The purpose of this study was to evaluate the effects of different smear layer preparations on the dentin bond strength of a universal adhesive under dynamic pulpal pressure.

Twenty-eight extracted lower third molars were used in this study. The occlusal enamel was cut to exposed dentin. The smear layers were created by #600-SiC paper, coarse diamond bur, superfine diamond bur, and carbide bur. Clearfil Tri-S Bond Universal (CBU) was used in this study. The microtensile bond strength test was performed on the different smear layer preparations and adhesives (n=7) under 15 cmH₂O of pulpal pressure. Data were analyzed using one-way ANOVA and Duncan multiple comparison test at a 95% significance level with SPSS software.

According to the statistical analysis, surface preparation influenced the bond strength (p<.01). The surface prepared by superfine diamond bur demonstrated the highest bond strength. No difference in microtensile bond strength was observed among surfaces prepared by SiC paper, coarse diamond bur, and carbide bur. From this study, it could be concluded that superfine diamond bur is recommended for tooth preparation when using universal adhesive.