Southard Thomas E, Marshall Steve D, Grosland Nicole M
Department of Orthodontics, University of Iowa, Iowa City, Iowa 52246, USA.
Am J Orthod Dentofacial Orthop. 2007 Mar;131(3):412-4. doi: 10.1016/j.ajodo.2006.09.037.
Conventional wisdom suggests that orthodontists must apply added force to overcome friction during canine retraction (sliding mechanics), the result of which can be increased anchorage loading and anchorage loss. However, for a frictional force to be exerted mesially by the archwire against a canine during retraction, the archwire must be compressed between the canine and the anchor molar, and an equal but opposite force must be applied distally against the molar by the archwire. In other words, the frictional force that reduces the force of retraction on the canine must also reduce the protraction force on the molar. Emphasis on employing reduced-friction (eg, self-ligating) brackets during sliding mechanics to prevent added posterior anchorage loading is unwarranted and based more on bracket salesmanship than on orthodontic biomechanics.
传统观念认为，正畸医生在犬齿后移（滑动矫治技术）过程中必须施加额外的力来克服摩擦力，其结果可能会增加支抗负荷和支抗丧失。然而，在犬齿后移过程中，弓丝要向近中方向对犬齿施加摩擦力，就必须在犬齿和支抗磨牙之间对弓丝进行压缩，并且弓丝必须向远中方向对磨牙施加一个大小相等、方向相反的力。换句话说，降低犬齿后移力的摩擦力也必然会降低磨牙的前移力。在滑动矫治技术中强调使用低摩擦（如自锁）托槽以防止额外的后牙支抗负荷是没有必要的，更多是基于托槽的推销，而非正畸生物力学原理。
