Analysis of dentin bond strength and bonding interface using alternative conditioners

Abstract

This study evaluated the effects of alternative dentin conditioners on the bond strength, failure mode, and morphology of the bonding interface. Forty teeth were used for the bond strength test (n=8). The Adper Single Bond 2 (3M Oral Care) adhesive was applied on moist (control), and air-dried (experimental) etched dentin after treatment with 37% phosphoric acid (PA), 3% aluminum nitrate + 2% oxalic acid (NA), 6.8% ferric oxalate + 10% citric acid (FO), or 10% citric acid (CA). Data normality was analyzed by one-way ANOVA, followed by Tukey’s test (?=0.05). Failure modes were observed by scanning electron microscopy (SEM). The morphology of the bonding interface (n=2) was analyzed by confocal laser scanning microscopy (CLSM). Wet-bonding with PA led to higher bond strength than the other groups. Bond strengths of NA, FO, and CA did not differ among themselves (p > 0.05). Mixed failures were predominant in the control and CA groups, and adhesive failures were predominant for NA and FO. In the control group, a hybrid layer with long resin tags could be obtained. For NA and CA, the formation of poor-quality hybrid layers was evident, while no hybridization occurred in the FO group. Adhesive application on air-dried dentin etched with the tested conditioners led to poor hybrid layer formation and lower bond strengths compared to the wet-bonding with PA.