band sliding gingivally. The corners of the gingival ends are turned up to hold the ligature. ii) BLACK’S MATRIX with a gingival extension to cover the gingival margin of a subgingival cavity. In this form of extension is created in the occluso-gingival width of a band to cover the gingival margin of a subgingival cavity. The retaining procedures are the same as for the previous type of Black’s matrix. e) SOLDERED BAND OR SEAMLESS COPPER BAND MATRIX These are indicated for badly broken teeth, especially those receiving pin retained amalgam restorations, with large buccal and lingual extension i.e Class II design preparation PROCEDURE A stainless steel band is cut according to the measured diameter of the crown of the tooth, then the two ends are soldered together or a seamless copper band is selected so that it barely clears the diameter of the tooth in the cervical area. Either the band could be heated in a flame until it glows red light. It is then quenched in alcohol thus softening the band for easy handling. 14
  15. 15. With curved scissors, fasten the band so its gingival periphery corresponds to the gingival curvature and the CEJ. The band is then smoothed to remove rough edges cervically and occlusally. With containing pliers contour the band to produce the proper shape in the contact area. Areas of the band in the contact area are reduced to a paper thinness using a coarse sand paper disc. Then they are recontoured . Next the band is seated on the tooth and tightened at the cervical end by pinching a ‘tuck’, using a flat bladed plier at the gingival edge in the area accessible to the plier. To stabilize the band and prevent cervical flashes of amalgam, wedges are placed gingival to the cervical margin of the preparation. The external portions of the matrix and the wedges are covered with compound to further stabilize the matrix. A wire is inserted facio- lingually in the compound to further stabilize it. Apply a heated ball burnisher from the inside of the cavity to the band, softening the external compound and insuring the proper contour, contacts and embrasures. After condensation and initial covering, the compound is removed and the matrix is cut at the area of the tuck. 15
  16. 16. With a plier or hemostat, grip the band at either side of the scissors, cut and tear through each thinned contact portion to remove the band without damaging the proximal region of the amalgam. f) THE ANATOMICAL MATRIX This is the most efficient means of reproducing contacts and contour. It is entirely hand made and contoured specifically, for each individual case. It is specially useful in mutilated teeth. It is indicated for class II designs. PROCEDURE A piece of “0.001 - 0.002” stainless steel matrix band 1/8th in width is drawn between the handle of a pair of festooning scissors. This procedure facilitates the adaptation of the free ends of the matrix to the proximal surface of the tooth. The matrix is cut to proper length. It must extend well beyond cavity margins. To obtain a proper length the center’s of the proximal buccal and proximal lingual cusps are used as a guide. The matrix band is contoured with contouring pliers. The band is then trimmed so that the matrix will extend well below the gingival margin of the cavity and at least 2mm beyond the buccal & lingual margin of the cavity. 16
  17. 17. A wedge is selected and shaped to conform to the gingival embrasures, and it is then placed in warm water to soften it slightly. Two small cones of compound are warmed in hot water. These compound cones are forced one at a time, using thumb and finger pressure into the buccal and lingual embrasures. The pressure is maintained until the compound has flowed evenly over the entire buccal and lingual surface of the adjacent teeth. A wire staple is constructed from a paper clip. The staple is heated in a flame and forced into the compound in the buccal and lingual embrasures. This adds to the stability of the matrix by locking together the 2 pieces of the blacking compound. A warm ball burnisher is used to soften any compound that has been forced between the matrix and the adjacent tooth. The matrix is burnished lightly against the contacting tooth. After initial hardening of the inserted restorative material, the compound is cracked at its occlusal junctions using a sharp chisel or knife. The wedges are removed using a hemostat and the band is curled backwards against the adjacent tooth and withdrawn buccolingually, with pressure against the adjacent proximal surface. 17
