Matrix Bands

What is a Matrix Band ?
Types of matrix bands.
characteristics of a good matrix.
Functions.
uses of matrix bands.
Toffelmire, Ivory #1 & #8 matrix band.
Wedges
Role of a wedge.
Modification of a wedge.
Conclusion.

1. 1 Matrices in Operative Dentistry

2. 2 Matrix ? A matrix is d evice that is applied to a prepared tooth before the insertion of a restorative material to assist in the development of the appropriate axial tooth contours and in order to confine the restorative material excess.

3. Clinical Note: The matrix usually is applied and stabilized with a wedge before application of the restorative material

4. Why do we need matrices ? 4  Gingival floor of a class II cavity is the most vulnerable area where overhang of restorative material can take place.  There is no method to control the placement and contour of restoration without a matrix wall.

5. Characteristics of a good matrix 5 Rigidity. Establishment of proper anatomical contour. Restoration of correct proximal contact relation . Easy adaptation to the tooth. Ability to be contoured. Prevention of gingival excess. Strength to offer resistance to condensation. P ressure during restoration . Easy of removal .

6. Functions of matrix 6 Provision of a temporary wall of resistance to the pressure necessary for amalgam insertion. Provision of shape and contour to the restoration. Maintenance of form during placement and set of the amalgam/composite.

7. Classification 7 On the basis of mode of retention. With retainer. E.g. toffelmire matrix Without retainer. E.g automatrix On the basis of type of band. M etallic non transparent matrix Non metallic transparent matrix

8. On the basis of type of cavity for which it is used. Class 1 cavity prep. Double banded tofflemire ( barton matrix) Class 2 cavity prep. Single banded tofflemire matrix Ivory matrix no. 1 Ivory matrix no. 8 Class 3 cavity prep. Mylar strip matrix S-shaped matrix

9. Class 4 cavity prep. Custom lingual matrix Mylar strip matrix Modified s-shaped band matrix Class 5 cavity prep. Window matrix Cervical matrix

10. Metallic matrices 10 I v o r y t y p e T o f fl e m i r e t y p e T- band (straight) Curved T- Band

11. Tofflemire matrix band 11 Also called as Universal Matrix The Tofflemire matrix assembly consists of the following: Matrix bands Matrix retainer Wedge

12. Indications: Tofflemire matrix is ideally indicated when three surfaces (i.e. mesial, distal and occlusal) of a posterior tooth have been prepared It also is commonly used for the two surface class 2 restoration.

13. Advantages: May be positioned on facial and lingual aspect of the tooth. The retainer and band are generally stable when placed. The retainer is separated easily from the band. Matrix bands of various occlusogingival width are available. A small Tofflemire retainer is available for use with primary dentition. When cotton roll isolation is used, The tofflemire retainer holds the cotton roll in place

14. Types of Bands: 14 The non-contoured bands are available in two thicknesses, 0.05mm and 0.038mm. Pre c ontoured matrices may have variable dimensions (depending upon the commercial product ).

15. Advantages of pre-contoured bands over non-contoured bands is they need little or no adjustment before being placed in the retainer or after being positioned around the tooth . Require less chair time. Disadvantage : Expensive

16. Matrix bands • . 16

17. Assembled bands 17 Fig 12-6

18. Clinical Technique 18 Shaping the matrix The flat tofflemire matrix band must be shaped (burnished) to achieve proper contour and contact Burnishing must occur in areas corresponding to the proximal surfaces to be restored. The no.26-28 burnisher is generally recommended for burnishing the band. The band should be placed on a resilient paper pad.

19. The smaller round burnisher tip should be used initially with firm pressure in back and forth and overlapping strokes along the length of the band. This is done until the band is deformed occluso-gingivally . The larger burnisher is then used to smoothen the surface of the band contour.

20. Preparing the retainer to receive the band Step 1: The larger of the knurled nuts is turned counter clockwise. Step 2: while holding the large nut, turn the small knurled nut counter-clockwise. Step 3: the matrix band is folded end to end producing smaller circumference on the gingival end than the occlusal surface.

21. Step 4: the band is positioned in the retainer so that the slotted side of the retainer is directed gingivally to permit easy separation of retainer from the band in an occlusal direction Step 5:The band is placed in the slot and the smaller of the knurled nuts is turned clockwise to tighten the band.

22. Assembly of tofflemire retainer 24

23. Technique 25

24. Placing the band with retainer on the prepared tooth. Step 1: The matrix band is fitted around the tooth (gingival edge of the band is positioned 1mm apical to the gingival margin) Step 2: The larger knurled nut is rotated clock-wise to tighten the band slightly. Step 3: All aspects of the band are assessed. Final corrections are made after wedging. Note: the matrix band should touch the adjacent contact area.

25. Technique 27

26. Removal of the band with retainer Step 1: The small knurled nut is rotated counter-clockwise Step 2: The matrix is removed after hardening of the amalgam to avoid fracture of the marginal ridge during band removal. Step 3: The band is pushed or pulled in the linguo -occlusal direction and if possible, in the direction of wedge insertion. A straight occlusal direction should be avoided. Step 4: The wedge is removed after separating the matrix band from the tooth.

27. W e dges 29  Anatomical (triangular wedges) are recommended for deeper and / or wider proximal preparations.  Rounded wedges are recommended for shallower and / or narrower proximal preparations .

28. W e dges 30

29. Role of wedge 31 It should hold the matrix band firmly in position cervically. It should not be of such a height that it prevents the formation of a contact point. Another function is to separate the teeth slightly so that when it and the matrix are finally removed, the teeth return to their original positions, closing the small space left by the thickness of the matrix band.

30. Modification of matrices 32 All matrices require modification when: proximal surface is a guide plane for tooth/ tissue supported partial denture. Adjacent tooth has a flatter contact. Adjacent proximal contours are not normal.

31. Automatrix Narrow regular (4.7mm), (0.05mm) Wide regular (7.9mm), (0.05mm) Medium thin (6.2mm), (0.038mm) Medium regular (6.2mm), (0.05mm) 33  It’s a retainer less matrix system with four types of bands, designed to fit all teeth regardless of circumference.    

32. P r e f o rm e d Ma t r i x B a nd s 34

33. Are matrices reusable ?? 35 . Re-use of matrix bands is common. Guidelines for the safe re-use of matrix bands are required .

34. Conclusion 36 The role of matrices in operative dentistry is irreplaceable. Without a matrix there is no other way (in a directly placed restoration) to produce contours and contacts. No matrix band is ideal, almost all proximal cavities need a matrix depending on the requirements of the specific case.

35. Thank You…