The influence of different placement techniques on the clinical success of bulk-fill resin composites placed in Class II cavities: a 4-year randomized controlled clinical study

Objective The purpose of this double-blind and split-mouth randomized controlled clinical trial was to evaluate the clinical success of the placement technique (bulk-filling and incremental techniques) of a bulk-fill resin composite in Class II carious lesions. Materials and methods Two different bulk-fill resin composites, X-tra fil (Voco) and Filtek Bulk Fill (3M ESPE), were used in the bulk-filling and incremental techniques for 20 patients. The study was carried out in 4 groups, with 20 restorations in each group. Restorations were appraised at baseline, 6-month, 2-year, and 4-year recall. World Dental Federation (FDI) and the US Public Health Service (USPHS) criteria were used in the evaluations. The Friedman, Kruskal–Wallis, and Mann–Whitney U tests were used for the statistical analysis. Results At the end of year 4, there was no loss of restoration in any group. According to the USPHS and FDI criteria, there was a difference in the baseline and 4-year in marginal adaptation and marginal discoloration of the restorations ( P 0.05). In addition, Filtek-Bulk showed a color change according to the results based on both the USPHS and FDI criteria ( P