Effects of hydrogen peroxide present in mouthwashes on bonding efficacy of universal adhesives to dentin surface

AbstractBackground:To evaluate the effects of the repeated use of hydrogen peroxide (HP)-based mouthwashes on the bonding efficacy of universal adhesives for bonding to dentin surfaces.Methods:In this study, 384 human third molars were divided into 48 experimental groups according to the application of two HP-based mouthwashes for 1, 7, 15, and 30 days. The adhesives included Scotchbond Universal and Ambar Universal adhesives, and the adhesive strategies were etch-and-rinse and self-etch. Additionally, for each mouthwash protocol, one group without mouthwash and another group which underwent in-office bleaching were used as positive and negative controls, respectively. Teeth were treated separately in each mouthwash protocol, and after that, they were restored and tested for their microtensile bond strength (µTBS), nanoleakage (NL), and degree of conversion (DC). The data were subjected to a three-way analysis of variance (ANOVA) and Tukey's test (α = 0.05) for each evaluated property.Results:A significant decrease in the µTBS was observed for both mouthwashes (15 and 30) relative to the negative control group (p = 0.0001). However, both groups showed higher µTBS values than those for the in-office bleaching group (p < 0.0001).Regarding the NL, a significant decrease in the NL values was observed for both mouthwashes (30) when compared to the negative control group (p < 0.01). Moreover, both mouthwash (15 and 30) groups showed lower NL to dentin values when compared to in-office bleaching (p < 0.01).Conclusion:Even at low concentrations, the continuous and prolonged use of an HP-based mouthwash affects the µTBS and DC values, and leads to an increase in the NL of the universal adhesives in the dentin.