The effect of the loading method and cross-head speed on resin–dentin microshear bond strength

This study compared the effect of different loading methods and cross­head speeds on resin–dentin microshear bond strength (μSBS) using two etch­and­rinse adhesive systems. Sixty molar teeth had their dentin surfaces exposed and were randomly distributed into 12 groups (n=5), according to a combination of the factors: loading methods (orthodontic-looped wire and chisel systems), cross-head speed (0.5, 1.0 and 5.0 mm/min) and adhesive system (Adper Single Bond 2 and XP Bond). Five tygon tubes were positioned over each sample, filled with composite resin and photoactivated. After 24 h, they were tested. The data were analyzed with a two-way ANOVA and Tukey test (α=0.05). The µSBS of the adhesives was higher with the chisel methods, compared to the orthodontic-looped wire (p<0.05). The cross-head speed was only significant for the chisel (p<0.05). The evaluated test variables affect the µSBS for both adhesives and therefore should be standardized; however the loading method proved to have the most effect on μSBS values.