Poor bonding stability remains the "Achilles' heel" of dentin bonding, a simple and effective approach to 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.

No abstract

The purpose of this study was to evaluate the capability and characteristics of different nanoleakage observation methods, including light microscope (LM), field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and confocal laser scanning microscope (CLSM). Dentin specimens were bonded with either an etch-and-rinse adhesive (SBMP) or a self-etch adhesive (GB), and prepared for nanoleakge evaluation according to different observation methods. LM, FESEM and CLSM results demonstrated that the SBMP group showed more interfacial nanoleakage than the GB group (p<0.05); by contrast, no significant difference was found in TEM results (p>0.05), however, TEM illustrated concrete nanoleakage forms or patterns. The results suggested that different observation methods might exhibit distinct images and a certain degree of variations in nanoleakage statistical results. Researchers should carefully design and calculate the optimum assembly in combination with qualitative and quantitative approaches to obtain objective and accurate nanoleakage evaluation.

No abstract