Clinical research: low-level laser therapy in accelerating orthodontic tooth movement

Abstract

Background: The present study aimed to investigate the effects of low-level laser therapy (LLLT) on orthodontic tooth movement and its correlation with the levels of interleukin-1β (IL-1β), receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) in gingival crevicular fluid (GCF).

Methods: This split-mouth design study included 12 patients scheduled for the extraction of both upper first premolars. Patients were randomly selected for experimental group that received left- or right-side radiation with a diode laser (810 nm wavelength, 100 mW power output, 6.29 J/cm² energy density). Laser treatment was applied on days 0, 7, 14, and 21, after loading the canine retraction forces. GCF concentrations of IL-1β, RANKL, and OPG were analyzed. The upper arch of each patient was scanned with an intraoral scanner to assess tooth movement.

Results: The cumulative tooth movement over 28 days was significantly higher in the laser group than in the control group. We observed significant reductions in OPG levels and increases in IL-1β and RANKL levels in GCF samples on the experimental sides.

Conclusion: With the parameter settings used in this study, LLLT could, to some extent, lead to changes in bone metabolism, which could accelerate orthodontic tooth movement.

Trial registration: Chinese Clinical Trial Registry, ChiCTR2000039594. Registered 2 November 2020-Retrospectively registered, www.chictr.org.cn/edit.aspx?pid=62465&htm=4 .

Keywords: IL-1β; Low-level laser; OPG; Orthodontic tooth movement; RANKL.

Fig. 1

The left-hand coordinate system applied to image reconstructions of the mouth for measuring retraction distances. O, incisive papilla; A, median end of the right third palatal rugae; B, median end of the left third palatal rugae; P, midpoint of the orthodontic bracket on the occlusal edge. The XY plane was established based on points O, A, and B. Point O was regarded as the coordinate origin, and the X-axis points away from the origin in the O-A direction. The Y-axis is perpendicular to the X-axis through the origin, and the right side of the upper dental arch was in positive direction

Fig. 2

Comparison of movement and velocity with and without laser treatment. a The cumulative retraction of canines and b the velocity of tooth movement are shown in the control and laser groups throughout the study period. *P < 0.05 was considered significant, based on the Paired t test

Fig. 3

Changes in cytokine levels in the gingival crevicular fluid (GCF) throughout the study period. GCF concentrations of a IL-1β, b OPG, and c RANKL, and d the RANKL/OPG ratio are shown for control and laser groups. *P < 0.05 was considered significant, based on the Paired t test (for intergroup comparisons) or one-way ANOVA (for comparisons to baseline)