Comparative evaluation of outcome of natural antioxidants on shear bond strength of composite bonded to bleached enamel: An In vitro study

Background: The depletion of bond strength after the bleaching procedure has resulted in the usage of several antioxidants to get rid of discharging oxygen from residual peroxides before any adhesive restorations. Aim: The in vitro study aimed to compare and evaluate the shear bond strength of composite after application of three over-the-counter natural antioxidants on bleached enamel. Materials and Methods: Thirty-six extracted human anterior teeth were decoronated at the level of cementoenamel junction and implanted into self-cure acrylic resin exposing the labial surface alone. The embedded specimens were categorized into six groups of six teeth each, and the groups were as follows: Group I: unbleached + composite bonding, Group II: bleaching + delayed composite bonding, Groups III, IV, and V: bleaching + antioxidants - olive oil/Vitamin E oil/propolis + immediate composite bonding, and Group VI: bleaching + immediate composite bonding. The shear bond strength analysis was performed with the help of the universal testing machine, and the values obtained were statistically analyzed using IBM SPSS for Windows, v. 21.0. Results: The results obtained from the study reveal that all the three experimental groups showed an increase in the shear bond strength in comparison to Group VI (positive control) and the difference in the bond strength between the experimental groups and positive control is also statistically significant. Conclusion: Within the limitations of this study, although the bond strength of composite resin after application of the three natural over-the-counter antioxidants falls very closely, the usage of oil-based antioxidants had been found to perform less effectively in improving the shear bond strength.