Effect of bleaching on microleakage of class V composite resin restorations-in vitro study

The purpose of this study is to evaluate the effect of bleaching on microleakage of class V resin composite restorations, both occlusal and gingival margins of enamel. One hundred and twenty-eight class V restorations were performed on buccal and lingual surfaces of 64 premolars. Half of them were restored with Synergy D6 and the other one with Filtek Supreme XTE. In all of them, 5th generation adhesive XP Bond, Dentsply® was used. The teeth were submitted to thermal cycling and then divided into three groups: Group I-no bleaching, group II-bleaching with 38% hydrogen peroxide and group III-bleaching with 10% carbamide peroxide. Immersion was performed with 2% methylene blue dye and microleakage was measured according to ISO standards. Data was analyzed using the chi-square test. When composite restorations were submitted to bleaching, microleakage was only statistically significant on the gingival walls of buccal (r < 0.009) and lingual surfaces (r < 0.002). Bleaching with 38% hydrogen peroxide and 10% carbamide peroxide may increase microleakage on the gingival wall of class V resin composite restorations.