Objective: The aim of this network meta-analysis (NMA) was to explore the optimal energy density (ED) for relief of orthodontic-related pain by photobiomodulation therapy. Background: Orthodontic treatment corrects the deformity of teeth, dental arch, jaw, and face using various orthodontic devices under the action of biomechanics. Materials and methods: A computerized literature search was conducted within the MEDLINE, EMBASE, Scopus, Cochrane Library, Web of Science, CNKI, Wanfang, VIP, and CBM databases to identify randomized controlled trials (RCTs) that used photobiomodulation therapy to relieve pain during orthodontic treatment. Particular inclusion and exclusion criteria were connected to recognize relevant articles. The information was extricated autonomously by two reviewers, and a quality assessment was carried out by utilizing the Cochrane Collaboration "risk of bias" tool. The RevMan 5.4 software and STATA 15.0 were utilized for data analysis. Also, the NMA was performed with mvmeta commands in Stata (StataCorp, TX). Results: Of the 1024 recognized articles, 21 RCTs were at long last included. Within the risk-of-bias assessments, 2 studies displayed a high risk, 17 an unclear risk, and 2 a low risk. The global and local inconsistency of the NMA in 1 and 2 days was not significant; however, the NMA in 3 days showed a significant inconsistency. Laser with lower ED (0-10 J/cm2) appeared to be the most noteworthy possibility to become the optimal intervention, and it also had the highest mean rank in the rankogram and the biggest value of surface under the cumulative ranking in all three NMA structures. Conclusions: On account of the limited evidence of included trials, laser with lower ED (0-10 J/cm2) appeared to be more valid than the remaining treatment modalities (laser with higher ED, placebo, and control) for pain reduction in 1, 2, and 3 days after orthodontic procedures were applied. In the future, more high-quality research with consistency in research design is needed for further evaluation.
Keywords: LLLT; PBMT; energy density; low-level laser therapy; orthodontic treatment; orthodontic-related pain; pain relieving; photobiomodulation therapy.