Thorstenson Glenys A, Kusy Robert P
Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, USA.
Am J Orthod Dentofacial Orthop. 2002 May;121(5):472-82. doi: 10.1067/mod.2002.121562.
Resistance to sliding was investigated for 3 self-ligating brackets having passive slides and 3 self-ligating brackets having active clips. Four of these products are currently marketed, and 2 are of historic interest. For all cases, an 0.018 x 0.025-in stainless steel archwire was drawn through each bracket at a rate of 10 mm/min over a distance of 2.5 mm. For each bracket, the resistances to sliding were measured at 14 second-order angulations, which ranged from -9 degrees to +9 degrees. Both the dry and the wet (human saliva) states were evaluated at 34 degrees C. From dimensional measurements, the critical contact angles for binding were determined for all products and ranged from 3 degrees to 5 degrees. Below each characteristic critical angle, brackets with passive slides exhibited negligible friction; brackets with active clips exhibited frictional forces as great as 50 cN (50 g). Above each critical angle, all brackets had elastic binding forces that increased at similar rates as angulation increased and were independent of bracket design. Generally speaking, at second-order angulations that exceeded the critical angle, brackets with active clips that had a low critical angle had more resistance to sliding than did brackets with active clips that had a higher critical angle. Brackets with passive slides that had a high critical angle exhibited the lowest resistance to sliding, but could do so at a cost of some loss of control. Nonetheless, self-ligating brackets represent a compromise between friction and control; ie, self-ligating brackets produce frictional forces that are more reproducible than do conventionally ligated stainless steel brackets but without the potential control problems associated with Begg-style brackets.
对3种带有被动滑动装置的自锁托槽和3种带有主动夹的自锁托槽的滑动阻力进行了研究。这些产品中有4种目前正在市场上销售，2种具有历史研究价值。对于所有情况，将一根0.018×0.025英寸的不锈钢弓丝以10毫米/分钟的速度穿过每个托槽，移动距离为2.5毫米。对于每个托槽，在14种二级角度下测量滑动阻力，角度范围为-9度至+9度。在34摄氏度下评估了干燥和湿润（人唾液）状态。通过尺寸测量，确定了所有产品的结合临界接触角，范围为3度至5度。在每个特征临界角以下，带有被动滑动装置的托槽摩擦力可忽略不计；带有主动夹的托槽摩擦力高达50厘牛（50克）。在每个临界角以上，所有托槽都有弹性结合力，随着角度增加，其增加速率相似，且与托槽设计无关。一般来说，在超过临界角的二级角度下，临界角低的带有主动夹的托槽比临界角高的带有主动夹的托槽滑动阻力更大。临界角高的带有被动滑动装置的托槽滑动阻力最低，但可能会牺牲一些控制能力。尽管如此，自锁托槽代表了摩擦力和控制力之间的一种折衷；即，自锁托槽产生的摩擦力比传统结扎的不锈钢托槽更具可重复性，但没有与Begg式托槽相关的潜在控制问题。
