Introduction
This split-mouth trial aimed to examine the effects of light-emitting diode (LED)–mediated photobiomodulation compared with no photobiomodulation on maxillary canine distalization.
Methods
Twenty participants (10 males and 10 females; aged 11-20 years) requiring bilateral extraction of maxillary first premolars were included from the Sydney Dental Hospital waiting list. After premolar extractions, leveling, and alignment, canines were retracted on 0.020-in stainless steel wires with coil springs delivering 150 g of force to each side. Each patient’s right side was randomly assigned to experimental or control using www.randomisation.com , and allocation concealment was performed with sequentially numbered, opaque, sealed envelopes. The experimental side received 850 nm wavelength, 60 mW/cm 2 power, continuous LED with OrthoPulse device (Biolux Research Ltd, Vancouver, British Columbia, Canada) for 5 min/d. For the control side, the device was blocked with opaque black film. Patients were reviewed at 4-week intervals for force reactivation and intraoral scanning over 12 weeks. The primary outcome was the amount of tooth movement, and secondary outcomes were anchorage loss and canine rotation, all measured digitally. Blinding for study participants and the treating clinician was not possible; however, blinding was done for the measurements by deidentifying the digital scans. Linear mixed models were implemented for the data analysis.
Results
Nineteen participants concluded the study. Data analysis showed that the treatment × time interaction was not significant, suggesting no difference in space closure (unstandardized regression coefficient [ b ], 0.12; 95% confidence interval [CI], −0.05 to 0.29; P = 0.17), canine rotation ( b , 0.21; 95% CI, −0.82 to 1.25; P = 0.69), and anchorage loss ( b , −0.01, 95% CI, −0.28 to 0.26, P = 0.94). No harms were noted.
Conclusions
Daily 5-minute application of LED did not result in clinically meaningful differences during extraction space closure compared with no LED application.
Registration
Australian New Zealand Clinical Trials Registry (ACTRN12616000652471).
Protocol
The protocol was not published before trial commencement.
Funding
This research was funded by the Australian Society of Orthodontists Foundation for Research and Education.
Highlights
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Maxillary canine distalization was compared between OrthoPulse and control sides.
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Orthodontic tooth movement was similar in OrthoPulse and control sides.
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Canine rotations and anchorage loss were similar on both sides.
The prolonged duration of orthodontic treatment can be a parameter that is difficult to manage. Orthodontic treatment can last between 15 and 31 months, with the average being around 20 months. , A significant proportion of patients who are interested in receiving orthodontic treatment may find the duration of treatment as a major deterrent. Currently, there has been an increase in demand for methods to reduce orthodontic treatment duration. Shortened treatment times can be beneficial to both the orthodontist and patient. The risk of adverse side effects of orthodontic treatment such as decalcification, root resorption, and periodontal inflammation may be minimized by reducing treatment duration. Improved cost-efficiency and reduced patient noncompliance may also be advantageous. , , For these reasons, the orthodontic literature has seen a recent surge in techniques developed to accelerate tooth movement. These methods may be categorized as pharmacologic, surgical, and appliance-assisted techniques. The mechanism of action behind these methods relies on enhancing the biological systems that are responsible for orthodontic tooth movement. This is because the rate of tooth movement is mainly dependent on the rate of alveolar bone and the periodontal ligament (PDL) remodeling. ,
The ideal intervention to accelerate tooth movement would be an appliance or technique that is easy to use, elicits minimal side effects, and is economical for both the patient and clinician. A noninvasive treatment modality would also be optimal for patient acceptance. Photobiomodulation (PBM) therapy involves the exposure of tissues to the light of the red or near-infrared wavelength. Light is absorbed by cytochromophores in the mitochondria of cells, leading to an increase in adenosine triphosphate and a subsequent increase in cellular energy. , Enhanced cellular metabolism and proliferation are suggested to have the potential to accelerate tooth movement by enhancing osteoblast and osteoclast proliferation and function. The present literature suggests that PBM therapy has the potential to accelerate tooth movement by as much as 30%. , ,
PBM therapy may be carried out by using lasers or light-emitting diodes (LEDs); however, the light produced by each method is inherently different. Currently, there is still debate about whether LED or laser is more appropriate as light sources for PBM therapy. This was due to the initial belief that the coherence of laser light was required to accomplish the therapeutic outcomes of PBM; however, this has been challenged by the recent use of LED in PBM therapy. In addition, lasers require a trained clinician, are bulkier and more expensive compared with LED devices which are safe and easy for patients to use at home. The current level of evidence to support LED-mediated PBM therapy as a treatment modality to accelerate tooth movement is of low quality, , , and further research is required to determine the clinical effectiveness of this intervention in everyday orthodontic practice.
