Class III Composite Restorations
These are the major use for composite resins today. Composite resin materials have become the most popular material for Class III, as well as Class IV and Class V, restorations. These cavity classifications are excellent examples of the use of bonding for esthetic superiority as well as its economic pluses. When bonded composite resin restorations are placed, finished, and polished correctly, and a suitable shade of composite resin is used, Class III restorations can simulate perfectly the appearance of natural enamel and they last for many years. Composites come in almost every shade, range, translucency, and opacity. Acid etching seals the composite to the enamel for functional soundness. However, you will need to purchase additional shades from several different manufacturers to cover a complete range of color options. Shade selection for the Class III composite can be both time consuming and frustrating. The major problem is choosing a shade that will actually match after you have inserted and finished the restoration. Typically, the first thing you do is place a sample of the intended material on the tooth to be restored. The difficulty is to anticipate the correct amount of material thickness so the final result will match. A good method of accomplishing this is to vary the thickness of the sample by pressing harder on one end with the mylar strip so you will get a gradation of color and, therefore, get a better indication of just how close your shade will match with the estimated thickness.
The replacement of discolored anterior restorations with composite resin comprises one of the largest percentages of esthetic restorative dentistry.
The basic tooth preparation for the Class III restoration consists of a reverse bevel and an overlaid margin that extends several millimeters past the bevel. This provides extended restoration longevity and a better color blend.
After the old restorative material is removed and a reverse bevel placed.
Acid etching should be accomplished for 15 to 20 seconds depending upon manufacturer’s instructions.
Although 5 to 10 seconds of air/water spray should be sufficient, if the etching medium is a gel, it may take twice as long to completely remove all of the acid.
Use different colored brush handles (Centrix, Shelton, CT) to apply the various agents used in the bonding process. Here a red brush is used to apply the final bonding agent.
Use a gentle stream of air to ensure a thin layer of the bonding agent. Follow this with labial and lingual polymerization of 20 seconds each.
The preselected shade of composite resin is applied with a thin-bonded, nonstick composite instrument in small increments and polymerized layer by layer. To increase depth of color, consider using a slightly darker shade initially followed by a lighter one, rather than one shade for the entire restoration.
The ET6 8-bladed carbide bur gently removes excess composite at the mesiolabial line angle. The ET6F 16-bladed carbide completes gingival contouring. Final labial finishing is done with the ET6UF 30-bladed carbide. The OS1 finishing bur (ET Series, Brasseler) is the perfect shape to do lingual contouring. Cervical, interproximal, and lingual margins are finalized with an ET3 or ET4.