Effect of the photobiomodulation for acceleration of the orthodontic tooth movement: a systematic review and meta-analysis.

To determine whether the application of photobiomodulation (PBM), as an adjunctive treatment for patients with orthodontic fixed appliances, decreased the total treatment time compared to conventional orthodontics. Studies were collected from four electronic databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for systematic reviews. Eligibility criteria were full-text articles in English or Spanish with the design of randomized (RCT), non-randomized clinical trials (non-RCT), and retrospective cohort, without any restriction regarding the publication time, in which the effect of PBM using low-level laser irradiation (LLLI) and light-emitting diode (LED) for the acceleration of the orthodontic movement had been evaluated. Data collection and analysis: Two authors independently extracted data for the characteristics and outcomes of the studies selected for inclusion. The risk of bias (RoB 2 and Robins-I) and the quality assessments (GRADE) were performed. For the quantitative synthesis, the standardized mean difference was calculated for each individual study selected and then the data were combined using a random-effects meta-analysis. The total number of included studies was n = 22 (only RCT and non-RCT were found) with a total of 515 participants. The included studies exhibited high risk of bias and some concerns, though none of them presented a low risk of bias. The quality of the studies was very low. The meta-analysis showed that the means (mm) and 95% confidence intervals (95% CI) of acceleration of tooth movement at 1, 2, and 3 months were 0.50 (- 0.28, 1.28), 1.40 (0.27, 2.53), and 0.46 (- 0.33, 1.24), respectively. The analysis showed that there is no evidence to support the use of LLLI to accelerate the orthodontic movement. LED for the acceleration of orthodontic movement does not have sufficient evidence to generate conclusions about it.