Effects of low-level laser irradiation on the rate of orthodontic tooth movement and associated pain with self-ligating brackets.

Abstract

The aim of this study was to evaluate the effect of low-level laser irradiation applied at 3-week intervals on orthodontic tooth movement and pain associated with orthodontic tooth movement using self-ligating brackets. Twenty-two patients (11 male, 11 female; mean age, 19.8±3.1years) with Angle Class II Division 1 malocclusion were recruited for this split-mouth clinical trial; they required extraction of maxillary first premolars bilaterally. After leveling and alignment with self-ligating brackets (SmartClip SL3; 3M Unitek, St Paul, Minn), a 150-g force was applied to retract the canines bilaterally using 6-mm nickel-titanium closed-coil springs on 0.019 x 0.025-in stainless steel archwires. A gallium-aluminum-arsenic diode laser (iLas; Biolase, Irvine, Calif) with a wavelength of 940nm in a continuous mode (energy density, 7.5J/cm2/point; diameter of optical fiber tip, 0.04cm2) was applied at 5 points buccally and palatally around the canine roots on the experimental side; the other side was designated as the placebo. Laser irradiation was applied at baseline and then repeated after 3weeks for 2 more consecutive follow-up visits. Questionnaires based on the numeric rating scale were given to the patients to record their pain intensity for 1week. Impressions were made at each visit before the application of irradiation at baseline and the 3 visits. Models were scanned with a CAD/CAM scanner (Planmeca, Helsinki, Finland). Canine retraction was significantly greater (1.60±0.38mm) on the experimental side compared with the placebo side (0.79±0.35mm)(P<0.05). Pain was significantlyless on the experimental side only on the first day after application of LLLI and at the second visit (1.4±0.82 and 1.4±0.64) compared with the placebo sides (2.2±0.41 and 2.4±1.53). Low-level laser irradiation applied at 3-week intervals can accelerate orthodontic tooth movement and reduce the pain associated with it.