The purposes of this study were to evaluate the effect of adhesive property on microtensile bond strength and to determine the failure mode.

Flat occlusal dentin surfaces were prepared using low-speed diamond saw. The dentin was etched with 37% phosphoric acid. The following adhesives were applied to the etched dentin to manufacturer's directions; Scotchbond Multi-Purpose in group SM, Prime&Bond NT in group NT, Scotchbond Multi-Purpose followed by Tetric-flow in group TR. After adhesive application, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the 1 × 1mm² "sticks". Microtensile bond strength were determined. Each specimen was observed under stereomicroscope and scanning electron microscope (SEM) to examine the failure mode. Data were analyzed using one way ANOVA.

The results of this study were as follows;

1. The microtensile bond strength value were; group SM (18.98 ± 3.01MPa), group NT (16.01 ± 4.82MPa) and group TR (17.56 ± 3.22MPa). No significant statistical differences were observed among the groups (P>0.05).

2. Most of specimens showed mixed failure. In group TR, there was a higher number of specimens showing areas of cohesive failure in resin.