  18. 18. g) ROLL - IN - BAND MATRIX (Auto matrix) h) S - SHAPED BAND This is used for class II cavity preparations. Procedural instructions are exactly as described in class III preparations 3)MATRICES FOR A CAVITY PREPARATION FOR AMALGAM RESTORATION ON THE DISTAL OF THE CUSPID a) The S - shaped matrix This is an ideal matrix for class III cavity preparation on the distal of the cuspid, with either a labial or lingual access. PROCEDURE One half to one inch of regular strip matrix 0.001 - 0.002 in thickness is used. A mirror handle is used to produce the S-shaped in the strip. The band is contoured over the labial surface of the cuspid and the lingual surface of the adjacent bicuspid. With contouring pliers, the strip is contoured in its middle part to create desired form for the restoration. It is then placed inter proximally and wedged firmly apical to the gingival margin and covered with compound at its facial and lingual ends. The remaining procedure is similar to those of the anatomic matrix. 18
  19. 19. 4) MATRICES FOR CLASS III DIRECT TOOTH COLOURED RESTORATIONS These are usually transparent plastic matrix strips. For resin’s cellophane strips are used. Mylar strips may also be used. a) Matrix for class III preparations with teeth in normal alignment. The suitable plastic strip is burnished over the end of a steel instrument. Eg :- handle of a tweezer , to produce a BELLY in the strip. This will allow for curvature which if properly contoured and designed, will reproduce the natural proximal contour of the tooth. The strip is cut to allow the belly to be placed where the contact is desired. In placing a plastic strip between the teeth, it should be cut as wide as the tooth is long. The corners of the strip should be trimmed therefore , to allow for better adaptation to the tooth and to prevent any excess material from forming on and beyond the facial or lingual margins. The length of the strip should be just sufficient to cover the labial and lingual surfaces of the tooth. A wedge is trimmed and applied to hold the strip in place. For labial approach use fingers of the left hand for holding the strip firmly against the lingual surface of the tooth while the material is being placed in the cavity. 19
  20. 20. b) Matrix for class III preparation in teeth with irregular alignment PROCEDURE A suitable plastic strip is contoured and adopted as described previously and then removed. For a labial approach preparation a compound impression is taken of the lingual surface. The compound is allowed to overlap the adjacent teeth. It is cooled and then removed. The compound impression should show an imprint of the cavity preparation. The compound impression is then warmed. The surface is softened without distorting the form of the entire impression. This can be done by holding the impression close to the flame only for a moment. The strip is then placed into position again, followed by the compound impression against the strip, assuring perfect adaptation of the matrix to the cavity on the lingual surface. The material is then introduced from the labial. c) MATRIX FOR TWO SMALL PROXIMAL PREPARATIONS IN CONTACT WITH EACH OTHER An appropriate plastic strip is folded with one end slightly longer than the other. 20
  21. 21. A loop ½ inch in diameter is formed in the matrix strip. The loop is flattened and ceased with a finger, making a T - shaped and trimmed. The trimmed matrix is then placed between the teeth. For labial approach preparations, the strip is held over the lingual surface with the finger while the cavities are filled. 5) MATRICES FOR CLASS IV PREPARATIONS FOR DIRECT TOOTH COLOURED MATERIALS a) The plastic strip for inciso proximal cavities PROCEDURE A suitable plastic strip is folded at an angle into an L - shaped then sealed with a plastic cement or any adherence that does not react with tooth coloured material.  One side of the strip is cut so that it is as wide as the length of the tooth.  The other side is cut so that it is as wide as the width of the tooth.  The strip with a wedge in place is adapted to the tooth b) ALUMINIUM FOIL INCISAL CORNER MATRIX 21
  22. 22. These are ‘stock’ metallic matrices shaped according to the proximo - incisal corner and surfaces of anterior teeth. They can be adapted to each specific case. PROCEDURE A corner matrix closest in size and shape of the lost area of the tooth is selected. It is trimmed gingivally so that it coincides with the gingival architecture and covers the gingival margin of preparation. As it is readily deformable, shape it with the thumb and first finger until it fits the mesio distal and labio - lingual dimensions of the tooth. Loosely place the wedge allowing space for the matrix band thickness. Partially fill the preparation and then the corner matrix preferably after venting the corner. Apply the partially filled matrix over the partially filled tooth preparation at its predetermined location between the loosened wedge and the tooth. c) TRANSPARENT CROWN FORM MATRICES These are ‘stock’ plastic crowns which can be adapted to tooth anatomy. • In bilateral class IV preparations use the entire crown form. 22
