Objective: This study evaluated the effect of additional enamel etching on the clinical performance of Class III composite restorations bonded with a mild two-step self-etch adhesive system in a three-year evaluation of clinical service.
Methods: Using a paired-tooth study design, 38 patients received at least one pair of restorations. In each paired cavity, a mild two-step self-etch adhesive (Clearfil SE Bond) was used, either with (C-SE etch) or without additional enamel etching, using phosphoric acid (C-SE non-etch). Clearfil AP-X was used as the restorative material for all restorations. Evaluation of the restorations was performed at baseline and after six months, one year, two years and three years of clinical service in terms of retention, marginal discoloration, marginal adaptation, postoperative sensitivity and secondary caries using the modified Ryge criteria.
Results: A retention rate of 100% both for the C-SE non-etch and C-SE etch groups was noted. Significant differences were observed between the groups regarding the marginal discoloration (p = 0.001) and marginal adaptation (p = 0.002) at three years. C-SE non-etch restorations revealed more small marginal defects and superficial marginal discoloration than the C-SE etch group.
Conclusion: Although the clinical performance of the mild two-step self-etch adhesive in Class III cavities was found acceptable after three years, additional etching of the enamel margins improved the marginal quality of this adhesive by preventing small marginal defects and superficial marginal discolorations.