Effect of Matrix Metalloproteinase Inhibitors on the Dentin Bond Strength and Durability of a Two-Step Universal Adhesive System

Abstract

Abstract Background and objective: The bond durability of resin adhesives to dentin decreases following the destruction of collagen fibers by matrix metalloproteinases (MMPs). According to previous studies, the inhibition of MMPs causes the stability of the hybrid layer. The aim of this study was to investigate the effect of chlorhexidine and benzalkonium chloride on the strength and durability of the dentine bond using a 2-step universal adhesive. Materials and methods: This in-vitro study was performed on 24 intact human molar teeth and a total of 144 samples. After cleaning, the teeth were cut perpendicular to the longitudinal axis underwater to remove the occlusal enamel, and then the cut surfaces were polished with silicon carbide sandpaper. The samples were randomly divided into 6 groups: Group 1: G2-BOND Universal Adhesive in etch&rinse mode without using matrix metalloproteinase inhibitor, Group 2: G2-BOND Universal Adhesive (etch&rinse) using chlorhexidine, Group 3: G2-BOND Universal Adhesive (etch&rinse) using benzalkonium chloride, group 4: G2-BOND Universal Adhesive (self etch) without using an inhibitor of matrix metalloproteinases, group 5: G2-BOND Universal Adhesive (self-etch) using chlorhexidine. Group 6: G2-BOND Universal Adhesive (self-etch) using benzalkonium chloride. The samples of each group were divided into two subgroups based on the aging method: subgroup 1: examination after 24 hours and subgroup 2: examination after 1 year. After using the MMP inhibitor, bonding was applied on all samples and then the entire dentin surface was repaired with Valux Plus composite. All the samples were kept in distilled water with a temperature of 37°C for 24 hours and then the samples of the first subgroup were thermocycled 500 times at a temperature between 5 and 55°C and the samples of the second subgroup were thermocycled 10,000 times. All samples were tested for bond strength. Statistical comparison of data was done by SPSS version 20 software and using Three Way ANOVA methods. Results: There was a statistically significant difference between the average bond strength of the groups based on the aging and the etching method, and the average bond strength at 24 hours and in the etch&rinse group was higher (P-value<0.001). The average bond strength in the Control group was significantly lower than the CHX and BAC groups (P-value < 0.05). There was no statistically significant difference between the average band strength in CHX and BAC groups (P-value > 0.05). The effect of aging on bond strength was the same in both etching methods and all three groups (MMP inhibitors and control) under investigation (P-value>0.05). Conclusion: The bond strength in the etch&rinse strategy is higher than self etch. The use of MMP inhibitors improves bond strength.