Effect of Phosphoric Acid Containing MMP-Inactivator on the Properties of Resin Bonding to Eroded Dentin.

Abstract

To evaluate the effect of two phosphoric acids containing protease inactivators (chlorhexidine and proanthocyanidin) on the resin/eroded-dentin microtensile bond strength (μTBS), nanoleakage (NL), and in situ degree of conversion (DC) of three universal adhesives applied in the etch-and-rinse mode. One hundred twenty-six molars were randomly assigned to 18 experimental conditions according to the combination of the independent variables: eroded dentin (soft drink and citric acid), adhesive (Prime&Bond Elect [PBE, Dentsply Sirona], Scotchbond Universal Adhesive [SBU, 3M Oral Care], and Tetric N-Bond Universal [TEU, Ivoclar Vivadent]), and acid pretreatment (conventional phosphoric acid [CP acid]; chlorhexidine acid [CHX acid]; and proanthocyanidin acid [PA acid]). After restorations, specimens were sectioned into resin-dentin sticks (ca 0.8 mm2) that were then tested under tension (crosshead speed: 0.5 mm/min). Selected sticks from each tooth were used to evaluate NL and DC. Data from all tests were subjected to three-way ANOVA and Tukey's test (α=0.05). Dentin eroded with citric acid showed a significant reduction in μTBS for each adhesive in comparison to dentin eroded with the soft drink (p < 0.001). For dentin eroded with CHX acid and PA acid, the μTBS (p > 0.03) significantly improved and NL decreased for all adhesives (p < 0.004); in addition, the DC improved for two of the three adhesives tested (SBU and TEU) (p < 0.03) when CHX acid and PA acid were compared to CP acid. The addition of chlorhexidine and proanthocyanidin to phosphoric acid improved the adhesive performance when compared with conventional phosphoric acid, without jeopardizing adhesive polymerization at the resin/eroded-dentin interface.