主动和被动自锁-一个神话？
Active and passive self-ligation-a myth?
机构信息
Orthodontic Department, University of Basel, Switzerland.
出版信息
Angle Orthod. 2011 Mar;81(2):312-8. doi: 10.2319/041310-205.1.
OBJECTIVE
To compare the frictional behavior of several self-ligating brackets with that of normal brackets both with and without tipping force-moments and in combination with different archwire dimensions.
MATERIALS AND METHODS
The resistance to sliding (RS) of seven self-ligating brackets, a conventional bracket, and a ceramic bracket with a low-friction clip were evaluated in combination with three different archwires and tipping force-moments of 0 and 10 Nmm. The center of rotation for the measurements was set within the center of the bracket or with a 10-mm offset. Resistance to sliding was measured using an Instron 3344 at a cross-head speed of 10 mm/min at a temperature of 36°C.
RESULTS
Without a tipping moment, RS increased with the active self-ligating brackets with increasing archwire size. No RS was found for any of the passive self-ligating brackets. The 10-Nmm tipping moment resulted in more RS and was similar for all bracket and archwire combinations. RS was approximately doubled when the center of rotation was located at the bracket rather than with a 10-mm offset.
CONCLUSIONS
RS between brackets and archwires is highly dependent on the experimental setup. Different setups can result in contradictory results. Almost 1 N of traction force is lost in RS when a moment of 10 Nmm is placed at a rotational center 10 mm from the bracket.
目的
比较几种自锁托槽与传统托槽和带低摩擦附件的陶瓷托槽在有或无转矩以及结合不同弓丝尺寸时的摩擦行为。
材料和方法
评估了 7 种自锁托槽、一种传统托槽和一种带低摩擦附件的陶瓷托槽与三种不同尺寸的弓丝组合时的滑动阻力（RS），转矩为 0 和 10 Nmm。测量的旋转中心设置在托槽中心或 10mm 偏置处。RS 使用 Instron 3344 在 36°C 温度下以 10mm/min 的十字头速度进行测量。
结果
无转矩时，随着弓丝尺寸的增大，带主动自锁托槽的 RS 增大。任何被动自锁托槽均未发现 RS。10Nmm 的转矩会导致更多的 RS，并且对于所有托槽和弓丝组合均相似。当旋转中心位于托槽而不是 10mm 偏置处时，RS 大约增加了一倍。
结论
托槽与弓丝之间的 RS 高度依赖于实验设置。不同的设置可能会导致相反的结果。当在距托槽 10mm 的旋转中心施加 10Nmm 的转矩时，RS 会损失近 1N 的牵引力。
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