Specific objectives or hypotheses
The primary aim of this clinical trial was to investigate the effect of LED-mediated PBM (850 nm wavelength, 60 mW/cm 2 power, continuous LED with the OrthoPulse device [Biolux Research Ltd, Vancouver, British Columbia, Canada]) applied for 5 min/d on maxillary premolars’ extraction space closure through canine distalization over 12 weeks compared with no PBM. The secondary aims were to evaluate the amount of anchorage loss and canine rotation.
Material and methods
Trial design and any changes after trial commencement
This study was a 2-arm-parallel, split-mouth trial, in which the right side of each patient was randomized to either the experimental or control group and the contralateral side to the other treatment concurrently. There were no changes to the methods after the commencement of the trial.
Participants, eligibility criteria, and settings
Ethics approval was attained by Sydney Local Area Health District, Royal Prince Alfred Hospital Zone Ethics Review Committee (approval nos. X16-0215 and HREC/16/RPAH/266).
The sample consisted of 20 patients (10 males and 10 females), with a mean age of 15.8 years (standard deviation [SD], 2.3 years), who were selected from the orthodontic department waiting list at the Sydney Dental Hospital. Inclusion criteria were (1) requirement of bilateral maxillary first premolar extractions with moderate anchorage as part of the orthodontic treatment; (2) permanent dentition; (3) no previous orthodontic or orthopedic treatment; (4) no significant medical history or medication that would adversely affect the development or structure of the teeth and jaws and any subsequent tooth movement; (5) no craniofacial anomalies or missing teeth; (6) no previous reported or observed dental treatment of the maxillary canines; (7) no impacted canines or canines with severely dilacerated roots; (8) no history of trauma, bruxism, parafunction or periodontal disease. Informed consent was gained from the patient or guardian (if aged under 18 years). Full pretreatment records were taken before any treatment was commenced.
Interventions
All patients had a Nance-transpalatal arch fitted to the second molars for anchorage. Patients then underwent bilateral extraction of maxillary first premolars. Bonding of fixed appliances was then carried out using self-ligating 0.022-inch slot SPEED brackets and tubes (Hanson prescription; Strite Industries, Cambridge, Ontario, Canada). A standardized wire sequence of 0.014-in or 0.016-in nickel-titanium (NiTi) (3M Unitek, Monrovia, Calif) for 8 weeks, 0.018 × 0.018-in 3t Tritanium Memory wire (American Orthodontics, Sheboygan, Wis) for 8 weeks, and 0.019 × 0.025-in beta-titanium molybdenum (3M Unitek) for 8 weeks were used to achieve leveling and alignment. The second premolars and first and second molars were consolidated as a unit using a 0.008-in stainless steel (SS) ligature tie on both sides. Canines were distalized using an 0.020-in SS wire and medium super-elastic NiTi closed coil springs (Orthomax, TOMY International, Burwood, Australia) attached to 5 mm powerarms (0.016 × 0.016-inch SS; Dentarum, Ispringen, Germany) from the canine to the first molars. The force level was 150 g of retraction force measured with a calibrated spring gauge (Dentarum) and checked at each 4-week interval. A minimum of 3 mm space was required distal of the canine, after leveling and alignment and before the commencement of distalization. Patients were instructed to use the OrthoPulse device on the maxillary arch for 5 min/d over the canine retraction period. The manufacturer recommends using the OrthoPulse device for 10 min/d, which corresponds to 5 minutes per arch. As we assessed maxillary extraction space closure, the device was used only in the maxillary dental arch.
The OrthoPulse device is an intraoral PBM device that emits a near-infrared light with a continuous 850 nm wavelength. The device consists of a flexible silicone mouthpiece that contains 54 LEDs spaced 5 mm apart. A power density of 60 mW/cm 2 is produced from the LED array. An individual layer of opaque, black film was used to obstruct the light produced from either the left or right side (defined by the randomization as a sham side) of the LED banks on the OrthoPulse device. A single coating of medical-grade adhesive tape (Leukoflex, BSN medical GmbH Hamburg, Germany) was then used to seal over the black film ( Fig 1 ). The level of light obstruction achieved was tested using a Lasercheck sensor (Lasercheck, Edmund Optics, Barrington, NJ). Complete obstruction of light was affirmed on the sham side. Patient compliance was monitored using the OrthoPulse smart phone application, which uses Bluetooth to log patient use. An 80% compliance level was set as the minimum for inclusion in the study. Review appointments were made every 4 weeks after the commencement of canine retraction, resulting in 4 time points (0 weeks [T0], 4 weeks [T1], 8 weeks [T2], and 12 weeks [T3]). At each time point, intraoral scans of the maxillary arch were taken using a 3D laser scanner (Trios Model 3, 3D Dental Scanner; 3Shape A/S, Copenhagen, Denmark). All interventions and measurements were performed by a sole clinician (S.A).
