Effect of irradiation time to light-cured resin composite on dentin bond strength

This study examined the relationship between the irradiation time of three light-cured resin composites and their bond strength to dentin using two adherend surfaces. The light-cured resin composite systems selected were: Scotchbond/Silux, Scotchbond 2/Silux, and Clearfil Photo Bond/Photo Clearfil A. The adherend surfaces selected were a flat dentin surface and a box-shaped cavity. The greatest bond strength for all resin systems was recorded using the longest irradiation time. The bond strengths increased with an elevated irradiation time. When comparing the flat surface and a box-shaped cavity, the bond strength of the box cavity was greater than the flat surface with similar conditions except for 20 and 30 seconds of Scotchbond and 30 seconds of Clearfil. The correlation between bond strength and irradiation was greater for the flat surface than for the box-shaped cavity. This implied that the bond strength of the box-shaped cavity may be more susceptible to polymerization shrinkage.