Use of polyphenols as a strategy to prevent bond degradation in the dentin–resin interface

This study evaluated the effect of dentin pretreatment with the polyphenols quercetin and resveratrol on the resin-dentin microtensile bonding strength (μTBS) and collagen fibrils stability of the adhesive interface. Different concentrations (100, 250, 500, or 1,000 μg ml-1 ) of quercetin or resveratrol, or a mixture of quercetin and resveratrol (3:1, 1:1, 1:3; vol:vol), as well as distilled water or 2% chlorhexidine digluconate, were applied to etched dentin. Then, a two-step etch-and-rinse adhesive was applied followed by composite restoration. Measurements of resin-dentin μTBS were made after 1 and 120 d. The stability of collagen fibrils in the hybrid layer was evaluated using transmission electron microscopy. The Student's t-test and two-way factorial anova with Tukey's test were used to analyze the effects of dentin pretreatment and storage time on μTBS values. Comparisons between μTBS measurements made on 1 and 120 d showed that resveratrol had the best performance, with significantly higher μTBS values after 120 d for all concentrations of resveratrol tested. Quercetin pretreatment resulted in a significant rise of μTBS when used at concentrations of 100 and 500 μg ml-1 . Quercetin + resveratrol at the ratio of 1:1 performed better than when used at ratios of either 3:1 or 1:3. Resveratrol might represent a potential approach to achieve desirable bonding stability and reduce the frequent replacement of composite restorations.