High Frequency Acceleration: A New Tool for Alveolar Bone Regeneration.

INTRODUCTION: A common problem in clinical dentistry is the significant and rapid bone loss that occurs after periodontitis, osteoporosis, tooth extractions, lack of function, or any other pathologic condition that target the alveolar bone. Currently there is no stable solution for the long-term preservation or rehabilitation of alveolar bone. In this article, we review the latest concepts on bone response to mechanical stimulation, and summarize the results of our studies on the effect of high frequency acceleration (HFA) on healthy alveolar bone and on healing alveolar bone after extractions. METHODS: In both studies, we used adult Sprague Dawley rats to test the response of alveolar bone to different frequencies and accelerations applied to the maxillary molars. RESULTS: Once we determined which parameters of HFA induced a higher osteogenic response, we tested the effect of this mechanical stimulation during bone healing after molar extraction. Our studies strongly show that HFA can stimulate bone formation in the healthy alveolar bone surrounding the tooth/point of application as well as the distant bone surrounding the neighboring teeth. When HFA was applied to the second molar, after extraction of the third molar, it accelerated bone healing and prevented alveolar bone resorption in and around the extraction socket. CONCLUSION: HFA is a noninvasive safe treatment that can be used to prevent alveolar bone loss, accelerate bone healing and to improve the quality and quantity of alveolar bone under both physiological and pathological conditions.

High-Frequency Acceleration: Therapeutic Tool to Preserve Bone following Tooth Extractions.

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.

Saturation of the biological response to orthodontic forces and its effect on the rate of tooth movement.

OBJECTIVES: Investigate the expression and activity of inflammatory markers in response to different magnitudes of orthodontic forces and correlate this response with other molecular and cellular events during orthodontic tooth movement. SETTING AND SAMPLE POPULATION: CTOR Laboratory; 245 Sprague Dawley male rats. METHODS AND MATERIALS: Control, sham, and 5 different experimental groups received different magnitudes of force on the right maxillary first molar using a coil spring. In the sham group, the spring was not activated. Control group did not receive any appliance. At days 1, 3, 7, 14, and 28, the maxillae were collected for RNA and protein analysis, immunohistochemistry, and micro-CT. RESULTS: There was a linear relation between the force and the level of cytokine expression at lower magnitudes of force. Higher magnitudes of force did not increase the expression of cytokines. Activity of CCL2, CCL5, IL-1, TNF-α, RANKL, and number of osteoclasts reached a saturation point in response to higher magnitudes of force, with unchanged rate of tooth movement. CONCLUSION: After a certain magnitude of force, there is a saturation in the biological response, and higher forces do not increase inflammatory markers, osteoclasts, nor the amount of tooth movement. Therefore, higher forces to accelerate the rate of tooth movement are not justified.