Observations on a composite resin for Class II restorations: Two-year report

Abstract

A clinical study was conducted to compare the performance of a commercial composite direct-filling resin with that of amalgam in Class II cavities. Of 124 paired restorations placed in 73 patients, 92 pairs were available at the two-year period. The restorations were subsequently evaluated at one and two years by a team of examiners from the Materials and Technology Branch of the Division of Dental Health, United States Public Health Service, San Francisco. Caries was not detected with either material during the two year period. No gross fractures occurred in the composite resin restorations. Three amalgam restorations fractured during the first year, and one amalgam restoration was replaced at the time of the second examination because of suspected, although not confirmed, fracture. At the end of two years, a number of restorations of each material exhibited some degree of marginal breakdown. Amalgam restorations had little or no change in anatomic form, while a moderate change was observed in approximately one half of the composite resin restorations. The change in anatomic form appeared to be the result of occlusal wear. Until formulations are improved in this respect, the use of composite systems in Class II restorations should probably be limited to those situations where esthetics is the major consideration and the cavity preparations are conservative. Composite restorations were also evaluated with respect to color match and cavosurface marginal discoloration. A change in color match was observed in approximately 60 per cent of the composite resin restorations with time. However, the change appeared to be due to surface stain rather than color shift of the material. Slight marginal discoloration was detected in approximately 70 per cent of the composite restorations.