Microtensile bond strength of three simplified adhesive systems to caries-affected dentin

Abstract

The purpose of the study was to determine the microtensile bond strength of three different simplified adhesive systems to caries-affected dentin. Fifteen extracted human molars with primary carious lesions were ground flat until dentin was exposed. Soft caries-infected dentin was excavated with the help of caries detector dye. On the remaining hard dentin, a standardized smear layer was created by polishing with 600-grit SiC paper. Teeth were divided into three groups and treated with one of the three tested adhesives: Adper Scotchbond 1 XT (3M ESPE), a 2-step etch-andrinse adhesive, Clearfil S3 Bond (Kuraray), a 1-step self-etching or all-in-one adhesive, and Clearfil SE Bond (Kuraray), a 2-step self-etching adhesive. Five-mm-thick composite buildups (Z-250, 3M ESPE) were built and light cured. After water storage for 24 h at 37ºC, the bonded specimens were sectioned into bars (1.0 x 1.0 mm; n = 20 to 30). Microtensile bond strength of normal dentin specimens and caries-affected dentin specimens was measured in a universal testing machine (crosshead speed = 1 mm/min). Data were analyzed using two-way ANOVA and Tukey's post-hoc test (p < 0.05). No significant differences in bond strength values to normal dentin between the three adhesives were found. Adper Scotchbond 1 XT and Clearfil S3 Bond showed significantly lower bond strength values to caries-affected dentin. For Clearfil SE Bond, bond strength values to normal and caries-affected dentin were not significantly different. All the tested simplified adhesives showed similar bond strength values to normal dentin. For the tested 2-step etch-and-rinse adhesive and the all-in-one adhesive, the bond strength values to caries-affected dentin were lower than to normal dentin.