Vibration in the form of High Frequency Acceleration (HFA) is anabolic on the craniofacial skeleton in the absence of inflammation. Orthodontic forces trigger an inflammation-dependent catabolic cascade that is crucial for tooth movement. It is unknown what effect HFA has on alveolar bone if applied during orthodontic treatment. The objectives of this study are to examine the effect of HFA on the rate of tooth movement and alveolar bone, and determine the mechanism by which HFA affects tooth movement. Adult Sprague Dawley rats were divided to control, orthodontic force alone (OTM), and different experimental groups that received the same orthodontic forces and different HFA regimens. Orthodontic tooth movement was assessed when HFA parameters, frequency, acceleration, duration of exposure, and direct or indirect application were varied. We found that HFA treatment significantly enhanced the inflammation-dependent catabolic cascade during orthodontic tooth movement. HFA treatment increased inflammatory mediators and osteoclastogenesis, and decreased alveolar bone density during orthodontic tooth movement. Each of the HFA variables produced significant changes in the rate of tooth movement and the effect was PDL-dependent. This is the first report that HFA enhances inflammation-dependent catabolic cascades in bone. The clinical implications of our study are highly significant, as HFA can be utilized to enhance the rate of orthodontic tooth movement during the catabolic phase of treatment and subsequently be utilized to enhance retention during the anabolic remodeling phase after orthodontic forces are removed.

Mechanical stimulation contributes to the health of alveolar bone, but no therapy using the osteogenic effects of these stimuli to increase alveolar bone formation has been developed. We propose that the application of high-frequency acceleration to teeth in the absence of significant loading is osteogenic. Sprague-Dawley rats were divided among control, sham, and experimental groups. The experimental group underwent localized accelerations at different frequencies for 5 min/day on the occlusal surface of the maxillary right first molar at a very low magnitude of loading (4 µε). Sham rats received a similar load in the absence of acceleration or frequency. The alveolar bone of the maxilla was evaluated by microcomputed tomography (µCT), histology, fluorescence microscopy, scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR imaging), and RT-PCR for osteogenic genes. Results demonstrate that application of high-frequency acceleration significantly increased alveolar bone formation. These effects were not restricted to the area of application, and loading could be replaced by frequency and acceleration. These studies propose a simple mechanical therapy that may play a significant role in alveolar bone formation and maintenance.

A common problem in clinical dentistry is the significant and rapid bone loss that occurs after tooth extraction. Currently there is no solution for the long-term preservation of alveolar bone. Previously, we showed that high-frequency acceleration (HFA) has an osteogenic effect on healthy alveolar bone. However, it is not known if HFA can preserve alveolar bone after extraction without negatively affecting wound healing. The purpose of this study was to evaluate the effect of HFA on alveolar bone loss and the rate of bone formation after tooth extraction. Eighty-five adult Sprague-Dawley rats were divided into 3 groups: control, static (static load), and HFA. In all groups, the maxillary right third molar was extracted. The HFA group received HFA for 5 min/d, applied through the second molar. The static group received the same magnitude of static load. The control group did not receive any stimulation. Some animals received fluorescent dyes at 26 and 54 d. Samples were collected on days 0, 7, 14, 28, and 56 for fluorescence microscopy, micro–computed tomography, histology, RNA, and protein analyses. We found that HFA increased bone volume in the extraction site and surrounding alveolar bone by 44% when compared with static, while fully preserving alveolar bone height and width long-term. These effects were accompanied by increased expression of osteogenic markers and intramembranous bone formation and by decreased expression of osteoclastic markers and bone resorption activity, as well as decreased expression of many inflammatory markers. HFA is a noninvasive safe treatment that can be used to prevent alveolar bone loss and/or accelerate bone healing after tooth extraction.