The Preventive and Rehabilitative Effects of Photobiomodulation on Orthodontically Induced Root Resorption: A Systematic Review of Animal Studies.

Objective: To critically assess the preventive and rehabilitative effects of photobiomodulation (PBM) on orthodontically induced root resorption (OIRR). Methods: Six databases (PubMed, Embase, Cochrane, Web of Science, Scopus and OpenGrey) were electronically searched up to September 12, 2024 to retrieve animal studies about PBM and OIRR. The risk of bias (ROB) of included studies was assessed by the SYRCLE's tool. The effects of PBM on OIRR are regarded as OIRR prevention and OIRR rehabilitation by irradiation during or after orthodontic tooth movement. The PBM protocols for reducing and rehabilitating OIRR were summarized separately. Results: A total of 15 studies were ultimately included in this review. Regarding OIRR rehabilitation, all 4 relevant studies confirmed that laser significantly reduced root resorption degree, root resorption area (RRA) and root resorption volume, respectively. As for 13 studies investigating OIRR prevention, 9 studies (5 involving laser and 4 involving light-emitting diode [LED]) supported the positive effects of PBM, 3 studies (2 involving laser and 1 involving LED) showed no effects, 1 study reported that laser irradiation increased RRA and LED did no effect. 10 studies ranked unclear ROB and 5 studies presented high ROB. Due to considerable clinical and statistical heterogeneity among included studies, the meta-analysis was not performed. Conclusion: Within current evidence of animal studies, laser-based PBM might be promising to rehabilitate OIRR. Considerable controversy still exists on the preventive effect of PBM on OIRR. Further study is needed to detect effective dose and irradiation methods of PBM on OIRR prevention.