Effect of restorative timing on shear bond strength of composite resin/calcium silicate–based cements adhesive interfaces

Objectives The aim of this study was to evaluate the shear bond strength inherent to immediate and delayed definitive composite resin restorations, over three different biomaterials. Methods Fifty-four aluminum blocks were randomly assigned to six experimental groups ( n = 9) according to the biomaterial (Biodentine, TotalFill BC Putty, or PCM) and restoration timing (immediate or 7 days delayed). Regarding the restorative procedures, a two-step self-etch bonding system (Clearfil SE Bond) was applied and subsequently restored using a flowable composite resin (SDR). After shear bond strength testing, fracture pattern analysis was performed. The significance level was set at α = 0.05. Results Within the immediate groups, Biodentine showed the highest mean shear bond strength value, with no statistically significant differences ( P > 0.05) being detected when compared with both TotalFill ( P = 0.072) and PCM ( P = 0.232) groups. Regarding the delayed restoration groups, Biodentine and TotalFill presented the highest mean shear bond strength value, with statistical differences when compared with PCM ( P = 0.002 and P = 0.043, respectively). No statistically significant differences ( P > 0.05) were verified between both immediate and delayed groups for each tested biomaterial. Also, a statistically significant association was found between the fracture type and the biomaterial ( P < 0.001). Conclusions and clinical relevance Our findings suggest that all tested biomaterials present suitable alternatives which allow to perform restorative procedures immediately after pulp capping biomaterial placement (3 or 12 min, depending on the bioactive cement), therefore requiring one single appointment to complete the procedure. Biodentine and TotalFill BC Putty have shown superior shear bond strength results when compared with PCM, within a delayed timeframe (7 days).