Microtensile bond strength of self-etching adhesive systems to differently prepared dentin

To evaluate the microtensile bond strength (microTBS) of three self-etching adhesive systems with different degrees of acidity (Clearfil SE Bond, One-Up Bond F, and Xeno III) to dentin prepared with three different methods.

Forty-five extracted human third molars were ground flat to expose occlusal dentin and polished with 600-grit abrasive paper. All teeth were randomly divided into three groups according to the preparation method: baseline surface (AP#600), steel fissure bur (SB) and regular grit diamond bur (DB). Dentin surfaces were bonded with one of the three adhesive systems; then resin composite was incrementally built up. After storage in 37 degrees C water for 24 hours, specimens were cut and trimmed to create an hourglass shape with cross sectional area of approximate 1 mm2. All specimens were subjected to microtensile bond strength testing. The bond strength data were analyzed with one and two-way ANOVA and Dunnett Multiple comparisons test at P< 0.05.

For Xeno III and One-Up Bond F, the microTBS to dentin prepared with the different methods were not significantly different. However, the microTBS of Clearfil SE Bond to dentin prepared with the diamond bur was significantly lower than the other preparation methods. Xeno III produced the lowest microTBS that were statistically different from the other adhesive systems when each preparation method was compared (P< 0.01). SEM observation of the prepared dentin surfaces showed that the diamond bur group produced a thicker smear layer that followed by steel bur and 600-grit paper. Therefore, the smear layer from diamond burs had a greater influence in decreasing microTBS of Clearfil SE Bond that has the weakest acidity self-etching adhesive systems evaluated.