Matrix Systems

DLA 1203- Exam 4

1. Matrix Systems Chapter 38

2. Matrix The matrix is a collective term used to refer to the matrix band and the retainer. The matrix band forms the missing surface or wall and reestablishes the normal contour of the prepared tooth while the tooth is being filled with the restorative material. The matrix band is inserted into the retainer and then placed on the tooth. The retainer is the device which holds the band. It is tightened on the tooth and secures the band in place.

3. Matrix In addition to replacing the missing tooth surface of the cavity preparation, the matrix restores the natural contours of the tooth and the proximal contact with the adjacent tooth. A matrix also contains the restorative material within the walls, thereby preventing any excess material from getting near the gingiva. In addition, the matrix must be stable enough to withstand the pressure of the restorative material being placed in the cavity preparation.

4. Matrix Several different matrices are available, and the type of matrix selected depends on the type of restorative materials being used. For amalgam restorations, the Tofflemire matrix or the AutoMatrix is used. With composite material, a plastic strip matrix, shell matrix, or a sectional matrix system is used. Some dentists use the Tofflemire and AutoMatrix for composites also…

5. Wedge Once the matrix is in place, a wedge (small, triangular piece of wood or plastic) is inserted interproximally against the matrix band or strip near the gingival margin of the preparation.

6. Wedge This wedge holds the band securely in place and also prevents excess filling material from escaping between the tooth and the matrix band. This excess is called an overhang . An overhang can be damaging to the gingival tissues if left in place, so the correct positioning of the wedge is important in order to prevent this from occurring.

7. Wedge The wedge also separates the teeth slightly to compensate for the thickness of the band. This ensures good contact with the adjacent tooth after the band has been removed.

8. Wedges Wedges come in different sizes and are either natural wood, clear, or colored. The clear or transparent wedges are used with light-curing restorative materials. These wedges deflect light into the restoration to ensure a thoroughly cured material without marginal gaps.

9. Wedges They usually come in an assortment kit with various sizes, with the colors marking the different sizes. Some wedges can be altered in shape with a knife, if needed. Once the procedure is complete, the wedges are discarded .

10. Wedges

11. Wedges Wedges are only used when the preparation includes a proximal surface(s). For example, if the tooth had a mesio -occlusal (MO) cavity preparation, only one wedge would be needed on the mesial. On the posterior teeth, either the wooden or plastic wedges can be used. On the anterior teeth, when light-cured materials are used, the plastic wedges are best.

12. Wedges The wedges are usually placed from the lingual on the posterior teeth. This makes placement easier and prevents interference with the retainer. Cotton pliers or a hemostat are used to place and remove the wedges. When placing the wedge, the smallest of the three sides is placed toward the gingiva. The wedge should fill the space and fit snugly

13. Toffelmire Matrix with wedge

14. Tofflemire

15. Tofflemire The Tofflemire retainer has a top (occlusal) side and a bottom (gingival) side. The occlusal side is directed toward the occlusal surface and is the smooth side of the guide channels and the vise. The gingival side is directed toward the gingival tissues and has the diagonal slot on the vise and the open ends of the guide channels.

16. Components of Tofflemire Part Function Frame Main body of retainer. Guide channels Slots in end of retainer that hold matrix band. The slots direct band to right or left of retainer. Vise (locking) Holds ends of matrix band in place in diagonal slot. Spindle Screw-like rod used to secure band in vise. Inner knob (adjusting knob) Adjusts size of matrix band loop by moving vise along retainer frame. Outer knob (locking knob) Tightens and loosens spindle against band in the vise.

17. Different Styles of Retainers

18. Matrix Bands Matrix bands are made of stainless steel and are approximately all the same length. They differ in the shape of one edge and their widths The size and shape of the cavity prep indicate which band is used. The more the prep extends toward the gingiva, the wider the matrix band needs to be. The matrix band is slightly curved and when looped over so both ends meet, the small circumference edge faces toward the gingiva and the larger circumference edge faces toward the occlusal.

