Bulk-fill Composite Restoration Efficacy

The average of annual failure rate of bulk-fill composite resin restorations in randomized clinical trials was 2.5%.^{6 (link) , 26 (link)} Therefore, the overall success rate of bulk-fill composite restorations would be approximately 95% after two years of clinical service. With an α of 0.05, a power of 90%, and a two-sided test, the minimal sample size was 44 restorations in each group to detect a difference of 25% between groups. However, considering the risk of patient losses intrinsic to randomized clinical trials, we chose to increase the number of restorations in each group by 20%. Thus, 53 cavities per group were included. These calculations were performed at www.sealedenvelope.com for one of the researchers (A.L.).