Sealing ability of eight resin bonding systems in a Class II restoration after mechanical fatiguing

The purpose of this in vitro study was to evaluate eight different adhesive systems to determine whether functional loading affects the marginal integrity of Class II restorations. In 80 extracted upper human premolars, Class II cavities were prepared and restored with eight different commercially available adhesive resin restorative systems. The occlusal margins were located in enamel and the gingival margins in dentin. During immersion in a dye solution, half of the restored teeth were exposed to a load-cycling procedure, after which all the specimens were sectioned, and the extent of dye penetration was visually examined using a stereo microscope. The results were analyzed statistically using the Mann-Whitney U-test and Wilcoxons Rank test. Exposure of the restorations to load cycling significantly reduced the marginal integrity cervically. Perfect sealing was found practically at all occlusal margins. Significant differences (p < 0.05) were found in the cervical sealing quality of the various adhesive systems. The results of this study show that functional loading damages the cervical marginal seal of adhesive Class II restorations. For many adhesive systems, the setting shrinkage stress alone was not able to damage the marginal integrity cervically. Therefore, mechanical fatiguing distinguishes the sealing quality of adhesive systems in a more expressive way. There is a substantial difference in sealing quality between the various resin restorative systems tested.