Influence of low-level-laser therapy on the stability of orthodontic mini-screw implants. A systematic review and meta-analysis

Background The influence of low-level-laser therapy (LLLT) on the stability of orthodontic mini-screw implants (MSIs) has not been systematically reviewed. Objectives The aim was to assess the influence of LLLT on the stability of orthodontic MSIs. Methods An unrestricted search of indexed databases was performed. Selection criteria Randomized controlled clinical trials (RCTs) investigating the influence of LLLT on orthodontic MSI stability. Data collection and analysis Two authors independently performed study retrieval and selection, and data extraction. The risk of bias (RoB) of individual studies was assessed using the Cochrane RoB Tool for RCTs. Meta-analyses were performed separately for RCTs using periotest and resonance frequency analysis (RFA) to measure MSI stability; and a random effects model was applied. Subgroup analyses were performed based on the time-points of MSI stability evaluation. The quality of available evidence was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation approach. Results Initially, 1332 articles were screened. Six RCTs with a split-mouth design were included. The periotest was used in 4 RCTs and 2 RCTs used RFA to measure MSI stability. All RCTs had a low RoB. Subgroup analyses based on periotest indicated that MSIs treated with LLLT had significantly higher stability than untreated MSIs at 21 and 30 days [weighted mean difference (MD) = -2.76, confidence interval (CI): [-4.17, -1.36], P-value = 0.0001) and at 60 days (weighted MD = -3.47, CI: [-4.58, -2.36], P < 0.00001); and the level of certainty was high. Subgroup analyses based on RFA showed higher stability of MSIs treated with than without LLLT at 56 and 60 days (standardized MD = 0.82, CI: [0.32, 1.32], P = 0.001), and at 70 and 90 days (standardized MD = 0.86, CI: [0.36, 1.36], P = 0.0007); and the level of certainty was moderate. Limitations Due to limited number of relevant studies, it was not possible to perform sensitivity analysis, subgroup analyses for patient and intervention-related characteristics, and reporting biases assessment. Conclusions The role of LLLT on the secondary stability of MSIs placed in patients undergoing OT remains debatable.