This study aims to evaluate the effects of prior use of non-steroidal anti-inflammatory Naproxen on risk and level of tooth sensitivity caused by in-office bleaching procedures.

Inclusion Criteria:

• At least 18 years old patients of both genders presenting good general/oral health;
• All maxillary anterior teeth presenting shade equal or darker than 2M2 at Vita bleachguide guide (Vita-Zahnfabrik, Germany);
• Signed the form accepting to participate of this study.

Exclusion Criteria:

• Presence of caries lesions, restorations and/or endodontic treatment at any maxillary anterior teeth.
• Undergone tooth-whitening procedures;
• Pregnant/lactating;
• Presence of periodontal diseases;
• Presence of severe tooth discoloration by tetracycline stains or fluorosis;
• Any kind of medicine, bruxism habits or any other pathology that can cause sensitivity (such as recession, dentin exposure);
• Continuous use of drugs with anti-inflammatory actions;
• Presence of tooth hypersensitivity at baseline measurement;
• Any known adverse effects caused by Naproxen;
• Non-attendance to any session of evaluation or bleaching.