Photobiomodulation accelerates orthodontic alignment in the early phase of treatment

Abstract

Background: Numerous strategies have been proposed to decrease the treatment time a patient requires in orthodontic treatment. Recently, a number of device-accelerated therapies have emerged in orthodontics. Photobiomodulation is an emerging area of science that has clinical applications in a number of human biological processes. The aim of this study was to determine if photobiomodulation reduces the treatment time in the alignment phase of orthodontic treatment.

Methods: This multicenter clinical trial was performed on 90 subjects (73 test subjects and 17 controls), and Little's Index of Irregularity (LII) was used as a measure of the rate of change of tooth movement. Subjects requiring orthodontic treatment were recruited into the study, and the LII was measured at regular time intervals. Test subjects used a device which produced near-infrared light with a continuous 850-nm wavelength. The surface of the cheek was irradiated with a power density of 60 mW/cm2 for 20 or 30 min/day or 60 min/week to achieve total energy densities of 72, 108, or 216 J/cm2, respectively. All subjects were fitted with traditional orthodontic brackets and wires. The wire sequences for each site were standardized to an initial round alignment wire (014 NiTi or 016 NiTi) and then advanced through a progression of stiffer arch wires unit alignment occurred (LII<1 mm).

Results: The mean LII scores at the start of the clinical trial for the test and control groups were 6.35 and 5.04 mm, respectively. Multi-level mixed effect regression analysis was performed on the data, and the mean rate of change in LII was 0.49 and 1.12 mm/week for the control and test groups, respectively.

Conclusions: Photobiomodulation produced clinically significant changes in the rates of tooth movement as compared to the control group during the alignment phase of orthodontic treatment.

Figure 1

Device components and a clinical presentation. (A, B) A set of four extra-oral treatment arrays, each with a flexible printed circuit board and a set of LEDs mounted on a contoured heat sink and infrared-transmissible plastic lens, with conductive cables to the controller. (C) A headset similar to an eyeglass support structure to be worn by the patient on a daily or weekly basis, with attachment and adjustment mechanisms to position the treatment arrays in the appropriate location for the given patient. (D, E, F) Clinical presentation of the device.

Figure 2

A representative case treated with conventional orthodontic method in the control group. (A) Baseline (day 0); LII is 3.80 mm. (B) Day 42; LII is 2.20 mm. (C) Day 119; LII is 1.70 mm. (D) Day 161; LII is 0.50 mm.

Figure 3

A representative case treated with LAO method in the test group. (A) Baseline (day 0); LII is 12.16 mm. (B) Day 14; LII is 9.30 mm. (C) Day 26; LII is 1.26 mm. (D) Day 56; LII is 0.00 mm.

Figure 4

Box plots showing differences in alignment rates (mm/week) between control and test (LAO) patients. The box plots were created using arch level data to provide a more accurate weighting of alignment rates over total treatment time. Arch level summaries and Wilcoxon rank-sum tests revealed that the combined LAO arches started at a higher average LII (8.39 mm versus 6.67 mm). There was no statistically significant difference between the two groups in terms of destination LII. Outliers (rates greater than 3 mm/week) were removed from the test group to make these figures more conservative. The test group's mean alignment rates were 0.99 compared to a control rate of 0.44, with a comparison group of 23 control arches and 111 treatment arches.