This is a randomized, controlled, double-blind and repeated-measures clinical trial evaluated the photoactivation of hydrogen peroxide gels in different concentrations with blue or violet LED in terms of whitening efficacy and tooth sensitivity.

Inclusion Criteria:

• at age 18 or older, with good general and oral health;
• possessing all six natural and healthy upper anterior teeth with a color shade of A2 or darker, determined by comparison with the Vita Classic scale;

Exclusion Criteria:

• pregnant and breastfeeding women;
• individuals with internal tooth discoloration (tetracycline stains, fluorosis or hypoplasias);
• smokers, or those with veneers or restorations on the teeth in questions were excluded;
• gingival recession;
• dentin exposure;
• periodontal disease.