Effect of photochemical activation of hydrogen peroxide bleaching gel\nwith and without TiO2 and different wavelengths

Abstract

Aim: To evaluate the effect of photochemical activation of hydrogen\nperoxide (H2O2) bleaching gel with different wavelengths. Methods: In\nthe study, 80 bovine incisors were used, which were stained in 25%\nsoluble coffee and divided in 4 groups. The initial color was measured\nwith the Easy Shade spectrophotometer by CIE Lab. An experimental 35%\nH2O2 bleaching gel was used, either with or without the presence of\ntitanium dioxide (TiO2) pigment, associated with two light sources: G1\n- Transparent Gel (TG) and no activation; G2 - Gel with TiO2 and\nactivation with blue LED (l=470nm)\\laser (Easy Bleach) appliance; G3 -\nGel with TiO2 and activation with ultraviolet (l=345nm - UV); G4 - TG\nand activation with UV. Three applications of the gels were made for 10\nmin, and in each, 3 activations of 3 min, with interval of 30 s between\nthem. The coloration was evaluated again and the variation in color\nperception (DE) was calculated. The data were submitted to one-way\nANOVA and Tukey's test at 5% significance level. Results: There were\nsignificant differences between G1 and G4. The greatest "E value was\nobserved in G4 (13.37). There was no statistically significant\ndifference (p>0.05) between the groups 2, 3 and 4. Conclusions: The\npresence of TiO2 particules in the bleaching gel did not interfere at\nthe bleaching results.