RESUMO
The purpose of this article was to assess in vitro the effects of a catalase-based neutralizer gel in the release of residual oxygen in permanent human teeth specimens exposed to 10% carbamide peroxide. Thirty teeth specimens (5.0 x 5.0 x 3.0 mm3) were randomly divided into three groups (n = 10): Group 1, nonbleached negative control specimens; Group 2, bleached positive control specimens; and Group 3, bleached specimens exposed to a catalase-based gel. The bleaching treatment was performed six hours per day for 14 days. At the end of the bleaching treatment, Group 3 specimens were immersed in a receptacle containing the catalase-based experimental gel for three minutes. Titrations were performed to determine the quantity of residual oxygen that each test specimen released, starting immediately after the end of the bleaching treatment and exposure (or not) to the catalase-based gel, and repeated on days 1-5, 10, and 15. The values obtained were statistically analyzed by ANOVA and a Tukey post hoc test (P < 0.05). The release values of residual O2 for Group 2 were equal to those of Group 1 after 10 days and to those of Group 3 after five days. The use of a catalase-based experimental neutralizer gel, applied for three minutes, reduced by half the time required for complete release of residual oxygen from tooth structure after exposure to a 10% carbamide peroxide bleaching agent.
