Influência do led violeta e azul no clareamento e na microdureza do esmalte bovino

Abstract

One of the most commonly used aesthetic procedures in dental offices is tooth whitening. However, the diffusion capacity of hydrogen peroxide alters tooth morphology. To reduce this damage, association with a light source achieves efficient clarification while minimizing the microstructural effects on the teeth. The surface structure of the enamel of bovine teeth darkened by exposure to coffee was evaluated after subjecting them to a clarification protocol using light-emitting diodes (LEDs) in blue and violet colors. The study was conducted with a sample composed of 60 specimens prepared from the enamel surface of bovine incisor teeth and microhardness measurements were observed in specimens randomly distributed into 6 experimental groups (n = 10): G0 - negative control (no staining/no treatment), G1 - positive control (PH 35% - 3 sessions/3x15min); G2- pH 35% + blue LED - 3 sessions (3x15min + 3 sessions - 21 irradiation cycles/session); G3- blue LED - 3 sessions (21 irradiation cycles/session); G4 - pH 35% + violet LED - 3 sessions (3x15min + 3 sessions - 21 irradiation cycles/session); G5- violet LED - 3 sessions (21 irradiation cycles/session). Photoactivation of 1 min. irradiation/30 sec. rest after each cycle). In the study, the coffee pH and microhardness were analyzed using a Vickers microhardness tester, applying a 100g load for 10 seconds, at 3 times: before and after staining the test specimens (T0 and T1), and after 3 bleaching sessions (T2). Through statistical tests (Shapiro-Wilk, Levene, Anova and Tukey) with a significance level of 5%, presenting normal distribution (p >0.05) and homogeneity of variances (p > 0.05), it was found that coffee staining caused a significant reduction in the microhardness of bovine enamel (p < 0.001) and after clarification the differences were not statistically significant, but a greater reduction in hardness occurred in group G1 (p = 0.0007) compared to the control group after bleaching. Teeth treated with LEDs + PH showed greater hardness than those treated with PH alone and no differences were observed between the LEDs used. Thus, blue and violet LEDs associated with PH represent a bleaching protocol that offers a biologically safer change, since it minimizes the damage caused by the bleaching agent to the tooth structure.