A study on a computerized support system for orthodontic treatment

正畸治疗必须在几年的时间内对患者进行，这取决于正畸医生的经验和技能。我们已经研究了一个计算机化的正畸治疗支持系统的可行性，并证明了巨大的潜力，以优化治疗过程。(1)一个计算机化的治疗计划系统已经开发出来，它允许一个治疗师在计算机图形显示器上构建一个设置模型。该系统是基于我们以前开发的装置获得的牙模型轮廓数据的3D运动。使用该系统，牙科医生可以在治疗前定量预测每个牙齿的3D运动。(2)我们还开发了一个系统，在治疗和正畸力的3D牙齿移动的基础上重新调整正畸矫治器。力的大小和方向，包括由反旋转和山形墙弯曲引起的动量，通过有限元法（FEM）获得。(3)我们估计了患者牙槽骨的吸收率。该速率从牙齿、牙周膜和牙槽骨的有限元模型计算的3D牙齿移动和应力分布获得。再吸收与应力密切相关，约为4 mum/g/mm^2/天。(4)并将该系统应用于上下牙距离分布的测量，以评价咬合接触。在治疗过程中，咬合接触面积增加。该结果验证了该系统作为治疗评价手段的有用性。

Orthodontic treatment must be conducted over a period of a few years on a patient, depending on experience and skill of an orthodontist. We have studied feasibility of a computerized support system for orthodontic treatment and demonstrated enormous potentialities to optimize a treatment procedure.(1) A computerized planning system for the treatment has been developed, which allows an orthodontist to construct a setup model on a computer graphic display. This system is based on the 3D movements of dental cast profile data obtained by our apparatus previously developed. Using this system an orthodontist can predict quantitatively the 3D movement of each tooth prior to the treatment. (2) We have also developed a system to readjust an orthodontic appliance on the basis of 3D tooth movements during the treatment and orthodontic forces. The magnitude and direction of the forces, including the momentum caused by anti-rotation and gable bends, are obtained by a finite element method (FEM). (3) We estimated a resorption rate of alveolar bone on patients. The rate was obtained from both the 3D tooth movement and the stress distribution calculated with a FEM model of a tooth, periodontal membrane and alveolar bone. The resorption was correlated well with the stress and was found to be about 4 mum/g/mm^2/day. (4) To evaluate the occlusal contact the system was also applied to the measurement of distance distribution between upper and lower teeth. The occlusal contact area increased during the treatment. This result verifies the usefulness of the system as a mean of treatment evaluation.