Jacobson A
Am J Orthod. 1979 Apr;75(4):361-86. doi: 10.1016/0002-9416(79)90159-3.
By following certain basic principles, the effects, advantages, and disadvantages of the wide assortment of extraoral assemblies marketed are easily understood. The key to this understanding is the appreciation of the relationship of the line of action of the force application to the center of resistance of the tooth. These principles are discussed in three planes of space: sagittal, coronal, and transverse. Because of the many variables and complexity of mathematically computing the force effects of unilateral or asymmetric extraoral assemblies on molar teeth, a mechanical testing apparatus was designed to accommodate the various face-bows. Not all the designs proved effective, and many of the clinical side effects of the respective face-bow designs became manifest on mechanical testing.
通过遵循某些基本原则，市场上销售的各种口外矫治器的作用、优点和缺点就很容易理解。理解的关键在于认识到施力作用线与牙齿阻力中心之间的关系。这些原则在三个空间平面中进行讨论：矢状面、冠状面和横断面。由于单侧或不对称口外矫治器对磨牙的力效应进行数学计算存在诸多变量和复杂性，因此设计了一种机械测试装置来适配各种面弓。并非所有设计都被证明有效，并且各种面弓设计的许多临床副作用在机械测试中显现出来。
