Effect of Baicalein on Matrix Metalloproteinases and Durability of Resin-Dentin Bonding

Objective: In an attempt to increase resindentin bonding quality, this study used baicalein as a preconditioner in an etch-and-rinse adhesive to evaluate its effect on matrix metalloproteinases (MMPs) and adhesive durability. Methods: As a MMP inhibitor and potential collagen cross-linking agent, baicalein was used as a preconditioner in an etch-and-rinse adhesive system. The degree of conversion was evaluated by Fourier-transform infrared spectroscopy. EnzChek gelatinase/collagenase assay kits were then used to detect the MMP inhibitory effect of different concentrations of baicalein (0.1, 0.5, 2.5, and 5.0 mu g/mL) on dentin powders. During in vitro bonding procedures, flat dentin surfaces on sound third molars were preconditioned with 2.5 mu g/mL baicalein after being acid-etched; this step was followed by continuation of adhesive processes and build-up of resin composite. After resin-dentin stick preparation, bonding strength, failure mode, and interface nanoleakage were respectively evaluated via microtensile testing, stereomicroscopy, and field emission scanning electron microscopy either immediately or after storage in artificial saliva for three or six months. Data were analyzed by two-way analysis of variance and Tukey test (alpha=0.05). Results: Baicalein at a concentration of 0-5.0 mu g/mL did not influence the conversion of adhesives. However, it inhibited the activities of dentin-bond gelatinase and collagenase, especially at a concentration of 2.5 mu g/mL, while effectively increasing microtensile bonding strength and decreasing nanoleakage in vitro, both immediately and after aging. Conclusions: Baicalein used as preconditioner in an etch-and-rinse adhesive system has an anti-MMP function and effectively improves resindentin bonding durability in vitro, which has potential value in clinical bonding procedures.