弓丝与结扎方法对摩擦力影响的实验研究

目的:了解4种弓丝和2种结扎方法对托槽与弓丝摩擦力的影响。方法:在干燥条件下,按正交实验设计,使用LJ-500型拉力实验机的微型测力计,测试4种弓丝与6种直丝托槽组合及采用2种结扎法时在后牙段的动、静摩擦力。所得数据进行方差分析和二次响应回归分析。结果:在弓丝与所有托槽组合中,0.018英寸×0.025英寸(1in=2.54cm)的不锈钢方丝动、静摩擦力最小,0.019英寸×0.025英寸的不锈钢方丝动、静摩擦力最大,0.018与0.020英寸不锈钢圆丝介于两者之间,但0.018英寸圆丝的动摩擦力较大,0.020英寸圆丝的静摩擦力较大。动、静摩擦力平均百分比从小到大依次为:0.019英寸×0.025英寸方丝、0.020英寸圆丝、0.018英寸×0.025英寸方丝、0.018英寸的圆丝。弹力橡皮圈结扎的动、静摩擦力及动、静摩擦力平均百分比均大于不锈钢丝结扎。结论:0.018英寸的不锈钢圆丝不适宜滑动机制;在0.022英寸系统的直丝托槽中,用0.019英寸×0.025英寸不锈钢方丝关闭间隙,应尽可能加强支抗控制;干燥条件下弹力橡皮圈结扎不利于托槽、弓丝滑动。     

2种橡皮圈在人工唾液条件下力值衰减的对比研究

目的探讨人工唾液条件下,超滑结扎橡皮圈和常规结扎橡皮圈在不同时间段力值的衰减情况。方法选用同一厂家生产的相同内径、外径、厚度的超滑结扎橡皮圈和常规结扎橡皮圈,利用Instron万能材料力学实验机,测量两种橡皮圈在人工唾液条件下,模拟结扎在MBTTM直丝弓托槽上时,8个时间段（0、1、24h,1、2、3、4、6周）力值的衰减。结果最初1h,超滑结扎橡皮圈力值衰减为22.04%,常规结扎橡皮圈为30.30%,超滑结扎橡皮圈小于常规结扎橡皮圈。两种材料橡皮圈力值衰减的趋势是一致的,最初1h产生了快速的力值衰减,以后逐渐平稳不再有太大的变化。人工唾液条件下不同时间段超滑结扎橡皮圈和常规结扎橡皮圈力值衰减的差异无统计学意义（P=0.077）。结论超滑结扎橡皮圈和常规结扎橡皮圈在人工唾液条件下结扎在MBTTM直丝弓托槽上时,8个时间段的力值衰减形式一致。     

不同结扎方式对舌侧托槽静摩擦力的影响

目的：探讨在不同结扎方式下,舌侧托槽在牙弓后段所产生静摩擦力的差异。方法：测试2种舌侧托槽系统（STb、e·Brace）与4种弓丝（0．016英寸镍钼合金丝、0．016英寸不锈钢圆丝、0．016×0．022英寸镍钼合金丝、、0．016×0．022英寸不锈钢方丝）组合在3种结扎方式下的静摩擦力。结果：不同结扎状态下,舌侧托槽－弓丝间的静摩擦力有显著性差异（P＜0．05）。结论：舌侧托槽－弓丝组合的静摩擦力随结扎力的增大而增大。     

人工唾液中直丝弓托槽与弓丝静摩擦力的实验研究

目的探讨人工唾液条件下,不同时间,几种直丝托槽与弓丝在后牙段的静摩擦力特点。方法在人工唾液条件下,4个时间段,测试4种直丝托槽与4种弓丝组合在后牙段的静摩擦力。结果0.46mm不锈钢圆丝的静摩擦力最小,0.48mm×0.64mm不锈钢方丝的静摩擦力最大。弓丝、托槽组合在人工唾液条件下作用15d静摩擦力最大、30d静摩擦力最小。结论0.46mm不锈钢圆丝的静摩擦力最小;人工唾液作用30d静摩擦力最小。     

