A systematic review of the effective laser wavelength range in delivering photobiomodulation for pain relief in active orthodontic treatment

Objective: This systematic review aimed to establish an effective wavelength range for PhotoBioModulation (PBM) to relieve pain in orthodontic treatments. Material and methods: The electronic literature search was carried out in the following databases: PubMed, ISI Web of Science, Scopus, and Cochrane. In the initial search, 255 papers were obtained. Deleting duplicates in the search left 180 items. One manually searched study was included for a total of 181 studies. According to PRISMA guidelines and a thorough analysis of their methodology, the final sample was composed of 13 RCTs. The final statistical analysis was performed in 11 studies. The statistical analysis sought to strengthen the collected data, determining the correlation coefficient (r) for the same time interval (24 h) using a scale equivalent to the standard value (0–10 cm). Aiming to reduce the effect of heterogeneity, the difference in cm between control group (GC) and experimental group (EG) averages was considered the outcome. This difference was correlated with the wavelength in nm, calculating the Pearson linear correlation coefficient, and calculating a logarithmic correlation. Results: The dispersion of the data obtained in the experimental groups at each given wavelength showed that the most significant number of studies were in the ranges of 780–830 nm. The correlation between the wavelength and the difference between the control and experimental group averages, either linear (R2 = 0.0564, r = 0.237) or logarithmic (R2 = 0.0688, r = 0.262) was not significant (P > 0.90). Therefore, pain reduction after 24 h is not significantly dependent of wavelength. Conclusion: The majority of RCTs related to pain relief in orthodontic treatment showed 780–830 nm as the most effective photobiomodulation wavelength range for orthodontic pain relief. However, pain reduction after 24 h is not significantly dependent of wavelength. The protocol was registered in PROSPERO (CRD42019119799). © 2020 Elsevier Masson SAS