Evaluation of dental enamel microproperties after bleaching with 35% hydrogen peroxide and different light sources: An in vitro study

Abstract

Background: To evaluate the tooth enamel surface morphology after the action of 35% hydrogen peroxide with and without LED activation. Material and Methods: 70 bovine incisors with an enamel surface of 4x4x3 mm were used, prepared for reading superficial microhardness and roughness. Specimens were randomly distributed and divided into 7 experimental groups (n = 10); G1 = artificial saliva; G2 = 35% HP - 2 sessions (3x15'); G3 = Phosphoric Acid + 35% HP - 3 sessions (3x15'); G4 = 35% HP - 2 sessions (3x15') + blue LED; G5 = 35% HP - 2 sessions (3x15') + green LED; G6 = 35% HP - 2 sessions (3x20') + violet LED; G7 = Violet LED - 2 sessions (3x20'). The results were analyzed by the Anova, Wilcoxon, Dunnett and Tukey tests (a = 0.05). Results: The G4 group showed a greater change in microhardness. Regarding roughness, the biggest mean difference between groups occurred in G2, G5 and G7. Optical microscopy showed a smooth enamel surface in groups G2, G5 and G7. Conclusions: changes in the enamel surface were observed in relation to microhardness, but without significant changes in roughness, where the LED (green and violet) resulted in a smooth surface.