Effectiveness of low-level laser therapy in accelerating the orthodontic tooth movement: A systematic review and meta-analysis

Abstract

Objectives: The aim of the paper was to appraise the current evidence of the effectiveness of low-level laser therapy (LLLT) in accelerating the tooth movement.

Methods: A comprehensive search was performed in 9 databases up to June 2019. Only randomized controlled trials (RCTs) were included. The risk of bias was assessed using the Cochrane Collaboration tool. The quantitative data synthesis was attainable only for the studies evaluating the effect of laser on canine retraction; the qualitative description was used for the rest of the studies. The overall quality of evidence was rated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.

Results: A total of 25 RCTs were included in this review. The radiated upper canines showed a greater retraction – 0.50 mm and 0.49 mm at months 2 and 3, respectively. The radiated lower canines showed a greater retraction – 0.28 mm and 0.52 mm at months 2 and 3, respectively. No statistically significant differences were observed among the upper and lower canines after the 1st month of retraction. When the GRADE approach was utilized, the overall quality of evidence limited confidence in the estimates. The qualitative description revealed enhanced tooth movement when LLLT was applied. The attrition bias was the main risk factor affecting the methodology of the studies.

Conclusion: Low-level laser therapy can speed up the rate of the tooth movement. However, the overall quality of evidence ranged from low to very low and the clinical significance of the obtained statistically significant differences is questionable. Hence, more precise studies are needed. As discussed in this review, it is highly recommended to express and compare the laser dosage with the total number of joules applied per month rather than the previously used J/cm2. Moreover, the previous recommendation indicating that lower energy densities (2.5, 5 and 8 J/cm2) are more effective than 20 and 25 J/cm2 is misleading.

Keywords: acceleration; lasers; low-level laser therapy; orthodontics.