In-Vitro Evaluation of the Effect of PH on the Flexural Strength of Bulk-Fill and Conventional Composite

Bulk-fill composites were introduced to reduce the number of clinical stages and the technique sensitivity of composite restorations. This study aimed to determine the effect of PH on the flexural strength of bulk-fill and conventional resin-based composites (RBCs). In this in vitro study, one bulk-fill RBC (Tetric N Ceram Bulk-Fill [TNCBF]) and one conventional RBC (Tetric N Ceram [TNC]) were used. Thirty-six samples were prepared and divided into six groups (n=6), according to the type of RBC and the PH of the storage solution (7, 5, and 2.5). Specimens were stored in the designated solutions for 30 days at 37°C. Their flexural strength was then measured using a universal testing machine. One-Way ANOVA and post hoc Tukey’s test were used to analyze data at the significance level of P<0.05. Conventional RBCs showed a significantly higher flexural strength than bulk-fill RBCs (P=0.02). On the other hand, the PH of the solution had no significant effect on the flexural strength (P=0.11). Considering the limitations of laboratory studies, it can be concluded that the PH of the solution does not affect the flexural strength of composites. Although the flexural strength of TNC is higher than that of TNCBF, both are within the clinically acceptable range.