The difference in these treatment outcomes is controversial and still unclear. Although some of these studies reported an increase in the rate of tooth movement when vibration was applied as an adjunct to orthodontic treatment 8, others demonstrated that supplemental vibration did not increase the rate of tooth movement 9, 10. In dental practice, several prospective randomised controlled clinical trials have recently investigated the effect on orthodontic tooth movement of supplemental vibration applied with fixed appliances for 20 min/day using a vibration device which delivers a force of 0.25 N (25.49 g) at a frequency of 30 Hz to the dentition 8– 10. LMHF vibration is currently used as a safe and non-invasive treatment for bone loss in postmenopausal women 21 and also to promote osteogenesis in children with disabling conditions 22. Low-magnitude (LM less than 1 g, where g = 9.81 m/s 2) high-frequency (HF 20–90 Hz) vibrations, such a mechanical signal, can positively influence skeletal homeostasis and stimulate an anabolic response in both weight-bearing 18 and non-weight-bearing 19 bone, and furthermore, in adult rats with ovariectomy-induced osteoporosis 20. However, adverse side effects such as local pain, discomfort and severe root resorption 17 have been associated with these techniques. Attempts to accelerate tooth movement to shorten the duration of treatment by stimulating the remodelling activity of alveolar bone have included physical approaches (such as low-energy laser irradiation 6, low intensity pulsed ultrasound 7, vibration 8– 10 and pulsed electromagnetic fields 11) and pharmaceutical approaches (such as local injection of prostaglandin E 2 12, 1,25-dihydroxyvitamin D 3 13– 15 and parathyroid hormone 16). However, orthodontic treatment is often of long duration, is accompanied by risks such as dental caries and periodontal disease, and induces pain, discomfort 1, 2 and root resorption 3– 5.
Orthodontic treatment can enhance the quality of life of patients with malocclusion by improving aesthetics, stomatognathic function, and psychological disorders. These findings contribute to a better understanding of the mechanism by which optimum-magnitude high-frequency vibration accelerates tooth movement, and may lead to novel approaches for the safe and effective treatment of malocclusion. Furthermore, at this optimum-magnitude, high-frequency vibration could synergistically enhance osteoclastogenesis and osteoclast function via NF-κB activation, leading to alveolar bone resorption and finally, accelerated tooth movement, but only when a static force was continuously applied to the teeth. The most effective level of supplementary vibration to accelerate tooth movement stimulated by a continuous static force was 3 gf at 70 Hz for 3 minutes once a week. In the present study, we developed a new vibration device for a tooth movement model in rats, and investigated the efficacy and safety of the device when used with fixed appliances. This technique is still controversial, and the underlying cellular and molecular mechanisms remain unclear. Among them, some studies reported an increase in the rate of tooth movement, but others did not. Several recent prospective clinical trials have investigated the effect of supplementary vibration applied with fixed appliances in an attempt to accelerate tooth movement and shorten the duration of orthodontic treatment.
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