摘要：
BACKGROUND: Clinical ligation of traditional brackets by stainless steel ligature wires has greater randomness among doctors, and previous studies have mainly concerned on brackets and wires. There are less studies on the differential frictional force due to tight or loose ligation, and moreover, how to define tight ligation or loose ligation is rarely reported. OBJECTIVE: To compare the frictional force of different archwires in multiple brackets with various ligations. METHODS: A plaster model with moderate crowded malocclusion was randomly selected, and copied by 3D digital scanning technologies and Objet30 OrthoDesk3D printing technologies. Then, the models were bonded with Damon Clear brackets, Damon 3MX brackets, 3M traditional MBT brackets and Habit monocrystal brackets. Frictional forces of different brackets on models combined with two types of low frictional NiTi archwires which were 0.30 mm (0.012 inch) and 0.36 mm (0.014 inch) were measured by microcomputer servo dynamometer. Traditional brackets were ligatured by tight ligation and loose ligation, respectively. RESULTS AND CONCLUSION: (1) When low-friction NiTi archwires of 0.30 mm were used, significant differences in the frictional force were found between different brackets with various ligations except for Damon Clear bracket versus 3M bracket with loose ligation as well as Damon Clear bracket versus Damon 3MX bracket (P ＜ 0.05). (2) When low-friction NiTi archwires of 0.36 mm were used, similarity in the frictional force was found between 3M bracket with loose ligation, Damon Clear bracket and Damon 3MX bracket, while there were no significant differences between 3M bracket with loose ligation and Damon 3MX, between 3M bracket with tight ligation and Habit bracket with loose ligation, as well as between Damon Clear bracket and 3M bracket with loose ligation (P ＞ 0.05). Comparing two kinds of archwires, the friction force showed no statistical difference between Damon Clear bracket and 3M bracket with loose and tight ligation (P ＞ 0.05), but a statistical difference was found between Damon 3MX bracket and Habit bracket (P ＜ 0.001), whatever two conventional brackets with tight ligation or loose ligation. To conclude, conventional MBT bracket with loose ligation can reduce frictional force as similar as self-ligating bracket in the alignment phase, and the reduction in the friction force is impacted by archwire size and bracket material.%背景:临床上使用固定矫正器时,不锈钢结扎丝结扎松紧有较大的随意性,以往研究多着重于托槽、弓丝及其他方面,对不锈钢结扎丝结扎松紧在摩擦力中所引起的差异关注较少,也极少对不锈钢结扎丝结扎的松紧度做出有效界定.目的:将不同NiTi弓丝以不同的方式入槽,比较弓丝-托槽间摩擦力的大小.方法:随机选择1例中度拥挤病例石膏模型,通过3Shape三维数字化扫描技术及Objet30 OrthoDesk3D打印技术制作出完全相同的牙列模型,将Damon Clear陶瓷自锁托槽、Damon 3MX金属自锁托槽、3M传统MBT直丝弓金属托槽和Habit传统四翼单晶体陶瓷托槽分别粘接在3D打印模型上,每种托槽分别配以0.30 mm (0.012英寸)低摩擦NiTi弓丝和0.36 mm(0.014英寸)低摩擦NiTi弓丝,其中3M传统托槽、Habit托槽分别配合弓丝紧结扎和松结扎,使用微机伺服测力仪检测弓丝-托槽间的摩擦力.结果与结论:①使用0.30 mm低摩擦NiTi丝时,除Damon Clear组与3M-松结扎组、Damon Clear 组与Damon 3MX组摩擦力无差异外,其余不同材料托槽或不同结扎方式中的摩擦力两两比较差异有显著性意义(P ＜0.05);②当使用0.36 mm低摩擦NiTi丝时,3M-松结扎组与Damon 3MX组、3M-紧结扎组与Habit-松结扎组、Damon Clear组与3M-松结扎组的摩擦力比较无差异(P ＞ 0.05),3M-松结扎组、Damon Clear组及Damon 3MX组的摩擦力相似;③在Damon Clear托槽、3M传统金属托槽紧结扎和松结扎中,两种弓丝间的摩擦力比较无明显差异(P ＞ 0.05);在Damon 3MX金属自锁托槽、Habit传统单晶体托槽紧结扎和松结扎中,两种弓丝间的摩擦力比较差异有显著性意义(P ＜ 0.001);④结果表明在牙矫形初期排挤阶段,MBT金属托槽松结扎技术可降低弓丝-托槽间的摩擦力,甚至达到自锁托槽水平,降低幅度与弓丝尺寸和托槽材料有关.
