Effects of the removal of composite resin restorations on Class II cavities

Composite resin has such good aesthetic qualities that it is often difficult to identify the tooth-restoration interface, yet this is particularly important should the material require complete removal. Following the in-vitro removal of direct and indirect composite resin restorations from Class II cavities significant changes in cavity size and shape were recorded. Thirty-eight cavities were studied from both occlusal and proximal aspects and the final cavity size was compared to the original cavity. There was a significant increase in cavity size with a mean increase of 37% for the direct composite cavities and 35% for the indirect cavities, although the range of values is large. Following restoration removal, occlusal surfaces were seen to increase in 71% of teeth and proximal surfaces in 75% of teeth. There was no significant difference between the results for direct and indirect composite restorations. Occlusal dovetails and cavity undercuts were created in cavities which did not contain these features initially.