正畸力本身随着力的大小、方向及着力点的不同,而产生不同的效应。力的大小决定牙齿移动的量,着力点和力的方向则决定牙齿移动的方式。根据物理学原理,当一个以上的力作用于一颗牙上时,牙按照诸力的合力移动。而任何作用于牙上的力又可分解为垂直及平行于咬合面的分力。这样来确定牙齿在水平及垂直方向移动的量。牙齿本身可作为一个刚体来考虑,但牙又是通过牙周膜与齿槽骨相连接,它的移动受到周围组织的阻力及生物体允许的限度所 Orthodontic force itself with the strength of the size, direction and focus of different points, and have different effects. The size of the force determines the amount of tooth movement, the point of exertion and the direction of the force determine the way the tooth moves. According to the principle of physics, when more than one force acts on a tooth, the tooth moves in accordance with the combined efforts. And any force acting on the teeth can be decomposed into vertical and parallel to the force component of the occlusal surface. This determines the amount of tooth movement in the horizontal and vertical directions. The tooth itself can be considered as a rigid body, but the tooth is connected to the alveolar bone through the periodontal ligament and its movement is limited by the resistance of the surrounding tissue and by the organism