19. Matrix Bands

20. Matrix Bands Hold matrix band in smile and loop ends of band together. The smaller circumference, the gingival edge, will be on the top and the larger circumference, the occlusal edge, will be on the bottom.

21. Matrix Bands

22. Matrix Bands Hold Tofflemire retainer with guide channels and slot facing up, and insert the matrix band into vise slot and guide channels

23. Matrix Bands Matrix band is positioned in guide channels for quadrants. (A) Maxillary right/mandibular left. (B) Maxillary left/mandibular right.

24. Matrix Bands (A) By turning the outer knob of the tofflemire retainer, the band will be secured. (B) By turning the inner knob of the tofflemire retainer, the matrix band loop increases and decreases in size.

25. Materials Needed for Placement

26. Matrix Bands

27. Matrix Bands

28. Matrix Bands https://www.youtube.com/watch?feature=player_detailpage&v=RTfaz2YzSBs https://www.youtube.com/watch?feature=player_detailpage&v=XfL7vzfa0gY https://www.youtube.com/watch?feature=player_detailpage&v=2lH1JT4lkQQ

29. AutoMatrix The AutoMatrix is a matrix without a retainer. The stainless steel bands are conical shaped and come in four sizes. The conical shape makes the band easy to burnish (smooth) for better contact in proximal areas.

30. AutoMatrix The bands are circles with autolock loops that lock the matrices on the teeth. The tightening coil on the outside of the band is where the matrix is adapted to the tooth. There is no retainer to obstruct the operator's access or vision. The AutoMatrix comes in a kit that contains the clipping pliers, the tightening device, and bands in assorted sizes.

31. AutoMatrix

32. AutoMatrix To place the AutoMatrix , position the matrix on the tooth following the same criteria as with the Tofflemire . Place the tightening device in the coil and rotate the handle to tighten the band around the tooth.

33. AutoMatrix Once the matrix is securely on the tooth, place the wedges as needed. To remove the AutoMatrix , remove the wedges and then, using the removal pliers, clip the end of the auto-lock loop.

34. AutoMatrix The pliers clip the loop and have a plastic cover to then catch the ends of the loop as they fall after being cut. Open the matrix and slide toward the buccal or lingual while pulling it occlusally .

35. Plastic Strip Matrix The thin, transparent, strip matrix is used with composite, glass ionomer, or compomer restorative materials on anterior teeth The strip can be made of nylon, acetate, celluloid , or resin and is approximately 3 inches long and ⅜ inch wide.

36. Plastic Strip Matrix The functions of the strip matrix are as follows: Provide anatomical contour and proximal contact relation Prevent excess material at the gingival margin Confine the restorative material under pressure while the material is being cured Protect the restorative material from losing or gaining moisture during the setting time Allow the polymerizing light to reach the composite restorative material

37. Crown Matrix The crown matrix form is a thin, plastic form that is shaped like the crown. On anterior teeth when the incisal edge is involved (Class IV restorations), a crown form is often used to restore the tooth.

38. Crown Matrix The crown forms come preformed in various designs and sizes. The restorative material is placed both in the cavity preparation and in the crown form. The crown form is then placed on the tooth. These crown forms are clear and can be used with light-cured materials. Once the restorative material is set, the crown form is removed and the tooth is ready for final contouring and finishing.

39. Sectional Matrix A sectional matrix system is most often used on Class II restorations to restore anatomical contacts. The matrix is stable and produces a tight contact with no overhangs. The system consists of oval matrix bands, rings to hold the matrix bands, and forceps to place the rings. The oval-shaped matrix bands are contoured and come in different sizes. They are slightly thicker than the Tofflemire bands.

40. Sectional Matrix The rings are used to hold the matrix bands in place and usually come in two different sizes. The forceps are designed to open the rings for placement and removal. They are like dental dam forceps except the ends are shorter, broader, and angled slightly for better retention.

41. Sectional Matrix

42. Sectional Matrix

43. Sectional Matrix

44. https://www.youtube.com/watch?feature=player_detailpage&v=WMNmt-eKz1s