STUDY FOR EFFECTS OF MANDIBULAR DISTRACTION OSTEOGENESIS IN TMJ

下颌骨头部呈软骨生长，被认为是下颌骨生长区域中数量最多的。CT和头颅造影显示该部位软骨生长形态多样，其评估被认为是预测生长的关键。影响关节头生长的刺激因素包括咀嚼时产生的反作用力。近年来，在临床正畸治疗中，牵张成骨被用于治疗骨骼不和谐的发展。然而，髁状突力学状况变化的细节尚不清楚。在本研究中，我们观察了生长大鼠下颌牵张成骨的髁突生长情况，并计算了每个个体咀嚼肌分数和牙负荷的矢量在关节头产生的反作用力矢量。通过动物实验，检测了髁突软骨PTHrP的变化。在临床评估结果中，我们还使用压力传感器片确定了牙列的加载位置和负载。然后我们在每个受试者的CT图像中确定肌肉牵引的方向和牙齿载荷的方向，从每个载荷的二维位置、积分和咬合压力确定的矢量中计算力矩，并计算关节头部产生的相反力。由咀嚼肌牵引矢量计算的反作用力矢量和牙负荷受牵张负荷的影响。特别是当咬合力改变时，反作用力发生倾斜。我们正在分析向量的维度和增长的数量，我们希望这种方法可以预测分心的方向。

The mandibular head shows cartilaginous growth, and the growth at this site is considered to be the greatest quantitatively among the growth areas of the mandible. Cartilaginous growth at this site shows diverse morphology by CT and cephlography, and its evaluation is considered to be a key to growth prediction. Stimulatory factors that affect the growth of the joint head include the reaction force generated in mastication. Recently, in clinical orthodontics, distraction osteogenesis is performed for development of skeletal disharmony. However, details in the changes of mechanical condition at condyle is still unknown.In this study, we examined condylar growth with mandibular distraction osteogenesis with growing rats, also calculated the vector of the reaction force generated at the joint head from the vectors of masticatory muscle fraction and dental loads in each individual. From the resultant of animal experiment, the change on PTHrP was detected at condylar cartilage. In the result of clinical evaluation, we also determined the loading sites in the dentition and the loads using pressure-sensor sheets. We then determined the direction of muscle traction and direction of dental loading in the CT image of each subject, calculated the moments from vectors determined by the two dimensional position of each load, its integral, and occlusal pressure, and calculated the opposite force generated at the joint head. The vector of the reaction force calculated from the traction vectors of masticatoly muscles and dental loads was affected by distraction load. Particularly, the reaction force was inclined when the occlusal force was changed. We are analyzing the dimension of the vector and the quantity of growth, and we expect this method to make prediction of the direction of distraction possible.