INFLUENCE OF LIGHT-INTENSITY ON SHEAR BOND STRENGTH TO DENTIN

Purpose: To investigate the influence of light intensity on dentin bond strength of five dentin bonding systems. Materials and Methods: The light intensity used to polymerize specimens was controlled at the levels of 100, 200, 400, 600, 800, and 1000 W/m(2) (470 +/- 40 nm). Labial surfaces of freshly extracted lower bovine incisors were ground with #600 grit SiC paper to expose dentin. After primer application, bonding agents were applied and bonded with resin composites. A shear bond strength test was performed and the data were analyzed by a one-way ANOVA followed by Newman-Keuls multiple comparison (P<0.05). Results: Statistical analysis of the data indicated that light intensity affected the bond strength to dentin. The mean bond strength of all bonding systems decreased with lower light intensity. The tendency of decreasing bond strength was different among the test materials and each test material had a threshold light intensity that resulted in statistically the same bond strength obtained using a light intensity of 1000 W/m(2).