Comparative evaluation of the postbleaching application of sodium ascorbate, alpha‐tocopherol, and quercetin on shear bond strength of composite resin to enamel

OBJECTIVE: This study aimed to evaluate and compare the impacts of the postbleaching application of sodium ascorbate, alpha‐tocopherol, and quercetin on the shear bond strength (SBS) of composite resin. MATERIAL AND METHODS: 60 extracted intact maxillary first premolars were collected and were randomly divided into five experimental groups as follows (n=12): Group A (negative control): no bleaching, Group B (positive control): bleaching with 40% hydrogen peroxide (HP), Group C: HP±10% sodium ascorbate for 10min, Group D: HP±10% alpha‐tocopherol for 10min, and Group E: HP±1% quercetin for 10min. Composite bonding was done immediately after bleaching for Groups B‐E and without any treatment for Group A. After being stored in distilled water at room temperature for 24h, all specimens were tested for SBS in the universal testing machine. One‐way analysis of variance and Tukey's post‐hoc test were used to analyze the SBS values of all groups. RESULTS: The results showed that the bonding of composite to the unbleached group exhibited the highest mean value of SBS (22.68±2.91MPa). Among the antioxidant‐treated groups, the highest SBS value was detected in quercetin‐treated specimens (15.45±1.58MPa), which was significantly different from the positive control group (p<.05). CONCLUSION: It could be concluded that 10% quercetin applied for 10min increased the bond strength to bleached enamel, but it was not able to reverse it completely.