The main objective of this study is to evaluate if the use of UltraEZ during at-home bleaching treatment is effective in reducing tooth sensitivity, as well as doesn't affect the degree of tooth bleaching.

1. Visit 1: Study information and delivery of informed consent. Recording of the patient's medical history, general examination, and prophylaxis. Alginate impressions will be taken of the upper and lower arches for all patients who meet the inclusion criteria. The impressions will be poured into plaster, and individualized bleaching trays will be made for each patient. A positioning guide tray will be fabricated for color measurement.
2. Visit 2: Initial color measurement with a spectrophotometer and the positioning guide. Each patient will receive their individualized trays. Additionally, they will be given 3 syringes of bleaching agent (Opalescence 16%, Ultradent Products) and one syringe of desensitizing agent (UltraEZ, Ultradent Products) or placebo (glycerin), according to their study group. Both the desensitizing agent and placebo will be dispensed in identical syringes, coded as A and B, to ensure the blinding of the study; only the clinician responsible for randomization knows the coding. Each patient will be provided with an instruction sheet and recording sheets to fill out daily during the 3-week study period. They will record the degree of dental sensitivity .
3. Visit 3: First-week bleaching review. Data collection (color + sensitivity).
4. Visit 4: Second-week bleaching review. Data collection (color + sensitivity).
5. Visit 5: Third-week bleaching review and end of the study. Data collection (color + sensitivity).

Inclusion Criteria:

• No oral or systemic pathology
• Periodontally healthy
• No cavities
• Tooth shade of the upper and lower canines A2 or darker

Exclusion Criteria:

• Adhesive restorations or prostheses in the anterior region
• Enamel or dentin alterations
• Smoking
• Pregnant women
• Undergone prior bleaching treatment