  23. 23. • In unilateral class IV cut the plastic crown inciso - gingivally into two halves and use only the side corresponding to the location of the preparation. PROCEDURE Choose the crown form with the size and shape close to the tooth to be restored. For a unilateral class IV, after cutting the crown from inciso - gingivally, so that the correct incisal angle of the crown form matches the last tooth incisal angle. If for bilateral class IV keep the crown as it is. Trim the crown form gingivally, so that it coincides with the gingival architecture and completely covers the gingival margin of the preparation. Check the matrix to ensure that it will recreate proper contact and contour. Then remove the matrix and thin it at its contact area with a sand paper disc. It should be perforated at the incisal angle. Completely fill the matrix with the restorative material and partially fill the preparation with the restorative material. Place the filled crown form on the tooth in the desired location. The wedge is then tightened. d) ANATOMIC MATRIX 23
  24. 24. Prior to preparing the teeth, study model for the affected tooth together with at least one intact adjacent tooth on each side is made. It is preferable, especially in multiple involvement. The defective area is restored on the study model in a fairly heat resistant material ( plaster, acrylic resin, blacking compound, plasticine, etc) to the appropriate configuration. A plastic template is made for the restored tooth on the model using a comb of heat and suction consequently to draw the mouldable material onto the study model. The template is trimmed gingivally to fit the tooth and adjacent peridontal architecture. It should seal on atleast one unprepared tooth on each side. This is the matrix which should be vented by perforating the corners of its part corresponding to the future restoration. 6) MATRICES FOR CLASS V AMALGAM RESTORATION a) WINDOW MATRIX This matrix is formed using either a Tofflemire matrix or copper band matrix. PROCEDURE FOR USING THE TOFFLEMIRE MATRIX 24
  25. 25. The contrangle retainer is applied at the side of the tooth that does not have the preparation. A window is cut in the band slightly smaller than the outline of the cavity (perforated windowed bands are available). Wedges are placed mesially and distally to stabilize the band. PROCEDURE FOR USING THE COPPER BAND A seamless copper band is selected that is just larger than the prepared tooth. Fasten and adjust the band to the tooth. A window is cut coinciding with the cavity but smaller in diameter. The edges are smoothed. b) THE S - SHAPED MATRIX This is usually indicated for a proximal extension of a buccal or lingual class V preparation. 7) MATRICES FOR CLASS V PREPARATIONS FOR DIRECT TOOTH COLOURED RESTORATIONS a) Anatomic matrix for non light cured direct tooth colored materials. PROCEDURE The class V cavity may be preliminary filled with inlay wax or gutta - percha and trimmed to the proper contour. The wax and the tooth are then coated with cocoa butter or mylar strip and 25
  26. 26. compound impression is taken of the tooth surface to be restored. Adjacent surfaces are to be included in the impression. After the compound has cooled, it is removed and the wax is removed from the cavity. A mix of the restorative material is made and placed into the cavity, and the compound matrix is placed into position and held securely in place under pressure until the material sets. SUMMARY / CONCLUSION Although there have been very few investigations conducted on this subject, it is clear that no matrix technique is capable of the exact replication of normal anatomic contour of restored teeth. • Overall the anatomic matrix procedures must closely reproduce normal tooth contours. • Wedging is universally imperative in order to eliminate cervical flash of restorative material. • Some of the clinical significance is the fact that circumferential matrix bands retained by tightening devices(Toffelmire) have been shown to deform tooth structures. Passively inserted matrix bands like anatomic matrix and T - shaped bands etc have no deformative effect on the remaining tooth structure. 26