单个链状橡皮圈弹力结扎牵引尖牙远移的临床观察

目的　比较单个链状橡皮圈弹力结扎与传统的弹力橡皮圈牵引尖牙远中移动的效果。方法　随机选择16例因正畸需要拔除上颌双侧第一双尖牙患者 ,用方丝弓矫治器排齐牙列换上 0 .0 4 6cm(0 .0 18英寸 )的澳丝后 ,以上颌第一磨牙为支抗 ,在患者上颌牙弓的右侧用单个链状橡皮圈弹力结扎 ,左侧用传统正畸弹力橡皮圈牵引尖牙远中移动。比较两种方法牵引尖牙远中移动的速度和支抗丧失的程度。结果　单个链状橡皮圈弹力结扎与传统的弹力橡皮圈牵引尖牙远中移动的速度无显著性差异 (P >0 .0 5 ) ,第一磨牙前移的距离无显著性差异 (P >0 .0 5 )。结论　单个链状橡皮圈弹力结扎可代替传统的弹力橡皮圈用于牵引尖牙远中移动。     

正畸弹力结扎橡皮圈影响摩擦力的研究进展

矫治力必须克服摩擦力才能实现期望的牙齿移动,结扎方式对正畸摩擦力起着非常重要的作用。目前临床上的结扎方式主要有不锈钢丝结扎及弹力结扎橡皮圈结扎,不同的结扎橡皮圈在托槽-弓丝-结扎橡皮圈系统中的摩擦力状况,是正畸医生所关心的问题。笔者就橡皮圈表面处理、橡皮圈形状、橡皮圈的尺寸大小及橡皮圈结扎方式对摩擦力的影响进行综述。     

湿润状态下托槽与弓丝间动摩擦力的实验研究

目的:探究人工唾液条件下不同时间,几种直丝托槽与弓丝在后牙段的动摩擦力状况.方法:在人工唾液条件下,4个时间段:0、15、30、45 d,使用Instron万能材料力学实验机,模拟弓丝在后牙段滑动,按正交设计测试4种直丝托槽与4种弓丝组合在后牙段的动摩擦力.结果:3M MBT托槽的动摩擦力最小,0.48mm×0.64哪方丝的动摩擦力最大,0.46 mm圆丝的动摩擦力最小.弓丝、托槽组合在人工唾液条件下作用15 d动摩擦力最大、30 d动摩擦力最小.结论:0.46 mm圆丝的动摩擦力最小;人工唾液作用30 d动摩擦力最小;3M MBT托槽比较适合于滑动法关闭问隙.     

结扎橡皮圈、链状橡皮圈与镍钛拉簧应力松弛的研究

目的:研究结扎橡皮圈、链状橡皮圈和镍钛拉簧应力松弛的过程,以及它们在相同负载和不同负载时应力松弛的异同.方法:选取结扎橡皮圈、链状橡皮圈和镍钛拉簧各9个,每种试样又随机分为3组,每组3个,使每组分别负载 100 g、150 g 和 200 g.实验过程中定期测量结扎橡皮圈、链状橡皮圈和镍钛拉簧在不同负载下的应力,并对结果进行统计学分析.结果:结扎橡皮圈和链状橡皮圈在最初的48 h内应力松弛明显,衰减到初始应力的85%左右.第32 d 时衰减到初始应力的80%左右.镍钛拉簧在最初1周时应力衰减较明显,减少至初始应力的90%左右,之后基本稳定.结扎橡皮圈和镍钛拉簧在不同负载时应力松弛率相同.链状橡皮圈负载较小时应力松弛较小.结论:镍钛拉簧的弹性优于结扎橡皮圈(主动结扎)和链状橡皮圈;结扎橡皮圈和链状橡皮圈负载后 48 h 内应力衰减较快;负载较小时,链状橡皮圈应力松弛较小.     

