Use of laser therapy to modify OTM was introduced in 2000 by Kawasaki and Noriyoshi. Using a Ga-Al-As diode laser, OTM in rats was 1.3 times greater than controls with an increase of osteoblasts on the tension side and osteoclasts on the compression side. The laser specifications were 830 nm continuous wavelength and 100mW power used for three minutes at three sites around the experimental tooth.8 Several other studies have been conducted in humans subsequently, demonstrating 1.34 to 2 times the rate of OTM following laser treatment9-11 and reduced pain perception.11 Biological changes have been determined to be increases in osteoblast and osteoclast proliferation, resulting in increased bone remodeling and OTM.12 Sousa et al. hypothesized a mechanism of increased adenosine triphosphate and thus cell metabolism.13 Shirazi et al. used an alternative In-Ga-Al-P laser in rats, showing 2.3 times the amount of OTM and 1.5 times more osteoclasts on the compression side compared to controls.14
While one study among the extensive literature showed no effect on OTM rate using laser,15 the majority of studies have shown positive effects in both animal and human models. Conversely, some recent studies have shown that laser therapy failed to accelerate OTM.16,17 Some considerations may be the type of laser, frequency, and technique, as well as type of tooth movement attempted. While this technique is being investigated, a high level of evidence is still lacking to conclude whether or not this technique is effective in accelerating OTM and what procedure may be the most effective. Properly understanding the mechanism behind the acceleration of OTM with laser therapy may provide an improved understanding of the procedure and encourage practitioners to try it in their practices.
Light Emitting Diode (LED) has been used as an alternative form of photobiomodulation. It has been claimed as less coherent than low level laser therapy and less prone to root resorption. In rats, 0.49mm more OTM was seen over a 3-week period with decreased amounts of root resorption.18 Another study evaluating canine retraction in human subjects found faster OTM in those using this technology.19 The OrthoPulse® LED device has been developed by Biolux and FDA approved for application of LED in orthodontic patients to help accelerate OTM.