A recent question that I received via Facebook asked if I had a technique for making Class Four composites on anterior teeth less challenging. In order to achieve the esthetic results I strive for and my patients count on, I layer composite when repairing a class four fracture. Much like my technician does when layering porcelain, this technique mimics the layers of the tooth, each with different light characteristics and color properties. The challenge whenever we place a class four is free hand sculpting the layers, and then shaping the composite to create a natural tooth form. I have come to depend on silicone matrices as the key to making this easier and more predictable.
How we create the matrix, often depends on the context of the procedure. In some cases we have an existing composite that is being replaced because of marginal breakdown or color change. If I and the patient are happy with the incisal edge position, occlusion and contours, all I have to do is duplicate it with new restorative material. In this case I could fabricate a silicone matrix directly in the mouth, I find this can be very difficult. I prefer to take a quick sectional alginate and create a model either with snap set stone or Mach II die silicone. Now I can create an incisal guide matrix from Flexitime Easy Putty. This process can be done ahead of the appointment or in truth the day we have the composite scheduled. I find the ten minutes it takes from alginate to matrix, saves me far more then that in trimming and shaping in the mouth.
If we are planning to change the occlusion, incisal edge position or lingual contour of the tooth before placing the new composite we need this accomplished prior to making the matrix. I can spend a few minutes in the mouth making these changes prior to taking the alginate, or make the changes on the model before I form the matrix. Often I am making major changes to the tooth, as the patient has shown up having just fractured off the corner of their tooth. If the tooth is stable and I feel like we can move ahead with a final restoration, I use the above technique and replace the missing corner on the model as a guide so I can be efficient and effective in the mouth.
The matrix needs to capture the lingual and interproximal contours, and wrap to the facial side of the incisal edge. For stability I wrap the putty over the occlusal of the premolars, so I have a positive seat when placed in the mouth. After I have confirmed the matrix fits, I prepare the tooth. The next step is to etch and apply dentin adhesive. When I am ready to begin placing composite, the first layer will be the lingual wall. I use my enamel shade and actually place this on the matrix in the proper thickness, making sure to extend slightly more apical then the margin. Next I seat the matrix in the mouth and light cure this first layer. I now have a lingual wall of composite that has created the lingual contour, incisal edge and interproximal form. The rest is simple, stack composite moving facially, to create your esthetic layers.