Outcomes (primary and secondary)
The primary outcome was the amount of tooth movement. The secondary outcomes were canine rotation and anchorage loss. The 3Shape Orthoanalyzer software (version 1.7.1.4; 3Shape A/S) was used to measure all outcomes ( Fig 2 ). Tooth movement was calculated from the changes in the distance between the distal contact point of the canine to the mesial contact point of the second premolar as measured at timepoints (T0-T1, T1-T2, T2-T3, and overall T0-T3). The canine rotation was assessed using the angle between a line formed from the mesial and distal contact points of the canine to the midsagittal plane. The distance along the midsagittal plane from the distal contact point of the second premolar to the most medial point of the third palatal rugae was used to determine anchorage loss. The occlusal plane was used as a reference for these 2 measurements, and it was set by the most occlusal point of the second molars to the incisal tip of the central incisors.
Sample size calculation
The sample size was calculated on the basis of the split-mouth study of Aboalnaga et al. The rate of canine distalization was similar between test and control sides, accounting for 1 mm/mo. An increase of 0.5 mm/mo (SD, 0.7 mm) in the rate of space closure was considered clinically important for calculating the sample size for this trial. To detect such a difference with 80% power and alpha of 0.05, 16 patients were required. To account for dropouts, a total of 20 patients were recruited.
Interim analysis and stopping guidelines
Not applicable.
Randomization (random number generation, allocation concealment, implementation)
A computerized random number generator ( www.randomisation.com ) was used to randomly assign each patient’s right canine to the letter A or B, corresponding to an experimental or sham application. The left side of the patient was then allocated to receiving the alternate procedure, and the LED device was modified accordingly. The allocation ratio was forced to 1:1, and concealment was achieved with opaque, sealed envelopes that included treatment allocation and were created and kept by a person not involved in any clinical contact with the patients.
Blinding
Blinding of patients and the treating clinician was not possible during the experimental period as both could readily view the sham side of the device because of the existence of the obstructing film. Nevertheless, blinding was done for the measurements by deidentifying the digital scans and for statistical analyses.
Statistical analysis
Descriptive statistics of means and SDs were calculated for all variables. Data was visualized overtime per treatment group, and missing data were assessed. Data were assumed to be missing at random because of coronavirus disease 2019 (COVID-19) related inability to attend the clinic. Given the longitudinal structure of the data and the use of the direct likelihood approach, no imputations were deemed necessary. To assess if there was a difference overtime on space closure efficiency, canine rotation, and anchorage loss between treatment groups, random effects linear regression models were fitted with main effects and treatment × time interactions. For the space closure model, a random intercept and random slope (time) were included, whereas for rotation and anchorage loss, only a random intercept. Correlations for all absolute values for primary and secondary outcomes were calculated to inform future sample size calculations and meta-analyses. Repeated measurements of 30% of randomly selected models were performed 3 weeks after initial measurements for calculation of the repeatability. All analyses were conducted using Stata (version 16.1; StataCorp, College Station, TX) and R Software (version 3.6.1; R Foundation for Statistical Computing, Vienna, Austria) with a 2-sided 5% level of statistical significance. The anonymized raw dataset is provided in Zenodo ( Supplementary Data ).
Results
Participant flow
The CONSORT diagram shows the patient flow during the trial ( Fig 3 ). Twenty patients were randomized to treatment and control. One patient dropped out of the research trial before canine retraction because of personal reasons. Nineteen patients received treatments and were included for data analysis in the study, which included 9 females (47%) and 10 males (53%) with a mean age of 15.8 years (SD, 2.3 years; range, 11-20 years). Patients were screened and recruited from December 2018 to August 2019. Two patients missed T0-T1 and T1-T2 intraoral scans because of their inability to attend the clinic during the COVID-19 pandemic. These patients were then subsequently scanned at T2-T3 timepoints. One patient missed the T2-T3 scan because of the canine bracket disengaging from the wire and the inability to re-engage the bracket in a timely manner during the COVID-19 pandemic. One patient missed T1-T2 and T2-T3 scans for the same reason. One patient missed T1-T2 and T2-T3 scans because of refusal to continue using the intraoral appliance. The LED and control groups had similar initial values at T0 for the distance between contact points, canine rotation, and anchorage situation. Given the split-mouth approach, repeated measures design, high correlations were expected for the within-patient measurements between quadrants and across time points. Those correlations ranged from 0.81-0.92, 0.61-0.81, 0.67-0.73 for space closure, canine rotation, and anchorage loss, respectively
