Tooth whitening is one of the most indicated aesthetic procedures in dentistry and there is evidence that it interferes with aspects of patients' quality of life. However, the sensitivity, associated with the post-procedure period, challenges clinicians and researchers. The use of topic desensitizing agents could be a alternative for the control of this adverse effects of bleaching agents. The objective of this randomized clinical study, therefore, is to evaluate the effect of glutaraldehyde-based desensitizing agent associated on tooth sensitivity and tooth color after bleaching with 35% hydrogen peroxide. 25 patients will be selected divided into two groups for a double-blind and split-mouth study. Among the results it is expected: that the use of glutaraldehyde desensitizing agent helps in the control of post-bleaching sensitivity, without harming the final color obtained of patients submitted to the proposed clinical protocol.

Tooth whitening will be performed in 3 sessions with an interval of 7 days. Desensitizing agent and placebo will be applied in all sessions in a split mouth design . All groups will receive in-office bleaching treatment according to the steps described below:1 Prophylaxis; 2- Application of gingival barrier; 3- Application of the desensitizing product or placebo in accordance with the established groups; 4- Handling the bleaching material following the manufacturer's instructions: applications of whiteness HP35% bleaching gel for 15 minutes each, totaling 45 minutes; 5- Final removal of the whitening gel and the gingival barrier followed by washing with water.

Application of the desensitizer or its placebo (step 3) will follow the following sequence:1. Relative insulation with cotton rolls; 2- Active application of the product on the buccal surfaces of all teeth with the aid of a Microbrush for 10 seconds.; 3- Wait 60 seconds and apply a light jet of air until the tooth surface is no longer shiny; 4- Wash with water for 10 seconds.

To assess the patient's perception of pain, participants will be provided with a questionnaire to be filled out daily for 21 days from the first whitening treatment session. The criteria are based on the personal perception of the pain threshold, related to the level of sensitivity caused by bleaching treatment. The visual analogue scale (VAS) will be adopted as a reference. Numerical scale on which the number 0 (zero) corresponds to total absence of pain and 10 (ten) to maximum bearable pain.

The color records of the bleached teeth will be performed by a single evaluator who will do it session :T0- baseline, T1- a week after the first session; T2- a week after the second session; T3- a week after the third session. An area of interest for color registration will be the middle third of the buccal surface of the teeth, following the the guidelines of the American Dental Association. Visual analysis will be performed using a Vita Classical scale following a color scale order organized by value. A second color analysis will be performed with the aid of a spectrophotometer that acts according to the CIELab and CIEDE 2000 system. The region for color evaluation with the Easyshade will be standardized as the middle third of the buccal surface of the anterior teeth.

Inclusion Criteria:

• healthy incisors, canines and premolars;
• Do not having a diagnosis of dental hypersensitivity.
• Do not have been at desensitizing treatment in the past two years.
• Do not have been done dental whitening treatment.

Exclusion Criteria:

• Patients undergoing orthodontic treatment;

  • Presence of periodontal disease;
  • Presence of cracks or fractures in the teeth
  • Presence of restorations and prostheses in anterior teeth;
  • Presence of extensive restorations and/or deep in molars;
  • Patients with serious dental darkening internal or external ;
  • Presence of exposed dentin.
  • Pregnant and lactating women.
  • Patients on active treatment whom are using anti-inflammatory drugs and painkillers.

For the double-blind study, the evaluator and the patient will be blinded. The bleaching procedure and the therapies under study will be performed by one operator and will only involve one evaluator not participant in the randomization and without knowledge of the interventions applied in the groups. The evaluator will be responsible for measuring and tabulating information regarding sensitivity, color analysis and the impact on patients' quality of life.

The desensitizer and its placebo will be placed in similar containers so that they cannot be identified by the volunteers.