The effectiveness of low-level laser therapy in accelerating orthodontic tooth movement: a meta-analysis

Low-level laser therapy is claimed to accelerate bone remodeling. The aim of this meta-analysis was to critically appraise current evidence and to determine the effectiveness of low-level laser therapy in accelerating orthodontic tooth movement. PubMed, Web of Knowledge, Embase, CENTRAL, ProQuest Dissertations &Theses, and SIGLE were electronically searched from Jan 1990 to Jun 2013. Article screening, data extraction, assessment of risk of bias and evaluation of evidence quality through GRADE were conducted independently and in duplicate by two reviewer authors. Outcome of interest in this meta-analysis was accumulative moved distance (AMD). Meta-analyses were performed in Comprehensive Meta-Analysis Version 2.2.064 (Biostat, Englewood, NJ, USA). Finally, five studies were included in this meta-analysis. The meta-analysis revealed that the pooled difference in mean (DM) was 0.33 [95 % CI: (0.03–0.64)], 0.76 [95 % CI: (−0.14, 1.65)] and 0.43 [95 % CI: (−0.05, 0.91)] for AMD within 1 month, AMD within 2 months and AMD within 3 months, respectively. However, significant heterogeneities and instability of the pooled results were detected. Moreover, publication bias was found for AMD within 3 months. The subgroup analysis on the wavelength of 780 nm revealed that the pooled DM of AMD were 0.54 (95 % CI = 0.18–0.91), 1.11 (95 % CI = 0.91–1.31) and 1.25 (95 % CI = 0.68–1.82) for 1, 2, and 3 months, respectively. For the output power of 20 mW, the subgroup analysis showed that the pooled DM of AMD was 0.45 (95 % CI = 0.26–0.64), 1.11 (95 % CI = 0.91–1.31), and 1.25 (95 % CI = 0.68–1.82) for 1, 2, and 3 months, respectively. Weak evidence suggests that low-level laser irradiations at the wavelength of 780 nm, at the fluence of 5 J/cm2 and/or the output power of 20 mW could accelerate orthodontic tooth movement within 2 months and 3 months. However, we cannot determine its effectiveness within 1 month due to potential measurement errors.