口腔正畸托槽与弓丝之间最大静摩擦力与静摩擦系数的实验研究

目的 设计一种体外装置,研究正畸托槽与弓丝之间的最大静摩擦和静摩擦系数.方法 实验选择了一种方丝托槽与两种直径0.4 mm的正畸钢丝,设计实验装置在干燥和有唾液条件下测量托槽与弓丝之间在不同正压力下的最大静摩擦力和静摩擦系数.结果 研究发现,在干燥条件下,国产弓丝与托槽之间产生的最大静摩擦力和静摩擦系数显著大于3 M弓丝,在有唾液时两者无显著区别.结论 不同条件下,弓丝与托槽之间产生的静摩擦力与静摩擦系数不同.     

Lock-loose托槽与传统托槽摩擦力特性的比较研究

目的 在干燥和人工唾液环境中测量Lock-loose托槽结扎中间翼和结扎全翼时与弓丝之间滑动摩擦力和静摩擦力的大小,并与传统四翼托槽和自锁托槽进行对比。方法 应用原子力显微镜观察不锈钢弓丝与不同托槽摩擦前后的表观形貌。选用Lock-loose托槽、传统四翼托槽和自锁托槽,分别与0.406 4 mm、0.457 2 mm不锈钢圆丝和0.457 2 mm×0.634 9 mm、0.482 6 mm×0.634 9 mm不锈钢方丝组合,其中Lock-loose托槽使用结扎中间翼和结扎全翼两种结扎方式。使用电子万能力学实验机测量干燥和人工唾液两种环境下弓丝在托槽内滑动的动、静摩擦力。结果 不同尺寸弓丝与不同托槽摩擦前后的表面粗糙度无明显差异（P>0.05）;Lock-loose托槽结扎中间翼与4种弓丝组合的动、静摩擦力均接近于0,与传统四翼托槽有明显差异（P<0.05）;与0.457 2 mm×0.634 9 mm不锈钢方丝组合时,Lock-loose托槽结扎全翼可以获得最大动、静摩擦力,与传统四翼托槽和自锁托槽的差异有统计学意义（P<0.05）;人工唾液环境中的摩擦力小于干燥环境中的摩擦力（P<0.05）。结论 Lock-loose托槽可以通过不同的结扎方式调节并获得临床所需的摩擦力,有效解决了低摩擦力与强支抗控制的矛盾问题。     

Evaluation of friction between ceramic brackets and orthodontic wires of four alloys

The purpose of this investigation was to determine the frictional resistance offered by ceramic brackets used in combination with wires of different alloys and sizes during in vitro translatory displacement of brackets. Findings with ceramic brackets were also compared with outcomes of treatment with stainless steel brackets. Stainless steel, cobalt-chromium, beta-titanium, and nickel-titanium wires of different cross-sectional sizes were tested in medium-twin monocrystalline ceramic brackets with both 0.018-inch and 0.022-inch slot sizes. The wires were ligated into the brackets with elastomeric modules. Brackets were moved along the wire by means of an Instron universal testing machine, and frictional force was measured by a compression cell and recorded graphically on an xy recorder. Wire friction in the ceramic brackets increased as wire size increased, and rectangular wires produced greater friction than round wires. Beta-titanium and nickel-titanium wires were associated with higher frictional forces than stainless steel or cobalt-chromium wires. These findings follow the same general trends as those found with stainless steel brackets; however, wires in ceramic brackets generated significantly stronger frictional force than did wires in stainless steel brackets.     

