Evaluation of application protocol of the 4% hydrogen peroxide for at-home bleaching: A randomized clinical trial.

OBJECTIVE: Few studies evaluated low concentrations of hydrogen peroxide protocols. The aim of this paper was evaluated two application protocols using 4% hydrogen peroxide in at-home bleaching. MATERIALS AND METHODS: Eighty-six patients with upper canines' shade A2 or darker were randomly allocated under two experimental conditions: two daily applications of 1 h each or a 2-h single application. Color change was evaluated using Vita Classical, Vita Bleachedguide, and digital spectrophotometer weekly and 1 month after the bleaching procedure through one-way ANOVA. The risk and intensity of tooth sensitivity (TS) was assessed through visual and numeric rating scale and measured by Fisher's exact test, Mann-Whitney test and one-way ANOVA respectively. RESULTS: After 3 weeks, the mean difference for the ΔSGU Vita Classical (1.0; 95% CI -0.1 to 2.0), ΔEab (0.7; 95% CI -1.4 to 2.8), ΔE00 (0.1; 95% CI -1.4 to 1.6) and Wi (1.8; 95% CI -1.9 to 5.5) presented no difference (p > 0.08). The relative risk for TS was 0.91 (0.72 to 1.14) without significant difference neither in the risk (p = 0.6) nor in the TS intensity for both pain scales (p > 0.65). CONCLUSIONS: The application protocols evaluated (two daily applications of 1 h each or a 2-h single application) for at-home bleaching with 4% hydrogen peroxide did not showed differences in color change and tooth sensitivity. CLINICAL RELEVANCE: Higher amount of active hydrogen peroxide in two daily applications for at-home bleaching neither accelerate bleaching nor increase the risk or intensity of tooth sensibility.