Effect of thermal and mechanical load cycling on the marginal integrity of Class II resin composite restorations.

Class II cavities were prepared in extracted human teeth and adhesively restored with one of three different composite systems. Also, for each system samples were made with a light-cured glass ionomer base. Marginal integrity was measured by dye penetration and SEM observation before and after stressing the samples with thermal and mechanical load cycling. Before loading, the bond system in combination with acid etching the dentin provided superior results. Loading did not significantly affect marginal integrity in light-cured glass ionomer lined samples. This was in contrast to unlined resin dentin bonding system/resin composite restorations where loading did deteriorate marginal integrity significantly.