Influência de agentes clareadores na microdureza de dentes bovinos submetidos à radioterapia

Abstract

This work’s objective was to evaluate the effect of different tooth whitening protocols and materials on the microhardness of irradiated and non-irradiated bovine enamels. Methodology: 64 bovine teeth were selected, their roots were sectioned at the cementoenamel junction and included individually in the vertical position in acrylic resin. The IR-irradiated group (n = 48) underwent the irradiation protocol with fractional doses of 2 Gy / day, adding, at the end, 50 Gy. The C-Control group (n = 48) was stored in distilled water, at 37ºC. The specimens of each group were randomized and divided into 4 subgroups, for whitening, for 21 days. 1- control group without intervention; 2- homemade whitening (Carbamide Peroxide at 16% - FGM); 3- in-office whitening (Hydrogen Peroxide at 35% - FGM); 4- home whitening associated with the in-office whitening (Carbamide Peroxide at 16% + Hydrogen Peroxide at 35%). The bleaching protocols duration was 21 days for all groups. The specimens were evaluated for Knoop microhardness (Mitutoyo-Shimatzu) from the arithmetic mean of three indentations (0.05 (490.3 mN)) performed on the dental enamel in a single time, after the irradiation and whitening protocol. Results: Exploratory analysis (Shapiro-Wilk; p> 0.05) and other variance parameters (ANOVA) were performed, in a factorial scheme (4x2). The multiple comparisons between the hardness averages (Tukey) revealed that irradiation did not reduce the microhardness of the control groups, the irradiation associated with bleaching reduced the microhardness of irradiated and non-irradiated bovine enamel, and the groups submitted to the in-office bleaching technique associated with the homemade showed a significant reduction in microhardness when compared to control groups.