A clinical study on direct and indirect Class II posterior composite resin restorations: design of the investigation.

The combination of composite resins with adhesive intermediate agents and techniques is still questionable with respect to application to posterior regions of the dentition. To add data to the information already available about the clinical behavior and longevity of class II composite resin restorations, a longitudinal study has been started; its design is discussed in this paper.

Marginal integrity related to bond strength and strain capacity of composite resin restorative systems.

The shear strength of composite resin restorative systems bonded to dentin was measured and marginal integrity of class V restorations was assessed. A correlation between bond strength and marginal adaptation could not be demonstrated. The application of an intermediate layer of unfilled resin or the use of low-stiffness composite resins to improve the strain capacity of the restoration significantly influenced the quality of the marginal integrity.

Complete marginal seal of Class V resin composite restorations effected by increased flexibility.

The use of adhesive resin composites for restoration of Class V lesions often results in cervical marginal gap formation due to polymerization contraction. In this laboratory study, flexible linings applied between the bonding agent and the bulk restorative appeared to preserve the marginal integrity of Class V restorations during curing. Measurements of the polymerization contraction stress showed 20 to 50% relief due to various flexible intermediate materials.