Photobiomodulation Before or After In-office Tooth Whitening for Sensitivity Reduction: a Blinded, Randomized, Controlled Study

Ethical Considerations This research project will adhere to the recommendations of CONSORT (Consolidated Standards of Reporting Trials) (Turner et al., 2012). Participants will be fully informed about the risks, methods, and objectives of this study, and their participation will require the signing of a free and informed consent form (ICF), in accordance with the Declaration of Helsinki (World Medical Association, 2013).

All collected data will be used exclusively for scientific purposes, and the identity of the participants will remain confidential. Participation in the study may be withdrawn at any time, and confidentiality will be assured even in the event of treatment discontinuation.

Sample Size Calculation The sample size for this study was determined using GPower 3.1 (Heinrich-Heine-Universität Düsseldorf, Germany). The calculation was based on a prior study by Moosavi et al. (2016), which employed a methodology similar to that proposed in this investigation. The sample size was calculated with a statistical power of 80%, an alpha error of 5%, and a predicted dropout rate of 20%. The resulting sample size for this study is 22 patients per group.

Study Design The clinical study will be a randomized, parallel, double-blind, placebo-controlled trial. Randomization will be performed to allocate participants into three different groups: PBM-Before, PBM-After, and Placebo.

All groups will undergo in-office whitening treatment with 35% hydrogen peroxide (Whiteness HP, FGM, Joinville, SC, Brazil). Three whitening sessions will be performed, with a seven-day interval between sessions.