For color analysis, the parameter delta data L *, a * and b *, and ΔE and Δ00, will be individually subjected to two-way repeated measures ANOVA test to compare the two bleaching techniques at each evaluation time. Based on presence of any tooth sensitivity (scores different from 0 for VRS), the absolute risk, odds ratio and relative risk will be calculated regarding the treatments for each moment of evaluation/session of bleaching, as well as its confidence intervals (95%). For each moment, differences on presence/absence ratios will be analyzed by Fisher's exact test. For the overall risk related to each treatment, the odds ratio will be adjusted to independent variable "session of bleaching" using the Mantel-Haenszel statistic. The homogeneity of odds ratios will be analyzed by the Breslow-Day and Tarone's tests. Following, the odds ratio estimated will be converted to relative risk and the overall presence/absence ratios will be analyzed by the McNemar's test, considering the study design (parallel).