Velocity of orthodontic active space closure with and without photobiomodulation therapy: a single-center, cluster randomized clinical trial

Abstract

The objective of this two-arm, parallel randomized clinical trial was to assess the effectiveness of low-level light therapy (photobiomodulation) using an intraoral light-emitting diode (LED) device with respect to accelerating premolar extraction space closure during en masse retraction. This trial was conducted between January 2013 and February 2014 at the European Univeristy College Department of Orthodontics. The study included 60 orthodontic patients (age range, 11.3–47.1 years; mean age, 20.4 years) with premolar extractions. Patients (n = 60) were randomized into the photobiomodulation (PBM) group (n = 30) or the control group (n = 30). Eligibility criteria included no active caries, good oral hygiene, and an extraction orthodontic treatment plan. Extraction spaces were closed using NiTi closed springs utilizing 150 g of force. Extraction spaces were measured on study models at the beginning of en masse retraction (T1) and at space closure completion (T2). All measurements were obtained by a single investigator who was blinded to the group allocation of study models. The primary outcome was the velocity of extraction space closure (mm/month) during the period of en masse retraction. Treatment allocation was implemented using randomization with 2 major blocks of 30 patients, by asking each patient to draw a sealed envelope (n = 60) indicating allocation to the PBM or control group. The allocation ratio was 1:1. The PBM group of patients (n = 30) was treated with intraoral infrared LED light therapy for 3 min per arch per day using OrthoPulse™ (Biolux Research®, Vancouver, Canada) producing a continuous 850-nm wavelength and a power density of 33 mW/cm2 per arch per day to achieve a total energy density of approximately 6 J/cm2 at the surface of the device during the en masse retraction phase; patients were required to maintain over 80% compliance with daily device use. Compliance was monitored by the device controller’s onboard computer. Sixty patients were randomized between the two groups. Fifteen patients dropped out during the study period, but were accounted for in the primary analysis as an intention to treat (ITT) analysis through multiple imputations. Mean age for the PBM and control groups were 20.7 and 22 years, respectively. Patients treated with PBM exhibited a statistically significant higher velocity of space closure by 0.22 mm/month (95% confidence interval [CI], 0.09–0.49; p < 0.01). The mean velocity of space closure in the PBM group was 1.08 mm/month (SD 0.54) compared with the control group’s 0.86 mm/month (SD 0.42). A secondary analysis was conducted on the 45 patients that reached the primary outcome and did not deviate from the study protocol (15 dropout patients removed), providing 123 extraction spaces for the analysis—23 patients from the PBM group and 22 patients from the control group. No serious harms due to treatments were encountered during the study period. The results of this study suggest that PBM therapy accelerated the rate of orthodontic space closure during en masse retraction. This trial and its protocol were not registered on a publicly accessible registry.