The Effect of Low Level Laser Therapy on the Rate of Tooth Movement and Pain Perception during Canine Retraction

Keywords:surgical, fibers,  Time:21-04-2016
Although these methods showed successful results in some studies, they have their own disadvantages such as painful injection and dependence on a special apparatus which should be modified for this application and may also require frequent applications to induce the desirable effect. Non-steroidal anti-inflammatory drugs, which are usually used to decrease pain resulted from activation of orthodontic appliances, may be associated with deleterious health effects and may also reduce orthodontic tooth movement [9]. Therefore, finding an optimum supplementary approach to achieve faster tooth movement and decrease pain is still considered as a subject of interest.

Low Level Laser Therapy (LLLT) is a simple and inexpensive method that can be used easily in the dental practice for different purposes such as pain reduction [10], enhancement of wound healing [11] and alleviating inflammation [12]. Some studies investigated the efficacy of low power lasers in reducing pain during orthodontic treatment [12,13], promoting bone regeneration in the midpalatal suture during expansion [14] and stimulating tooth movement. The results of studies on the rate of tooth movement are controversial. Some animal and human studies reported a significant acceleration of tooth movement in the laser group compared to the placebo application [15-17], but others reported no difference [18-20] or even indicated the inhibitory effect of laser therapy on the rate of tooth movement [21]. One of the problems that clinicians frequently encounter is tipping of canine teeth during retraction. The type of tooth movement (bodily versus controlled tipping) affects the degree of mesiodistal angulation of the tooth and may have a remarkable effect on the final esthetics of the treatment. It can be assumed that by changing the remodeling rate and alveolar bone resistance during canine retraction, it would be possible to affect the degree of tooth tipping. The purpose of this study was to determine the effect of a gallium-aluminum-arsenide (GaAlAs) low-power laser on pain perception, the magnitude of movement and the degree of mesiodistal inclination of canines during retraction.

Materials and Methods

The sample consisted of twenty patients (3 male, 17 females) attending for orthodontic treatment in a private office. The patients were ranged in age from 15 to 31 years (mean age 22.1 ± 5.3 years). Based on complete orthodontic records, the treatment plan of all patients included extraction of upper first premolars with/without mandibular premolar extraction. Patients who had any systemic diseases and those with periodontally compromised teeth as well as subjects who were under medications that could interfere with tooth movement such as anti-inflammatory drugs were excluded from the study. The study design was approved by the Ethics Committee of Mashhad University of Medical Sciences. The research protocol was described clearly for the patients and an informed consent was obtained from each participant or his/her legal responsible before the commencement of the treatment.

Orthodontic treatment

The orthodontic treatment was performed with 0.018-in preadjusted edgewise appliances (Roth prescription; Dentsply GAC International, Bohemia, NY, USA). After complete leveling and aligning, which lasted for at least 3 months after appliance placement, the canine teeth on both sides were retracted through a 0.016-inch SS wire (Dentaurum, Ispringen, Germany). A vertical loop (3 mm) was incorporated in the mesial of each molar tube to serve as the posterior stop for anchorage reinforcement. The canines were tied to the arch wire with 0.010-in steel ligature wires to reduce tooth rotation during retraction. The central and lateral incisors were also consolidated with ligature wires. Canine retraction was accomplished by Ni-Ti closed coil springs with length of 9 mm (0.011×0.030-in, Ortho Technology, Tampa, Florida, USA). The spring was attached to the hook of the first molar by a stainless steel ligature wire, then stretched to give 150 g of force and secured to the canine with a second ligature wire. A force gauge (Dentaurum, Pforzheim, Germany) was used to determine that the 150 g traction force is delivered.

The spring was adjusted 28 days later to give the same force value (150 g). Immediately before starting canine retraction (T0), an alginate impression was taken from the maxillary arch to provide an initial dental model. This model also served as a base for a custom tray made from putty impression material (Speedex, Coltene, Alstatten, Switzerland). The retention and undercuts of the tray were then filled with sticky wax and the final impression of the upper arch was taken using a silicon wash (Speedex, Coltene). This final impression was poured with Vel-Mix stone (Kerr Co, Orange, CA, USA) to increase the precision of measurements. At the follow-up intervals of 28 (T1) and 56 (T2) days, the process of taking impression was repeated to allow measuring the changes occurred in the canine position during treatment.