The aesthetics of dental elements generates great psychological and social impacts, both in the deciduous and permanent dentition. One of the techniques widely used to visually improve the appearance of teeth is bleaching. Bleaching can be performed both at home and in a dental office. In office whitening, the technique used consists of applying the whitening gel to the dental surfaces in concentrations ranging from 25% to 50% of hydrogen peroxide. However, recent studies show that low and medium concentration bleaching agents based on hydrogen peroxide have been effective and present a lower risk of sensitivity to the patient. In view of the above, this study aims to carry out a controlled and randomized clinical trial to compare the effectiveness of dental bleaching in deciduous teeth with hydrogen peroxide at concentrations of 35% and 6%. For this, 38 patients aged 03 to 06 years will be selected, allocated in 2 groups (G1 - Hydrogen Peroxide 35%, n=19 and G2- Hydrogen Peroxide 6%, n=19). Bleaching will be carried out in up to three sessions, with an interval of 7 days between them and the evaluation of color and tooth sensitivity will be carried out 48 hours after each bleaching session. The color assessment will be measured using a digital spectrometer and tooth sensitivity using the Pain Level Scale (Wong-Baker Faces®). Descriptive statistical analysis will be carried out, containing the mean and standard deviation in the calculation and normality and homogeneity tests will be carried out, for subsequent adequate statistical analysis. As a result, it is expected that there is no significant difference between the groups in terms of color variation and that the low-concentration bleaching group has the lowest sensitivity index.

Inclusion Criteria:

• Age range from 03 to 06 years old;
• Vital or non-vital teeth (already endodontically treated) with severe to moderate discoloration;
• No active carious lesions;
• No lesions in the oral cavity;
• No report of previous tooth sensitivity.

Exclusion Criteria:

- Patients who during anamnesis report allergies to dyes or latex, who withdraw from participating in the study, as well as those who do not attend the callbacks, will be excluded.