Resistance to sliding with 3 types of elastomeric modules

INTRODUCTION: Super Slick (TP Orthodontics, LaPorte, Ind), a polymeric-coated ligature, has recently been introduced to the orthodontic market. The manufacturer claims it will significantly reduce friction. The purposes of this study were to determine whether Super Slick modules show lower friction than round and rectangular modules and to put the frictional forces into perspective with a self-ligating bracket. METHODS: Maxillary premolar, stainless steel, self-ligating, and monocrystalline brackets with .022-in slots were used with straight lengths of .018-in and .019 x .025-in stainless steel wires. Buccal segment models were set up with 1 molar band and 2 premolar brackets for each test group: self-ligating brackets with the slide closed, self-ligating brackets with the slide open, and monocrystalline brackets. The latter 2 groups were tested with all 3 types of elastomeric module. Each setup was tested both under dry conditions and after soaking in a water bath for 1 hour. RESULTS: The self-ligating brackets demonstrated virtually zero friction with each combination of wire and environmental condition. When the different bracket and elastomeric module combinations were compared, significant differences were observed. In all but 2 combinations, round modules provided the least resistance to sliding and rectangular modules the greatest, with Super Slick modules in between the 2. The self-ligating bracket provided the least resistance to sliding of all the bracket/ligation combinations and almost entirely eliminated friction under the conditions of this experiment. CONCLUSIONS: Super Slick modules demonstrated greater resistance to sliding than conventional round modules, but not rectangular. Self-ligating brackets provided the least resistance to sliding of all bracket/ligation combinations and were the only method that almost entirely eliminated friction. The .018-in and .019 x .025-in wires exhibited similar friction in the dry state, but, when wet, the .018-in wire produced less friction. Ceramic brackets demonstrated greater resistance to sliding than stainless steel brackets. Lubrication reduced the friction with .018-in wires and increased it for .019 x .025-in wires.     

Friction of orthodontic elastomeric ligatures with different dimensions

The aim of this study was to evaluate in vitro the effect of variations in the size of elastomeric ligatures on the static frictional resistance generated by orthodontic sliding mechanics under dry condition. Frictional forces generated by elastomeric ligatures treated with a lubricating material (silicone) were analyzed as well. An Instron testing machine was used to assess the static frictional forces of a 0.019 x 0.025-inch stainless steel rectangular wire that was ligated to a molar convertible tube and to three stainless steel 0.022-inch pre-adjusted brackets with elastomeric ligatures with different dimensions: small, medium, and large. The static friction produced by two prototypes of silicone-lubricated elastomeric ligatures was also measured. The small and medium elastomeric ligatures produced significantly less friction than the large ligatures. No statistically significant difference was found between small and medium ligatures. The decrease in frictional forces of small and medium modules had to be ascribed mainly to the smaller thickness of both ligatures with respect to large ligatures. The lubricated elastomeric ligatures generated significantly smaller frictional forces than nonlubricated elastomeric ligatures with different dimensions. The variation in the dimensions of the elastomeric ligatures is able to influence the static frictional resistance generated by orthodontic sliding mechanics in the buccal segments. The use of small and medium elastomeric ligatures determines a 13-17% decrease in static friction compared with large ligatures. Silicone-lubricated modules can reduce static friction by 23-34% with respect to the small and medium nonlubricated elastomeric ligatures and by 36-43% compared with nonlubricated large ligatures.     

Comparative friction of orthodontic wires under dry and wet conditions

Kinetic coefficients of friction for stainless steel, beta-titanium, nickel-titanium, and cobalt-chromium arch wires were measured on a smooth stainless steel or Teflon surface. A universal materials testing instrument was used to pull 0.017 X 0.025-inch rectangular arch wires through a pneumatically controlled binding surface. Classical friction relationships were evaluated by varying applied normal force--similar to ligature tie force--via this pneumatic control. Coefficients of friction were determined under dry and wet (artificial saliva) conditions. Frictional force values, and thus coefficients of friction, were found to increase with increasing normal force for all materials. Beta-titanium and stainless steel wires sliding against stainless steel, and stainless steel wire on Teflon consistently exhibited the lowest dry friction values. Artificial saliva increased friction for stainless steel, beta-titanium, and nickel-titanium wires sliding against stainless steel. Artificial saliva did not increase friction for cobalt chromium, stainless steel sliding against stainless steel, or stainless steel wire on Teflon compared to the dry condition. Stainless steel and beta-titanium wires sliding against stainless steel and stainless steel wire on Teflon showed the lowest friction values for the wet condition.     

