Department of Mechanical Engineering, Faculty of Engineering, University of Alberta, Edmonton, Alberta, Canada.
Am J Orthod Dentofacial Orthop. 2011 Sep;140(3):326-39. doi: 10.1016/j.ajodo.2010.07.024.
Control of root torque is often achieved by introducing a twist in a rectangular archwire. The purpose of this study was to investigate third-order torque on different types of self-ligated brackets by analyzing the bracket's elastic and plastic deformations in conjunction with the expressed torque at varying angles of twist.
An orthodontic bracket was mounted to a load cell that measured forces and moments in all directions. The wire was twisted in the bracket via a stepper motor, controlled by custom software. Overhead images were taken by a camera through a microscope and processed by using optical correlation to measure deformation.
At the maximum torquing angle of 63° with 0.019 × 0.025-in stainless steel wire, the total elastic and plastic deformation values were 0.063, 0.033, and 0.137 mm for Damon Q (Ormco, Orange, Calif), In-Ovation R (GAC, Bohemia, NY), and Speed (Strite Industries, Cambridge, Ontario, Canada), respectively. The total plastic deformation values were 0.015, 0.006, and 0.086 mm, respectively, measured at 0° of unloading.
In-Ovation R had the least deformation due to torquing of the 3 investigated bracket types. Damon Q and Speed on average had approximately 2.5 and 14 times greater maximum plastic deformation, respectively, than did In-Ovation R.
控制根扭矩通常通过在矩形弓丝中引入扭转来实现。本研究的目的是通过分析弓丝的弹性和塑性变形以及在不同扭转角度下的表达扭矩，来研究不同类型的自锁托槽的三阶扭矩。
将正畸托槽安装到一个能够测量各个方向力和力矩的力传感器上。通过一个由定制软件控制的步进电机，将弓丝在托槽中扭转。通过显微镜拍摄头顶图像，并通过光学相关进行处理，以测量变形。
在最大扭转角度为 63°，使用 0.019×0.025 英寸不锈钢丝的情况下， Damon Q（Ormco，橙，加利福尼亚）、In-Ovation R（GAC， Bohemia，NY）和 Speed（Strite Industries，剑桥，安大略省，加拿大）的总弹性和塑性变形值分别为 0.063、0.033 和 0.137 毫米。在卸载 0°时，总塑性变形值分别为 0.015、0.006 和 0.086 毫米。
在研究的 3 种托槽类型中，In-Ovation R 的扭转变形最小。 Damon Q 和 Speed 的最大塑性变形平均分别比 In-Ovation R 大约 2.5 倍和 14 倍。
