Many efforts have been made to shorten fixed appliance orthodontic treatment time by accelerating the rate of tooth movement. Low-intensity electrical stimulation (LIES) is one of the proposed physical methods that has not yet been well studied in the medical literature. This study aimed to evaluate the effectiveness of LIES in accelerating orthodontic tooth movement in cases of en-mass retraction of the upper anterior teeth.

Patients who attended the Department of Orthodontics at the Faculty of Dentistry, University of Damascus, between September 2019 and February 2021, for treatment were carefully checked. All patients who met the eligibility criteria were invited to participate in this RCT. Young adult patients having class II division I malocclusion were equally and randomly assigned into the low-intensity electrical stimulation group (LIES), and traditional en-masse retraction group (TRAD). The mini-implants assisted en-masse retraction technique was used to close the extracted upper first premolar spaces in both groups. NiTi closed coil springs (250g/side) were used. Electrical stimulation of 15-20μA for each tooth was applied on the upper anterior teeth using a recently developed intraorally removable device in the LIES group. The primary outcome was the en-masse retraction rate, the secondary outcomes were changes in the first molar position, intermolar width, and intercanine width. These outcomes were measured on the digital photographs of the maxilla cast using the Image J program. Two-sample t-test with Bonferroni's correction was utilized to explore any significant differences between the two groups in all studied variables.

Of the 168 patients examined by the researcher, 38 patients with Class II division I malocclusion (30 females and 8 males; mean age: 21.1±2.31 years) were finally recruited in this RCT. The overall en-masse retraction rate was significantly greater in the LIES group compared to the TRAD group (1.02±0.08, 0.73±0.04mm/month respectively; P<0.001). In addition, the monthly rate of space closure was significantly greater in this group at all evaluation times (P<0.001). A small increase was noted in the intercanine width (1.60±0.27, and 1.65±0.33mm respectively). Negligible changes were noted in the first molar positions and intermolar width, with insignificant differences between the two groups.

LIES according to the protocol applied in this trial accelerated the upper anterior teeth en-masse retraction rate by approximately 28% compared to the traditional en-masse retraction method. While this acceleration was statistically significant, may not have substantial clinical implications.

This trial protocol was registered in the Clinical Trials database (ClinicalTrials.gov NCT05350280).