Effect of photobiomodulation therapy on mini-implant stability: a systematic review and meta-analysis

The study aimed to assess trials investigating the effect of PBMT on mini-implant stability. Electronic searches of seven databases and manual search were conducted up to May 2020. Randomized controlled trials and controlled clinical trials evaluating the effect of PBMT on mini-implant stability were included. The risks of bias of individual studies were performed using ROB 2.0 and ROBINS-I-tool based on different study design. Meta-analysis was conducted to compare mini-implant stability exposed to PBMT with control ones at different time points after implantation. Among the 518 records initially identified, seven studies were included in this study. Six studies investigated low-level laser therapy (LLLT) and one study evaluated light-emitting diode (LED) therapy. Two studies were eligible for meta-analysis, which showed that LLLT significantly improved mini-implant stability 60 days after initial implantation (MD - 3.01, 95% CI range [- 4.68, - 1.35], p = 0.0004). High energy density of LLLT began to show beneficial effect on mini-implant stability as early as 3 days after implantation, while the significant effect of low energy density displayed later than 30 days after insertion. LED therapy could improve mini-implant stability after 2 months post-insertion. In conclusion, PBMT appears to be beneficial in ameliorating mini-implant stability. High energy density of LLLT might exert more rapid effect than low energy density. More high-quality clinical trials are needed to further demonstrate PBMT' effects on orthodontic mini-implants.