Avaliação clínica da degradação de géis clareadores com diferentes pHs durante o clareamento dental em consultório

Abstract

Objective: To evaluate the degradation rate of active hydrogen peroxide (HP) during in-office bleaching using high-concentration HP gels with different baseline pHs. Method: A randomized, parallel, double-blind controlled trial was conducted with 40 volunteers randomized into four groups according to bleaching gel pH (pH 5.4; pH 7.0; pH 7.7 and pH 8.0). During the first session in-office bleaching, approximately 0.01g of the gel in contact with the enamel surface was collected at 0, 10, 20, 30, 40, and 50 min. The gel was titrated with potassium permanganate to obtain the concentration of active HP, and pH values were measured using an electrode in contact with the gel and enamel surface. Bleaching efficacy was assessed as a secondary outcome using the Vita Easyshade spectrophotometer [∆Eab, ∆E00, and WID] and Vita Classical and Vita Bleachedguide scales [∆SGU] at baseline, 7 days, 14 days, and one month after bleaching. The degradation rate of HP concentration, pH values change, bleaching efficacy [∆Eab, ∆E00, WID, and ∆SGU] were calculated using ANOVA one-way and Tukey’s test. For all statistical tests the significance level was set at 5%. Results: A significant decrease in the HP concentration over time was observed for all gels. Among the gels, pH 5.4 exhibited highest reduction in HP concentration after 50 min (p<0.001). The gels with pH 8.0 and pH 7.7 remained stable during bleaching; the gel of pH 5.4 remained acidand the gel with pH 7.0 transited to an acid pH after 50 min (p<0.001). All gels whitened teeth after the two sessions, but the gel with pH 5.4 yielded a lower degree of whitening. Conclusions: All bleaching gels retained at least 70% of their HP content after 50 min, suggesting that there is a surplus of HP that may not be bringing benefits but greater side effects.