Introduction: Simultaneous etching of enamel and dentin using the novel generation of adhesive systems with contracted operational steps, has shown a good clinical efficacy. The aim of this study was to evaluate the microleakage of composite restorations using the V and VII generations of adhesive systems on primary teeth.

Methods: This study was performed on 45 human intact extracted primary teeth. Following class V cavity preparation, the samples were randomly divided into three groups included 15 teeth based on the type of bonding agent Single Bond 2, Clearfil S3 Bond or G Bond. After applying the bonding agents, the teeth filled with composite Z250. The microleakage values of incisal and gingival margins were separately scored by 2% basic fuchsine staining based on a 0-3 ordinal ranking system. The data were analyzed by using Kruskal Wallis and Mann_whitney U tests.

Results: In overall, the score of microleakage at incisal (0.58±0.94) and gingival (1.06±0.19) edges did not have significant difference. Also, there was no significant difference between incisal and gingival microleakage considering the different types of bonding.

Conclusion: Regarding to less operational steps and lower risk of salivary contamination, the VII generation of dentin bonding agents can be applied for filling the class V cavities of primary teeth.