Use of Composite Restoration Materials

Introduction Approximately 27 % of dogs and 10 % of cats presented for veterinary care may have fractured teeth. Abrasion and attrition are also common causes of dentinal exposure. Fractures of the teeth are classified as complicated or uncomplicated. Complicated crown fractures extend into, or involve the pulp chamber or root canal system. They must be treated with endodontic or exodontic therapy. Uncomplicated fractures involve enamel and the underlying dentin, but do not result in pulp exposure. Uncomplicated fractures of vital teeth, in the absence of endodontic disease, may be treated with a bonded sealant and additional restoration with a resin composite. Composite restoration should only be performed in vital teeth with no exposure of the root canal system and no radiographic evidence of endodontic involvement. Restoration should result in a pain-free, functional, esthetic tooth that resembles the normal, healthy tooth. It should also be able to withstand normal occlusal forces and retain natural tooth structure as much as possible. This article reviews proper decision-making in treatment of uncomplicated crown fractures to reinforce the reader’s knowledge of the basics of restorative materials and their application. Oral examination, dental charting, and dental radiographs are completed with the patient anesthetized prior to any restorative treatment. The teeth are scaled supraand subgingivally using a water-cooled, ultrasonic scaler and polished with a nonfluoride prophylaxis material (Fig.1). The polishing material should be free of glycerin and fluoride so it will not interfere with chemical bonding. The steps in restoration include shaping and contouring the fracture edges, acid-etching, placing a lightcured bonded sealant and resin composite, and final shaping and finishing. Cavity preparation or shaping is performed according to the G.V. Black classification of cavities and restorations. The preservation of natural tooth structure is the most important rule of restorative dentistry. Dentin, pulp, and periodontal tissues should be retained as much as possible. Preparation of the tooth using the sequence outlined by Black resistance, retention, convenience, pathology removal, wall, and preparation cleansing forms uses biological mechanical principles. Beveling of the tooth’s cavosurface margins in class III-VI restorations provides greater retention strength due to greater enamel surface area and improves esthetics, due to the gradual transition from composite to enamel. Beveling of occlusal cavosurfaces in class I or II preparations is contraindicated, because it enlarges the surface area of the restorative in occlusion. Also, composite restorations are not as strong as enamel and wear faster. The thinner areas of composite along the marginal aspect are more prone to fracture from occlusal stress that can cause marginal leakage in the restoration. Therefore, the cavity preparation should always maintain the enamel margin. A hand curette is used to initially smooth and remove all unsupported enamel rods or undercuts secondary to pathology. A round-taper fine diamond bur on a high-speed handpiece removes rough edges of the fractured dentin and any unsupported enamel for marginal adaptation. A conical Arkansas whitestone bur on a low-speed handpiece followed by sanding discs may be used to further smooth the fractured dentin and enamel (Fig. 2). Other options for cavity preparation include the use of a carbide bur and progressive grades of shaping discs from coarse Ellen D. Domnick, DVM