Clinical application of shockwave therapy in orthodontics

Abstract

Extracorporeal shockwaves are noninvasive mechanical forms of sound wave treatment. They were introduced in medical therapy approximately 30 years ago in order to disintegrate kidney stones. Over the last 15 years, extracorporeal generated shockwaves have been used in many fields of medicine due to their versatility and ability to stimulate healing processes by inducing neovascularization and differentiate stem cells into cells of the injured tissue to allow proper healing and regeneration. Orthodontic tooth movement is a model that includes the induction of aseptic inflammation and its resolution. Since extracorporeal shockwave therapy (ESWT) can modulate healing processes, it might have an effect on orthodontic tooth movement. This hypothesis was recently studied in a rat model, in which rats were treated with ESWT in conjunction with orthodontic force commencement. After 3 days of force application, the concentration of all tested cytokines in the shockwave-treated group was smaller compared to the non-treated; however, a statistically significant difference was found only in regard to sRANKL. The anti-inflammatory effect and the positive effect of ESWT on bone formation are reflected in these results. After 3 weeks of force application, the addition of ESWT to the orthodontic force further stimulated tooth movement by 45% when measured by microcomputed tomography. On the pressure side, the application of orthodontic force along with ESWT induced a significant decrease in volumetric bone mineral density, whereas orthodontic force alone did not. On the tension side, according to the accelerated tooth movement, a difference was observed in the newly formed bone between the groups. These findings indicate that the induction of shockwave therapy during orthodontic tooth movement alternates the expression of different inflammatory cytokines in the PDL. This change might have been the cause of the increase in the rate of tooth movement by accelerating bone resorption on the pressure side and possibly enhancing bone formation on the tension side. Thus, ESWT might have a positive effect on bone turnover.