Effectiveness of photobiomodulation with low-level lasers on the acceleration of orthodontic tooth movement: an umbrella review.

Introduction: Photobiomodulation (PBM) with low-level laser therapy (LLLT) is a non-invasive method for accelerating orthodontic tooth movement (OTM). Several systematic reviews (SRs) have assessed the effectiveness of LLLT on OTM acceleration. However, the interpretations and analysis of the findings of these SRs are inconclusive and inconsistent due to the substantial heterogeneity of their results, mainly due to the wide variety of parameters employed in the primary studies. This umbrella review (UR) aims to (i) Evaluate and summarize the findings of SRs evaluating the effect of LLLT on OTM acceleration. (ii) Suggest an evidence-based protocol with the most predictable application LLLT parameters for OTM acceleration.

Methods: Medline (PubMed), Web of Science, and Scopus were searched from inception to December 2023. AMSTAR-2 and ROBIS were used to evaluate methodological quality and risk of bias respectively.

Results: Six SRs met the inclusion criteria. All the SRs suggest that PBM with LLLT tends to be effective in accelerating OTM. However, the high heterogeneity of SRs hinders a precise evaluation of the LLLT's effect on OTM acceleration. The parameters most associated with OTM acceleration are LLLT frequency: At least twice a month, irradiation points: 4-10 points, irradiation time per point: 3-50 s, output power: 20-150 mW, energy density: 5.3 J/cm2 and wavelength range:780-810 nm. The risk of bias assessment identified that 50% of the included SR had a risk of bias ranging from uncertain to high. Similarly, three SRs obtained a "Critically low-quality" assessment.

Conclusions: Although, all the SRs included in this UR suggest that LLLT may accelerate OTM in comparison to control groups. The primary goal of future studies examining the influence of LLLT on the acceleration of OTM should be to create standardised protocols for the use of LLLT, allowing the development of more predictable therapies. The research protocol was registered on the Prospero CRD42024497420.