In vitro evaluation of microleakage in posterior composite restorations

Objectives: The aim of the present study was to examine the effects of different placement techniques on the microleakage and marginal adaptation of composite restorations. Methods: Class II inlay cavities were prepared on 100 extracted human molar teeth. In the first group, composite restorations were made incrementally with two different composite resins. The second group comprised direct inlays made with the same restoratives while, in the third group, indirect inlays were made. The second photopolymerization of the inlays were accomplished with a light box and they were luted. In the fourth group, composite restorations were made by using ceramic inserts. In the fifth group, restorations were made by applying pressure with occlusal compressors on the composite resin systems with ceramic inserts. All samples were thermocycled and kept in 0.5% basic fuchsin. The samples were sectioned longitudinally and examined by a stereomicroscope for microleakage. In each group, one specimen was selected randomly to examine the marginal adaptation of the restorations using a scanning electron microscope. The results were statistically analyzed with Kruskal Wallis and Mann-Whitney U tests. Results: No statistically significant differences were found in the occlusal microleakage scores among all groups (p=0.05), although no microleakage was observed in the fifth group. The gingival microleakage scores of the first and second groups were higher than all groups and statistically significant differences were found between those of the fourth and fifth groups (p<0.05). Although statistically insignificant, the gingival microleakage scores of the fifth and third groups were less than fourth and second groups, respectively (p=0.05). A perfect adaptation was investigated in SEM analysis in both the gingival and occlusal area of the fifth group. Conclusion: Using ceramic inserts with composite resin systems and applying pressure with occlusal compressors during polymerization were found to be effective to decrease the microleakage.