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

Background: The aim of this study was to investigate the effects of using two types of matrix metalloproteinase inhibitors (MMPI) on the dentin bond strength and durability of a two-step universal adhesive (G2-BOND Universal Adhesive).

Material and methods: This study was conducted on 24 extracted molars, resulting in 144 samples. The occlusal surface of the teeth was cut perpendicularly to the longitudinal axis to expose the dentin. The samples were divided into 6 groups: Group 1 (Control, etch-and-rinse (ER)): bonding in the ER mode without MMPI; Group 2: bonding in the ER mode with chlorhexidine (CHX); Group 3: bonding in the ER mode with benzalkonium chloride (BAC); Group 4 (Control, Self-etch (SE)): bonding in the SE mode without MMPI; Group 5: bonding in the SE mode with CHX; Group 6: bonding in the SE mode with BAC. The entire dentin surface was restored with composite resin. Each group was further divided into two subgroups and either thermocycled for 500 or 10,000 cycles. The samples were cut into cylinders with a one square millimeter cross-sectional area and tested for microtensile bond strength (µTBS). Data was analyzed using 3-Way ANOVA and Games-Howell tests (p< 0.05).

Results: There was a statistically significant difference in the mean µTBS based on the type of MMPI, aging method, and etching strategy. The mean µTBS in the Control group was significantly lower than in the CHX and BAC groups (P< 0.05). The mean µTBS was higher at 24 hours and in the ER group (P< 0.001). The effect of aging was consistent and decreasing (P> 0.05).

Conclusions: The µTBS to dentin decreases after aging. However, the use of MMPI preserves bond strength to some extent in comparison to control groups after aging. Key words:Universal adhesive, Matrix metalloproteinase, Bond strength, Chlorhexidine, Benzalkonium chloride.