Thirty-six-month clinical evaluation of posterior high-viscosity bulk-fill resin composite restorations in a high caries incidence population: interim results of a randomized clinical trial

Objectives This study compared the clinical performance of two bulk-fill (BF) and one conventional resin composite in a population with a high caries incidence. Materials and methods A total of 138 class I and II restorations were performed and randomly divided into three groups ( n = 46) with equal allocation: Filtek BF (FBF; 3M ESPE), Tetric EvoCeram BF (TBF; Ivoclar Vivadent), and control Filtek Z250 (Z250; 3M ESPE). The evaluations were performed using the USPHS and FDI criteria at baseline and after 12 and 36 months by a previously calibrated evaluator. The Friedman and Wilcoxon tests for paired data were used for statistical analysis ( α = 0.05). Results The DMFT index at baseline was 9.44, with 87% from the decayed component. After 36 months, 108 restorations ( n = 36) were evaluated. Two failures were observed for TBF at marginal adaptation and recurrence of caries, resulting in a survival rate of 94.44% and an annual failure rate (AFR) of 1.26%. No equivalence was observed between the criteria for surface roughness, marginal adaptation, and discoloration. Conclusions The 36-month clinical performance of high-viscosity BF resin composites was comparable to conventional incremental-filled resin composites. The FDI criteria better presented the restorations’ clinical success. However, in the case of failure, both criteria provided the same result. Clinical relevance High-viscosity bulk-fill resin composites showed excellent performance after 36 months in a high caries incidence population. It can be considered a simplified alternative restoration method that reduces operating time and minimizes possible operator errors.