Eligibility criteria
carious lesions, discoloration, parafunction, fluorosis, tooth
PERIODONTAL DISEASE
Inclusion criteria: Adolescents aged 12 to 16 years, with vital teeth, no periodontal disease, carious lesions, endodontic treatment, in good oral and general health, and with both upper canines colored A2 or darker, according to the VITA Classical Shade Guide (VITA Zahnfabrik, Bad Säckingen, Germany). Moreover, their guardians read and signed an informed consent form before their inclusion in the study.Exclusion criteria: Participants who had undergone previous tooth bleaching, had previous TS, were on chronic medication, used fixed orthodontic appliance or prosthesis, had gingival recession, parafunction, discoloration due to tetracycline or fluorosis, were pregnant or lactating women, smoked, or had visible cracks in their teeth.All data were collected from September 2021 to January 2022 at the State Univesity of Ponta Grossa.