2011 Volume 54 Issue 5 Pages 322-330
Experimental approaches for measuring adhesive bond strengths in dentistry have consisted primarily of tensile or shear bond-strength determinations performed within a defined area. Although the testing procedures used appear to be similar, the results have differed widely among studies. The purpose of this study was to investigate the influence of the bonded surface area and the crosshead speed on the tensile bond strengths of self-etch adhesives to bovine dentin. The dentin bonding systems employed in this study were Clearfil Mega Bond (Kuraray Medical) and Clearfil tri-S Bond (Kuraray Medical). Bovine mandibular incisors were mounted in self-curing resin and wet-ground with #600-grit silicon carbide paper to expose labial dentin. Adhesives were applied and resin composites were condensed into a mold (2.4 or 4.0 mm in internal diameter) on the dentin and light irradiated. The finished specimens were transferred to distilled water, and stored at 37℃ for 24 h. Ten specimens per group were tested in tensile mode in a universal testing machine (Type 5500R, Instron) at crosshead speeds of 0.1, 0.5, 1.0, 5.0, and 10.0 mm/min. Two-way ANOVA and Tukey's HSD test (α=0.05) were performed for each adhesive system. The results showed that dentin bond strength increased with increase in crosshead speed. On the other hand, bond strength increased with decrease in bonded area. Thus, a higher crosshead speed was associated with a higher dentin bond strength. This relationship was for specimens with smaller dentin bonded surface area.
