Photobiomodulation Reduces Pain-Related Symptoms Without Interfering in the Efficacy of In-Office Tooth Bleaching: A Systematic Review and Meta-Analysis of Placebo-Controlled Clinical Trials.

Objective: This systematic review aimed to determine whether the use of photobiomodulation (PBM) with low-level laser therapy prevents tooth sensitivity induced by in-office tooth bleaching with hydrogen. Methods: Placebo-controlled clinical trials were included to evaluate the efficacy of PBM with low-level laser therapy in the prevention of tooth sensitivity after in-office tooth bleaching. Searches were conducted on the Medline database via PubMed, Scopus, Web of Science, EBSCO, SciELO, LILACS, Cochrane, DOSS, and Google Scholar until July 2020, and fixed-effects meta-analysis was performed for tooth sensitivity [standardized mean differences (MDs)] and color changes (MDs). Results: Five studies were included in this systematic review and meta-analysis, with a total of 288 patients, 123 patients in the PBM group and 165 patients in the placebo group. In the meta-analysis, despite high heterogeneity, PBM significantly reduced the tooth sensitivity after the first [ p  < 0.001; Cohen's d  = -0.32, 95% confidence interval (CI) = -0.46 to -0.18], second ( p  < 0.001; Cohen's d  = -0.30, 95% CI = -0.46 to -0.15), and third ( p  < 0.001; Cohen's d  = -0.82, 95% CI = -1.06 to -0.58) sessions of in-office tooth bleaching, without impairing the Δ E ( p  = 0.300). Conclusions: The results of this systematic review and meta-analysis suggest that PBM significantly prevents pain-related symptoms after the first three weekly sessions of in-office tooth bleaching with hydrogen.