Estudo de técnicas e protocolos para o clareamento de dentes vitais e tratados endodonticamente

Abstract

Dental bleaching is a process that aims to enhance esthetics and correct undesired dental discolorations, regardless of whether or not the teeth have undergone endodontic treatment. The present thesis consists of two studies, the first is a laboratory investigation, in which forty human third molars were stained with black tea and randomized (n=10) into groups according to the bleaching agent and protocol for In-office bleaching: 35% hydrogen peroxide (HP) and 37% carbamide peroxide (CP), traditional and alternative protocols. The traditional protocols consisted of 3 applications of HP for 15 minutes each and 1 application of CP for 45 minutes, and the alternative protocols, of 1 application of HP for 45 minutes and 3 applications of CP for 45 minutes each. Both protocols were, applied for 3 consecutive weeks. Color measurements were conducted at baseline (T0) and weekly (T1, T2 and T3), until completion of treatments, and again at the one-week (T4), six-month (T5) and one-year follow-ups (T6). CIEL*a*b* coordinates were measured, chroma (C*), hue angle (hº) and whiteness index (WID) were calculated. CIEDE2000 color differences and whiteness differences among consecutive evaluation time points were calculated. Effectiveness and stability of the bleaching treatments were interpreted by 50:50% perceptibility (PT) and acceptability thresholds (AT), and recommended ratings. Mean values of L*, a*, b*, C, ho and WID were analyzed by the Wilcoxon Signed Rank Test, with p<0.05 level of significance. All protocols presented ΔWID >7.8 at T1- T0, demonstrating excellent bleaching effectiveness. The alternative protocols presented a greater rebound effect after one year, indicating less color stability over time. The second study is a randomized clinical trial, in which fifty-four discolored teeth with endodontic treatment were selected according to inclusion and exclusion criteria, randomized and allocated into three groups (n=18) according to the bleaching techniques: walking bleach using sodium perborate (SP), inside/outside using 7.5% hydrogen peroxide (HP7.5), and in-office bleaching using 35% hydrogen peroxide (HP35). A cervical seal was applied to all teeth before each protocol. Initial L*, a*, and b* coordinates (T0) were assessed using a clinical spectrophotometer, on a weekly basis (T1-T2-T3), and at one week following treatment completion (T4). ΔE00 and ΔWID were determined between the baseline and each assessment time. ANOVA, Fisher's Exact, and Kruskal-Wallis tests were employed to correlate categorical variables. The effectiveness of the bleaching treatments was interpreted using the 50:50% perceptibility (PT) and acceptability (AT) thresholds for visual color differentiation. No substantial differences were noted among the tested techniques at T4 concerning ΔE00 and ΔWID, according with PT and AT. All techniques presented excellent effectiveness one week after the completion of the treatments. However, the HP7.5 and HP35 techniques yielded a swifter response to the whitening treatment. However, HP7.5 and HP35 techniques provided a more rapid whitening response.