Occlusal loading evaluation in the cervical integrity of Class II cavities filled with composite.

There are many doubts about the clinical behavior of condensable composite restorations in Class II cavities, particularly when they are submitted to axial mechanical loads. This study evaluated cervical microleakage in Class II direct fillings in composite, whether or not they were submitted to an occlusal load cycling. Twenty-three human molars with standardized cavities (proximal vertical "slot") were treated with enamel and cement endings. After completion of the filling process with condensable composite (Surefil), they were separated into two groups: control (without occlusal loading) and test, where 4,000 one-second cycles of 150 N occlusal loading were applied. Twenty teeth were submitted to a microleakage test and then evaluated according to dye penetration. Significant statistical differences (Wilcoxon test, p=0.005<0.05) of leakage degree in enamel and cement were found in the control group. Significant statistical differences at <0.05 were also found in the test group, with p=0.045. After paired comparison of the control and test groups, a significant statistical difference was found at the enamel level (Mann-Whitney test, p=0.03). However, no significant statistical differences were found at the cement level (p=0.28). Therefore, it could be concluded that there was greater microleakage in cement compared to enamel, and occlusal loading has a decisive influence, as it increases the rate of microleakage.