LF托槽与传统四翼托槽最大静摩擦力特性的比较

背景：LF托槽是一种新型六翼托槽,相较传统四翼托槽具有多种结扎方式的特点,提示其摩擦力特性可能具备多样性。目的：观察干湿两种条件下LF托槽相对于传统四翼托槽所表现的摩擦力特点。方法：利用扫描电镜观察不锈钢方丝的表面形貌,根据其特征确定方丝拉拔方向,再据此设定在摩擦力试验阶段不锈钢方丝的运行方向。在干湿两种条件下,按照析因设计方案分别测试结扎主翼、结扎全部翼两种结扎方式下的LF托槽、传统四翼托槽与不锈钢方丝以及圆丝组合时的摩擦力大小。结果与结论：与传统四翼托槽相比,LF托槽结扎主翼时最大静摩擦力显著减小,结扎全部六翼时最大静摩擦力显著增加。传统四翼托槽与LF托槽湿润条件下的最大静摩擦力均高于干燥条件下的最大静摩擦力(P  < 0.05)。不锈钢方丝的最大静摩擦力显著大于不锈钢圆丝(P < 0.05)。表明LF托槽具有灵活的摩擦力特性,采用不同结扎方式可提供不同大小的摩擦力。这提示主翼结扎方式下的LF托槽可以用于滑动法关闭间隙阶段,六翼结扎方式下的LF托槽可用于牙齿位置的精确调整。

A comparative study of the static friction force between LF bracket and conventional bracket

BACKGROUND:Compared with traditional brackets, LF brackets have potential of various friction characteristics because of their different ligating methods. But report about it is insufficient.OBJECTIVE:To study the frictional characteristics of LF bracket when it is sliding along an archwire compared with regular four wings bracket in dry and wet state.METHODS:The surface states of the stainless steel rectangular archwires were observed with scanning electronic microscope in order to determine the drawing direction when they were manufactured. In dry and artificial saliva environment, the friction was measured by XF-Ⅰtesting machine according to the drawing direction. All factors and levels were completely combined according to factorial designs, including environment, bracket, archwire. RESULTS AND CONCLUSION:Compared with the regular four wings brackets, the friction of the LF brackets was lower when the main wings were ligated, but higher when all the six wings were ligated. The friction in wet state was higher than that in dry state (P < 0.05). The friction of stainless steel rectangular archwires was higher than that of stainless steel round archwires (P < 0.05). The results above indicate that different ligating methods of LF brackets may provide different frictions. The method of ligating the main wings of LF bracket can be applied in the process of space closure; and the method of ligating all the wings of LF bracket can be applied in moving teeth to a certain position precisely.