Photobiomodulation for accelerating orthodontic tooth movement with fixed appliances: a systematic review of clinical trials

Introduction: Fixed-appliance orthodontic treatment lasts around 20 months, and prolonged treatment increases the risk of root resorption and enamel demineralization. Photobiomodulation with low-level laser or light-emitting diode light has been proposed to accelerate tooth movement, but reviews reach discordant conclusions. Methods: Systematic review reported according to PRISMA 2020. PubMed, OpenAlex, Crossref and Scopus were searched for randomized and controlled clinical trials (2015-2023) comparing low-level laser or light-emitting diode photobiomodulation with no or sham irradiation for the rate of tooth movement in patients with fixed appliances. Risk of bias was assessed with the Cochrane RoB 2 tool. A meta-analysis was not performed because of clinical heterogeneity. Results: Ten trials with 264 participants were included. Seven reported a statistically significant acceleration of tooth movement with photobiomodulation, two reported no significant difference and one reported a shorter time to space closure with similar total movement. Reported effects ranged from a cumulative canine retraction of 4.45 mm versus 3.16 mm over 12 weeks to an alignment rate of 1.27 mm per week versus 0.44 mm per week. Effects concentrated in the red and near-infrared range (650-980 nm), whereas the single blue-light trial found no effect. One trial was at low risk of bias, seven had some concerns and two were at high risk. Conclusions: Near-infrared low-level laser photobiomodulation appears to accelerate short-term orthodontic tooth movement, but the certainty of this evidence is limited by risk of bias, small samples and heterogeneous protocols. Standardized, prospectively registered trials are needed before routine clinical use.