Marginal leakage of microfilled composite resin restorations

Abstract

I nvestigations have shown that marginal leakage is significantly reduced or eliminated in restorations where the cavosurface angle and the enamel are etched and a layer of unfilled resin is placed before and after placement of the restoration.‘-6 -Elimination or reduction of marginal leakage would decrease sensitivity, discoloration, and recurrent caries and thereby result in greater longevity of composite resin restorations.’ Recently, composite resins of different compositions have been introduced to the dental profession. They are known as microfilled composite resins and are designed to give smooth textures of the surface after finishing procedures. The microfilled composite resins have a higher coefficient of thermal expansion than tooth structure and conventional composite resins. Thermal dimensional changes in composite restorations depend on the coefficient of thermal expansion of the composite resins and the size of the restoration. Apparently, to minimize marginal leakage and to maintain marginal integrity, the thermal expansion of composite resin restorations should be similar to that of tooth structure.* This study evaluated the marginal leakage of several microfilled composite resins that have higher coefficients of thermal expansion than tooth structure or the conventional composite resins.