Gauri Doshi-Mehta and Wasundhara A. Bhad-Patil
What did the authors aim to do in this study?
The primary aim of this study was to evaluate the efficacy of low-intensity laser therapy in reducing orthodontic treatment duration & pain.
How did the authors evaluate?
The sample for this study consisted of 20 healthy orthodontic patients aged around 12 - 23 years old. Patients with a history of long-term medication were excluded because nonsteroidal anti-inflammatory drugs and hormone supplements are known to interfere with the bone metabolism. Patients with unilateral chewing or parafunctional habits, skeletal crossbite, and occlusal interferences were also excluded. Periodontally compromised patients were excluded because poor bone quality can affect orthodontic tooth movement, and the development of mobility can lead to incorrect measurement of orthodontic tooth movement. Impacted canines and canines with dilacerated roots were excluded from the study because dilacerated roots make orthodontic tooth movement difficult with a greater possibility of root resorption.
Routine orthodontic diagnostic records were collected and analyzed for all subjects. The treatment plans for these patients included extraction of the maxillary or mandibular first premolars (or both) to meet the requirements of space for the retraction of the anterior teeth. A randomly assigned incomplete block split-mouth design was used to prevent interindividual biologic variation. In all the 20 patients, the maxillary first premolars were extracted, but the mandibular first premolars were extracted in only 10 patients. In each patient, the extracted right and left quadrants were randomly divided into 2 groups. The patients were blinded about the experimental and control sides. Group 1 was the control side quadrant and did not receive any low-intensity laser therapy. Group 2 was the experimental side quadrant and received laser therapy. Each group consisted of 30 quadrants. On day 7, after the extractions, separators were placed mesially and distally to the first molars for the band placement. After 2 days of separator placement, molar bands were custom made & placed. Transpalatal arch 20-gauge (0.9 mm) stainless steel wire was adapted on the model. Maxillary bands with a transpalatal arch inserted in the lingual sheath were cemented with glass ionomer luting cement. The transpalatal arch was placed for anchorage reinforcement and secured with an elastic module. Individual canine retraction by a nickel-titanium closed-coil spring was studied. A constant force of 150 g was used for canine retraction on both the control and experimental sides. The experimental side received infrared radiation from a semiconductor (aluminium gallium arsenide) diode laser with a wavelength of 810 nm. The laser regimen was applied on days 0, 3, 7, and 14 in the first month, and thereafter on every 15th day until complete canine retraction was achieved on the experimental side.
Tooth movement was measured on progress models. Each patient’s pain response was ranked according to a visual analog scale.
What did the authors find?
The study stated that there was a highly significant positive difference in the rates of tooth movement on the experimental side compared with the control side. The mean increase in the rates of tooth movement at 3 months was 54% in the maxillary arch and 58% in the mandibular arch. Mean increase in the rate of tooth movement after canine retraction was 29% in the maxillary arch and 31% in the mandibular arch. There was a nonsignificant rise in the pain score on the control side, but there were highly significant decreases in the pain scores on the experimental sides. On day 30, there was a highly significant decrease in the pain score on both sides. The pain score on the experimental side was significantly lower compared with the control side on day 3 as well as on day 30.
What did the authors conclude?
Low-intensity laser therapy increases the rate of orthodontic tooth movement in a physiologic manner. It causes no side effects on the vitality or the periodontium of the teeth. Thus, it can safely and routinely be used during orthodontic treatment to shorten the treatment time.
Low-intensity laser therapy also is an effective method of analgesia during orthodontic treatment.
It can be used for differential movement of teeth. In cases of midline shift, it can be used to stimulate orthodontic tooth movement on the opposite side.
Application of low intensity laser therapy only on teeth to be moved conserves the anchorage. Because low-intensity laser therapy stimulates tooth movement by altering the biologic response and not by increasing forces or changing mechanics, it does not tax the anchorage.
What do we think about it?
The most important question that every patient asks an orthodontist is the amount of time the treatment is going to take. Although, the average time required for fixed appliance therapy is around 20 to 30 months, most patients find this very long. So, in order to reduce the amount of treatment time, there is a need to increase the rate of orthodontic tooth movement. Among the various methods available to increase the tooth movement, the simplest and easily available option in the dental clinic is the use of lasers. Low - intensity laser therapy is found to increase the osteoblastic & osteoclastic activity after its application both in studies that are conducted in-vivo & in-vitro. Although, there were drawbacks found in this study, such as no specific blinding procedure was carried out, resulting in a greater percentage of bias during the study. Apart from this, even the laser application was carried out only in a specific area for a specific period of time, and so it cannot generalise the effect present over the whole treatment period or for the entire dentition. Even though all these factors are present, this study gives immense proof of lasers having an effect on the rate of orthodontic tooth movement & also the analgesic effect it has during the orthodontic therapy.
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