effect of thermocycling and type of restorative material on microleakage of class ii restorations

objectives: microleakage is a major cause of failure of dental restorations and results in development of secondary caries, tooth hypersensitivity and pulp pathosis. this study aimed to compare the microleakage of class ii cavities filled with two types of composite resins and a compomer and subjected to thermocycling. methods: in this in vitro experimental study, class ii cavities with a gingival margin below the cementoenamel junction (cej) and beveled enamel margins were prepared in proximal surfaces of 60 molar teeth. the teeth were randomly divided into three groups of 20 and restored with spectrum tph3 and esthet x composites and dyract extra compomer. each group was randomly divided into two subgroups (n=10) of control and thermocycling (1000 thermal cycles). dye penetration in occlusal and cervical margins was scored under a stereomicroscope. data were analyzed using the kruskal wallis test and mann whitney u test (p<0.05). results: no significant difference was noted in microleakage of the three groups neither in the occlusal nor in the cervical margins in presence or absence of thermocycling (p>0.05). but, the microleakage in the cervical margins of compomer restorations was slightly higher than that of other groups especially after thermocycling. conclusion: microleakage of composite restorations was not significantly different from that of compomer restorations in the occlusal or gingival margins in presence or absence of thermocycling