In-office bleaching sensitivity with a different application

INTERVENTION: Procedure/surgery The study will be a randomized clinical trial, split‐mouth, double‐blind. Thirty‐five patients will participate in this study, where randomly, each hemiarco of the patient will receive the gingival barrier differently. In one group, the gingival barrier will only be made in the gingival sulcus, and in another group the barrier will be estenned by about 3mm until it cover the cervical area , measured with a millimeter probe. The gel used, 35% Whiteness HP hydrogen peroxide (FGM) , will be applied throughout the patient's arch for 15 uninterrupted minutes, being reapplied for another 15 minutes, resulting in 30 minutes of each whitening session, being performed 2 in all, with interval of 1 week. After this period the whitening gel will be drawn with surgical aspirator, the teeth are cleaned with gauze and rinsed, and following will be removed from the gingival barrier and retractor. Tooth Bleaching CONDITION: Dentin Sensitivity Dentin sensitivity ; Dentin Sensitivity PRIMARY OUTCOME: Expected outcome: Number of patients that report spontaneous pain in any moment of the bleaching protocol and up to 48 h post‐bleaching, through self‐report. This number will be presented as percentage of patients with tooth sensitivity and will be named absolute risk of tooth sensitivity. SECONDARY OUTCOME: Expected outcome: The difference in color between the baseline condition and post‐bleaching (1 week and 1 month) will be assessed by Vita Classical and Bleachedguide Vita shade guide as well as with the Vita Easyshade spectrophotometer. The data will be presented as means and standard deviations. Expected outcome: The intensity of tooth sensitivity will be assessed using the visual analogue scale (VAS 0‐10) and will be presented as means and standard deviations in different periods (during dental bleaching, up to 1 h, 1 h to 24 h and 24 h to 48 h post‐bleaching). INCLUSION CRITERIA: Patients will be included in this clinical trial were men and women; who were in good general and oral health; were required to have six maxillary and mandibular anterior teeth without caries lesions or restorations; the right superior incisor should be shade A2 or darker as judged by comparison with a VITA Classical value‐oriented shade guide (Vita Zahnfabrik, Bad Säckingen, Germany).