Current Developments in Posterior Composite Resins

Abstract

The use of posterior composite resins has grown at a rapid rate. While the original materials were completely inadequate for the restoration of Class I and II cavity preparations, the newer-generation materials are apparently superior. While wear rates of over 100 μm per year were not uncommon, some of the newer composites wear away at the rate of less than 1 μm per month. A great deal of the improvement in wear resistance can be attributed to an optimization of the filler particle. Specifically, the particle size has been decreased and the filler loading has been increased. In some instances, softer filler particles have been incorporated in order to decrease the hardness differential between the filler and the resin matrix. Other factors which have been considered include chemical erosion of the matrix, degradation of the silane coupling agent, internal porosity, method of polymerization, and hydrophobicity of the resin matrix. A greater understanding has been developed regarding patterns of wear as well as rates of wear. Techniques have been developed for rapid and routine measurements of the loss of anatomical form. Although the composite resins have been improved substantially, their use in posterior teeth is quite technique-sensitive. Furthermore, the problem of secondary caries is still a major concern.