Bond strength of adhesive luting agents to caries-affected dentin.

INTRODUCTION: The aim of this study was to evaluate the bond strength of adhesive luting agents to caries-affected dentin (CAD). METHODS: Forty human molars were sectioned to create dental slices presenting exposed occlusal dentin. Half of the samples were submitted to eight caries-induction demineralizing/mineralizing cycles. The pH-cycling model consisted of three hours in a demineralizing solution followed by 45 hours of immersion in a mineralizing solution. Dentin hardness was measured before and after the pH cycling. Resin cement cylinders were built up over the dentin surface using RelyX Unicem or RelyX ARC/Scotchbond Multipurpose Plus. The cement cylinders were submitted to shear load, and the data were analyzed using two-way analysis of variance (ANOVA) and Tukey test (p<0.05). Hardness data were also submitted to two-way ANOVA and Tukey test (p<0.05). The relationship of hardness vs bond strength was assessed via nonlinear regression analysis. RESULTS: Sound dentin (tested and used in caries induction) showed similar values of hardness and were superior to CAD. Both resin cements showed higher bond strength to sound dentin than to CAD. Independent of substrate, RelyX ARC showed the highest values of bond strength. A positive linear relationship between dentin hardness and bond strength was observed for both cements evaluated. CONCLUSIONS: The adhesive luting agents evaluated showed lower bond strength to CAD.