Photobiomodulation in orthodontics: an overview of systematic reviews with meta-regression and evidence map.

Photobiomodulation (PBM) has been studied as a potential addition to orthodontic treatment; however, concerns have been raised about inconsistent results. This overview summarizes systematic reviews (SRs) evaluating the effectiveness of PBM in orthodontic procedures. We systematically searched eight databases (PubMed, Cochrane, Embase, Scopus, Web of Science, ProQuest, Google Scholar, VHL). Methodological quality was independently assessed by three reviewers using the AMSTAR 2 tool. Citation matrix analysis was performed to measure overlap among primary studies. Data on orthodontic tooth movement (OTM) were reanalyzed using meta-regression models (alpha = 5%). Evidence certainty was graded with GRADE. This overview included 40 SRs with 134 primary studies (n = 4730 participants). Most reviews were rated as critically low in quality. For OTM, meta-regression of only low-bias primary studies indicated that PBM accelerates tooth movement by roughly 1 mm over 3 months (Standardized Paired Difference = 0.99, 95% Confidence Interval = 0.32-1.67; p = 0.004). PBM seems to reduce pain after separator placement, although with limited clinical significance. It may also enhance miniscrew stability, but this is based on very low-certainty evidence. Other outcomes-such as periodontal health, orthodontically induced inflammatory root resorption, and rapid maxillary expansion-show no difference between PBM and control groups. In conclusion, current evidence does not support the routine clinical use of PBM in orthodontics. Future studies should focus on improving methodological quality before considering PBM as an evidence-based adjunct therapy.