I must admit that I don't know a lot of dentists who "look forward" to a day filled with posterior Class II resins. These restorations are often technically difficult, time consuming and overall challenging to do well.
The sectional matrix systems have done wonders in helping make it easier to create restorations with better contours and proximal contacts. These systems continued to evolve from the generic BiTine or G-Rings to rings with more proximal contour/anatomy to help better adapt the sectional matrix to the tooth. (Figure 1)
Unfortunately, every tooth has slightly different contours so, although the new rings are helpful, they are often far from ideal. One thing that can be done to help make posterior composites a little easier and more enjoyable is to use a "customized" posterior matrix. The good news is that making the customized matrix is rather quick, and you most likely already have what you need to do it.
This technique was developed by Dr. Jordi Manuata from the group Style Italiano an exquisitely talented clinician. More information can be found by following the links below.
The 6-Step Customized Posterior Matrix Technique
1. Prior to preparing the tooth, pre-wedge and place a small amount of Opal Dam or similar product (e.g. Kool-Dam, Ena-Dam) in the buccal and palatal proximal embrasures and cure. (Figure 2)
2. Using the original BiTine or G-Ring design, place the ring engaging the first increment of Opal Dam (the ring should not bite through the first increment or touch the tooth). Once the ring is in place, completely surround the working end of the ring with more Opal Dam and cure. (Figure 3)
3. The customized matrix is now complete and can be removed from the mouth. The Opal Dam should be one with the ring. (Figure 4)
4. Prepare the tooth and finalize the preparation. Place your sectional matrix/wedge and assure a good seal at the gingival margin. Once complete, place the customized matrix. (Figure 5) Since the matrix was fabricated with a wedge in place, it should fit intimately against the tooth. However, if the wedge is in a slightly different position and doesn't allow the matrix to be seated completely, the apical portion of the custom matrix can be adjusted with a bur outside of the mouth. Note how well the sectional matrix conforms to the contours of the tooth. This will help ensure ideal contours and help minimize the time required for finishing.
5. The tooth is now ready to be selectively etched, bonded and layered with composite. (Figure 6)
6. Once the final contour is built and cured, the matrix can be removed to allow for proper finishing and polishing. The image on the left in Figure 7 was taken immediately after removal of the matrix. Note how well the proximal contours blend with the natural tooth, thereby minimizing the amount of finishing required. The image on the right of Figure 7 is after finishing.
As you can see, this technique is not difficult to perform, but it can have a dramatic impact on the final outcome. In addition, it can be used in a variety of clinical situations where the traditional matrices fall short. However, given that the custom matrix adapts and recreates the contour of the existing tooth, the technique is generally not recommended when you do not desire to reproduce the existing anatomy.
Style Italiano links
(Click this link for more dentistry articles by Dr. Gregg Kinzer.)
Gregg Kinzer, D.D.S., M.S., Spear Faculty and Contributing Author