Inclusion Criteria:  patients between 18 and 30 years of age, with fully erupted upper and lower incisors and canines without dental or periodontal disease or restorations, and with at least one maxillary tooth presenting color score A3 or darker, as measured with the Vita Classical guide (Vita Zahnfabrik, Bad Sa # ckingen, Germany) ordered by brightness  Exclusion Criteria:  patients with systemic diseases or oral mucosal disorders, previous bleaching treatment, patients undergoing orthodontic treatment, pregnant or lactating women , people with known allergy to the product ingredients, smokers, and alcohol abusers, had severe internal tooth discoloration (e.g. tetracycline stains), had bruxism or any other pathology that could cause TS (such as gingival recession or dentin exposure).