Quercetin as a simple but versatile primer in dentin bonding

Poor bonding stability remains the “Achilles' heel”of dentin bonding, a simple and effective approachto inhibit the activities of both exogenous collagenases and endogenous MMPs, and prevention of the growth of bacterial biofilm is therefore highly demanded. In the present study, a quercetin/ethanol solution was developed as a multifunctional primer to pretreat the dentin surface during adhesive restoration. The results showed that pretreatment with quercetin/ethanol solutions (0.5 and 1.0 wt%) on the dentin surface effectively preserved the bonding strength after one-month of collagenase aging (p< 0.05). Irrespective of aging, lower nanoleakage expression and less cohesive failure in dentin were observed in the quercetin-treated groups (p< 0.05). Compared with the control group, the in situ zymography test revealed that the 0.5 and 1.0 wt% quercetin-treated dentin effectively inhibited MMP activity, while their contact angles significantly increased. Live/dead bacterial staining and the MTT assay demonstrated that the 0.5 and 1.0 wt% quercetin groups exerted significant bactericidal effects while inhibiting biofilm growth of Streptococcus mutans (p <0.05). We believe that a quercetin/ethanol solution might serve as a simple but versatile primer to provide dentists with a promising approach to obtain desirable bonding stability and to prevent secondary caries, thereby preventing the frequent replacement of resin-based restorations.