Development and clinical use of measurement system of mandibular bone density without using X-ray

骨振动分析系统用于骨质疏松症筛查的研究目的。本研究的目的是将该系统应用于下颌骨，制作无X线的下颌骨密度测量系统，并验证其临床应用的可能性。将恒定频率（fc）转换为骨的硬度，并预测下颌骨的成熟度和内部结构。通过手持式FFT分析仪和个人计算机自动进行数据采集、频率分析和fc的计算。评价身高、体重、骨密度值、下颌骨形状等生长指标与下颌骨fc的关系，结果如下：1）fc与身高、体重无显著相关性; 2）fc与腕部骨密度有显著相关性; 3）下颌骨的大小，尤其是下颌升支的高度，前牙槽骨高度和联合厚度与X线头影测量结果有显著性差异结果表明，该系统测量的参数可作为评价下颌骨形态和骨质量的新指标。这将导致应用，如骨成熟度的评估，预测生长潜力的指标，通过正颌外科手术的愈合过程，正畸治疗中牙齿移动的支抗价值。

The vibration analyzing system of the bone is used for the research purpose of screening osteoporosis. The purpose of this study was to apply this system to the mandible and fabricate the measurement system of mandibular bone density without using X-ray and check its possibility for the clinical use.Vibration of the mandible was produced through the procedures of setting the chin on the pick up sensor and hit the forehead by the hammer antomatically. The constant frequency (fc) was converted as a hardness of the bone, and the maturity and inner structures of the mandible were predicted. The data taking, frequency analysis and the calculation of the fc were automatically carried out by the hand-held FFT analyzer and the personal computer. The relationship between the growth indicators such as a body height, body weight, value of bone mineral density and the shape of the mandible, etc.and the fc of the mandible were evaluated.The results were as follows :1)The fc did not show the significant relationship with a body height and weight.2)The significant relationship was found between the fc and bone mineral density of the wrist bone.3)The size of the mandible, especially the ramus height, anterior alveolar height and the thickness of the symphysis showed the significance according to the cephalometric evaluation.4)The fc demonstrated the tendency that was higher at the Skeletal Class III and a short face.The results suggest that the parameters measured by this system might be used as the new indicators to evaluate the shape of the mandible and quality of the mandibular bone. This would lead the applications such as the evaluation of bone maturity, the indicators to predict the growth potentiality, healing procedure through the orthognathic surgery, the anchorage value for the teeth movement in orthodontic treatment.