Abstract
The purpose of this study was to examine the influence of light intensity on surface free energy characteristicsand dentin bond strength of a dual-cure direct core build-up resin system.Bovine mandibular incisors were wet-ground on 600-grit SiC paper. Adhesives were applied and cured with lightintensity of 0 (no irradiation), 200, 400, or 600 mW/cm2. The surface free energy of the adhesive was determinedby measuring the contact angles of three test liquids placed on the cured adhesive. To determine the dentin bondstrength, the core build-up resin pastes were condensed into the mold on the adhesive-treated dentin surfacesaccording to the manufacturer’s instructions. The resin paste was cured with the same light intensity as thoseused for the adhesive. Specimens were stored in water maintained at 37°C for 24 h, followed by shear testing at acrosshead speed of 1.0 mm/min in a universal testing machine. One-way ANOVA and Tukey HSD test wereperformed with the significance level set at 0.05.The surface free energy of the cured adhesive decreased with an increase in the light intensity of the curing unit.The greatest bond strengths were achieved when the resin pastes were cured with the strongest light intensity.The data suggest that the dentin bond strength of the core build-up system is affected by the light intensity,which is also influenced by the surface free energy of the adhesives.