Friction produced by types of elastomeric ligatures in treatment mechanics with the preadjusted appliance

The objective was to compare the frictional forces generated by new nonconventional passive elastomeric ligatures (NCL) and conventional elastomeric ligatures (CL) under dry conditions. An experimental model reproducing the right buccal segment of the upper arch and consisting of five stainless steel 0.022-inch preadjusted brackets (from the second premolar through the central incisor) was used to assess both static and kinetic frictional forces produced by NCL and CL. The frictional forces generated by the 0.019 x 0.025-inch stainless steel wire with the two types of elastomeric ligatures were recorded by sliding the wire into the aligned brackets. The friction produced by the 0.014-inch superelastic nickel titanium wire was evaluated both in the presence of aligned brackets and of three-mm misaligned canine bracket. The amount of both static and kinetic frictions were minimal (<10 g) in the NCL group in the presence of aligned brackets with both types of wires, whereas it ranged from a minimum of 95.6 g for the 0.014-inch superelastic nickel titanium wire to a maximum of 590.7 g for the 0.019 x 0.025-inch stainless steel wire when using CL. The amount of both static and kinetic frictions in the presence of a misaligned canine bracket in the NCL group were less than half of that shown by the CL group. A recently developed passive ligature system is able to produce significantly lower levels of frictional forces in vitro when compared with conventional elastomeric modules.     

A comparison of self-ligating and conventional orthodontic bracket systems.

Abstract

This ex-vivo study compared the static frictional resistance of three self-ligating brackets with a conventional steel-ligated Ultratrimm bracket. The effects of archwire size (0.020, 0.019 x 0.025 and 0.021 x 0.025-inch), bracket/archwire angulation (0, 5 and 10 degrees) and the presence of unstimulated human saliva were investigated. The study demonstrated that both increases in wire size and bracket/archwire angulation resulted in increased static frictional resistance for all bracket types tested, with the presence of saliva having an inconsistent effect. Mobil-Lock Variable-Slot had the least friction for all wires for 0 degree angulation. However, with the introduction of angulation, the values were comparable to those of the other brackets. Activa brackets had the second lowest frictional resistance, although high values were found with 0.019 x 0.025-inch wires. SPEED brackets demonstrated low forces with round wires, although with rectangular wires or in the presence of angulation, friction was greatly increased. Ultratrimm brackets produced large individual variation, confirming the difficulty in standardizing ligation force, although under certain conditions, significantly larger frictional forces were observed. In conclusion, self-ligating brackets showed reduced frictional resistance in comparison to steel ligated brackets only under certain conditions.     

Friction of conventional and self-ligating brackets using a 10 bracket model

The friction generated by various bracket-archwire combinations previously has been studied using in vitro testing models that included only one or three brackets. This study was performed using a specially designed apparatus that included 10 aligned brackets to compare the frictional resistance generated by conventional stainless steel brackets, self-ligating Damon SL II brackets and Time Plus brackets coupled with stainless steel, nickel-titanium and beta-titanium archwires. All brackets had a 0.022-inch slot, and five different sizes of orthodontic wire alloys used. Each bracket-archwire combination was tested 10 times, and each test was performed with a new bracket-wire sample. Time Plus self-ligating brackets generated significantly lower friction than both the Damon SL II self-ligating brackets and Victory brackets. However, the analysis of the various bracket-archwire combinations showed that Damon SL II brackets generated significantly lower friction than the other brackets when tested with round wires and significantly higher friction than Time Plus when tested with rectangular archwires. Beta-titanium archwires generated higher frictional resistances than the other archwires. All brackets showed higher frictional forces as the wire size increased. These findings suggest that the use of an in vitro testing model that includes 10 brackets can give additional interesting information about the frictional force of the various bracket-archwires combinations to the clinician and the research worker.