Analyses by photoreflectance spectroscopy and Vickers hardness of conventional and laser-assisted tooth bleaching

Purpose: To evaluate the in vitro effects of two bleaching products developed to be used with halogen or argon laser lights. Methods: 20 human embedded third molars were cut into four parts resulting in 75 useful specimens. The specimens were divided at random into five groups and submitted to the traditional power bleaching procedure for enamel. Group C was separated as a control group. Group 37L was exposed to a 37% carbamide peroxide bleaching solution and exposed to 488 nm argon laser radiation. The same solution was used in Group 37H but the bleaching was exposed to a halogen lamp-based unit. The 35% carbamide peroxide was used in Groups 35L and 35H. One was treated as in Group 37L and the other as in Group 37H. The samples were analyzed for Vickers hardness and also by photoreflectance. Results: Group 37L presented more white spectra than Group 37H. However, Groups 35L and 35H showed similar results. Comparing both bleaching products, the 35% carbamide peroxide was more effective as a bleaching agent than the 37% formulation. No significant difference in Vickers hardness was noted between the two bleaching products.