To determine the effect of bleaching agents on the plane strain fracture toughness of composite materials under various experimental conditions.
Four nanofilled epoxy resin composites-Filtek Supreme Plus, Tetric EvoCeram, Premise, and Esthet-X were evaluated. Four concentrations of bleaching agents were tested: Opalescence PF 10, 20, 35 and 45%. Fifty specimens of each composite, conforming to ASTM guidelines for single-edge notch bar-shaped specimens, were fabricated using a metal mold. All specimens were stored in artificial saliva at 37 °C for at least 24 h before exposure to bleaching agents. Ten specimens of each material served as controls, while the remaining 40 were evenly divided into four groups for bleaching agent application (n = 10). The epoxy resin composites were bleached on both sides for 14 days. Subsequently, the specimens underwent a three-point bending test at a cross-head speed of 0.2 mm/s. The plane strain fracture toughness (KIc) was then calculated.
The control group KIcvalue for Esthet-X was significantly higher than that of the other composites. Bleaching agents significantly increased the plane strain fracture toughness of Filtek Supreme Plus. However, the application of bleaching agents did not cause significant changes in the fracture toughness values of the other nanofilled epoxy resin composites tested.
The influence of bleaching agents on the plane strain fracture toughness of epoxy resin composites has not been studied previously.
