microleakage of composite resin restorations using a type of fifth and two types of seventh generations of adhesive systems: a comparative study

introduction: in recent dentin adhesive systems etching of enamel/dentin are achieved simultaneously. the objective was to evaluate the microleakage of composite restorations using single bond2 (5th generation), clearfil s3 bond and g bond (7th generation). methods: class v cavities were prepared on  45 extracted intact premolars with gingival margins at the cementoenamel junction and they were randomly divided into 3 groups (n=15) based on the type of adhesives: single bond2 (5th generation), clearfil s3 bond and g bond (7th generation). after applying the adhesives, the cavities were filled with z250 composite resin. the occlusal and gingival microleakage was evaluated using 2% basic fuchsin staining technique. data were analyzed using kruskal-wallis and bonferroni corrected mann-whitney u tests. results: the mean rank of occlusal microleakage exhibited significant differences by comparison of g bond, clearfil s3 bond and single bond2 (21.07, 30.67) and 17.27, respectively) (p=0.005). there was a significant difference in gingival microleakage of different bonding agents (34.40, 17.83 and 16.77 for g bond, clearfil s3 bond and single bond2, respectively) (p< 0.001). there was a significant difference in occlusal microleakage of clearfil s3 bond and single bond2 (p= 0.003), but no significant difference was found between clearfil s3 bond and g bond (p=0.025). no significant difference was observed between occlusal microleakage by g bond and single bond2 (p=0.238). the difference in gingival microleakage was significant by g bond compare with single bond2 and clearfil s3 bond (p< 0.001and p< 0.001, respectively). conclusion: the microleakage of class v composite restorations in permanent teeth using the single bond2 was lower than that with the use of g bond in gingival margins. the sealing ability with single bond2 was superior to clearfil s3 bond in occlusal margin but they were equally effective at gingival margin.