Wallis C, Vasir N S, Waters N E
Orthodontic Department, University College London Hospitals, UK.
Br J Orthod. 1998 Nov;25(4):263-7. doi: 10.1093/ortho/25.4.263.
A modification to the standard quadhelix transpalatal expansion arch is presented in which the wire passes distal to the most posterior molar and enters the mesial end of the headgear tube. Laboratory measurements were carried out on small, average and large sized appliances with this modification using a special rig fitted with strain gauges. For the three sizes of appliance, the modified quadhelix is more flexible than the standard quadhelix for both displacement and rotation of the molar arms. Also it is less time consuming to fit and remove it is concluded that this appliance is capable of producing clinically useful forces and couples with increased precision.
本文介绍了一种对标准四螺旋扩弓矫治器的改良方法，改良后的矫治器钢丝绕过最后一颗磨牙的远中并进入头帽管的近中端。使用配有应变片的特殊装置，对采用这种改良方法制作的小、中、大三种尺寸的矫治器进行了实验室测量。对于这三种尺寸的矫治器，改良后的四螺旋矫治器在磨牙臂的位移和旋转方面比标准四螺旋矫治器更灵活。此外，安装和拆卸所需时间更少，得出的结论是，这种矫治器能够产生临床上有用的力和力矩，且精度更高。
