Micro-shear bond strength of universal adhesives to caries- affected dentin; self-etch or etch-and-rinse strategy?

Introduction: The purpose of this study was to investigate the micro-shear bond strength of caries-affected dentin, using three universal adhesives either the self-etch or etch-and-rinse strategy. Methods: A total of 180 resin composite cylinders (n=20 in each group) were bonded to caries-affected dentin tissue (A total of 90 carious human mandibular molar teeth were used, with 2 resin composite cylindrical samples on each tooth) using three universal adhesives [All Bond Universal (ABU), Futura Bond Universal (FU), (Single Bond Universal (SBU).] with, or without, acid etching and three conventional adhesives [Clearfil Tri-S Bond (TSB), Clearfil SE Bond (CSE), Single Bond 2 (SB2).]. After 5000 thermo-cycling rounds, a universal test device micro-shear bond strength test was realized at a crosshead speed of 0.5 mm/min to evaluate the bond strength of samples the debonding surfaces were assessed under the SEM. Two-way ANOVA and Tukey's Post-hoc tests were used to analyse the data. Results: While acid etching increased the bond strength of FU significantly (p=0.003), it decreased the bond strength of SBU significantly (p=0.002) and did not change the bond strength of ABU (p=1.00). Discussion and conclusion: The bond strength of universal adhesives on caries-affected dentin with, and without, acid etching depends on which universal adhesive system was used.