Development of mechanics of efficient tooth movement for reduction of orthodontic treatment period

控制前牙的运动对正畸治疗的成功至关重要。在滑动力学中，通过将不同长度的动力臂焊接到拱丝上，可以自由调节水平的收缩力。因此，可以简单地应用所需类型的齿运动的力系统。本研究的目的是确定什么水平的内收力，即什么长度的动力臂允许前牙内收到所需的位置。选择具有右上中切牙的人类受试者作为目标牙。采用两点三维位移磁传感器装置测量了在不同水平收放力作用下的滑动力学作用下齿的初始运动。传感器实时检测并记录目标牙的初始位移。研究了牙在矢状面上的运动轨迹。结果表明，目标牙的旋转中心位置随施加回缩力的高度而变化。因此，可以通过控制旋转中心的位置，或者是施加回缩力的高度水平，即动力臂本身的长度，使前牙沿预定的路线向冠-舌或根-舌倾斜。这将有助于正畸医师为患者制定有效的治疗计划。

Control of anterior teeth movement is essential to the success of an orthodontic treatment. In Sliding Mechanics, horizontal level of retraction force can be freely adjusted by soldering various lengths of power arms to an arch wire. Therefore, the force system for desired type of tooth movement can be simply applied. The purpose of this study was to determine what level of retraction force, namely, what length of power arm allow the anterior teeth to retract to a desired position. Human subject with upper right central incisor was chosen as target tooth. Initial tooth movement under sliding mechanics with various horizontal retraction forces were measured by Two-point Three-Dimensional Displacement Magnetic Sensor Device. The sensors detected and recorded initial displacement of target tooth in real time. The tooth's motion trajectories projected on the sagital plane was studied. It was suggested that the location of center of rotation of the target tooth varies according to the height level of retraction force application. Therefore, anterior tooth can be tipped crown-lingually or root-lingually in a pre-determined course by manipulating the location of center of rotation or rather the height level of retraction force application, i.e. the length of power arms itself. This would be of great help to orthodontists for establishing efficient treatment planning for patients.