国产陶瓷托槽与金属弓丝间滑动摩擦力的研究

目的检测体外条件下国产多晶体氧化铝陶瓷托槽与金属弓丝在不同夹角时的滑动摩擦力,为其改良提供参考信息。方法利用摩擦力测量装置检测弓丝与槽沟的夹角分别为0°和5°时,国产陶瓷托槽分别与0.016、0.016×0.022、0.019×0.025英寸不锈钢丝和镍钛丝间的滑动摩擦力,每组样本量为10。对照组为临床常用多晶体氧化铝陶瓷托槽(Crystaline IV)。结果国产陶瓷托槽的摩擦力显著高于Crystaline IV,且除0°夹角、0.016英寸不锈钢圆丝和镍钛圆丝及0.016×0.022英寸不锈钢方丝外,其余情况下两种陶瓷托槽间摩擦力的差异有显著性(P0.01)。镍钛丝产生的摩擦力高于不锈钢丝,弓丝尺寸增加,摩擦力增加,弓丝与槽沟夹角为5°产生的摩擦力高于0°。结论国产陶瓷托槽的摩擦力性能不能满足临床使用的要求,需要进一步改良。     

牵引力大小对关闭间隙时滑动阻力影响的三维非线性有限元研究

目的探讨滑动法关闭间隙时牵引力大小对弓丝滑动的影响。方法在全牙列及其牙周组织、弓丝、矫治器的三维有限元模型上,用非线性方法计算不同大小牵引力作用下沿0．048cm×0．064cm（0．019英寸×0．025英寸）不锈钢弓丝滑动时,弓丝与托槽的接触点数目、接触力大小等影响滑动摩擦力大小的因素。结果牵引力小于或大于150g时,后牙接触点多、接触正压力大,滑动阻力较大,使滑动受限;150g牵引力时,整段弓丝特别是后段弓丝与托槽接触点均匀,后段弓丝接触正压力最小,滑动阻力最小。结论使用0．048cm×0．064cm（0．019英寸×0．025英寸）不锈钢弓丝滑动关闭间隙时,过小、过大的牵引力均不利于弓丝的滑动,150g力时滑动阻力最小,有利于弓丝的滑动。     

双槽沟矫治技术力学性能的初步实验分析

目的 :设计研制双槽沟固定矫正装置 ,并应用架模拟进行力学性能测试 ,分析考察该矫治系统对正畸牙移动的调控能力。方法 :①设计并整体铸造双槽沟托槽及带环。托槽设置龈端与切端双排槽沟 ,规格为 0 .0 2 2× 0 .0 2 8英寸 ,相距O .0 8mm。带环配置相应的双排颊管 ;②用经典架模拟方法进行牙齿反扭转、竖直、整体远中牵引、上前牙控根性内收等正畸牙移动形式 ,与常规标准方丝弓矫治方法相比较 ,定量评价双槽沟矫治技术的牙齿移动及调控效率 ;③应用经典力学原理 ,结合架模拟数据 ,分析双槽沟矫治装置提高正畸牙移动及调控效率的机制。结果 :(1)成功设计出双槽沟矫正装置的三维模拟图形并制造出实际产品。 (2 )在架模拟状况下 ,双槽沟矫正装置对尖牙的反扭转及竖直运动速率均显著高于对照组 (P 相似文献   

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目的对自锁托槽与传统托槽滑动阻力的大小及变化规律进行对比研究。方法本研究于2011年9—12月在山西医科大学口腔医院和太原理工大学应用力学与生物医学研究所共同完成。根据人体实际弹性模量比例制作含牙周膜的上颌仿真模型,测试自锁托槽和传统托槽分别与0．016英寸、0．018英寸的镍钛丝和0．017英寸×0．022英寸、0．018英寸×0．025英寸、0．019英寸x0．025英寸的不锈钢方丝匹配时的滑动阻力大小。结果使用同种弓丝时,滑动阻力由小到大排列：DamonQ被动自锁托槽〈Tomy主动自锁托槽〈传统金属托槽,两两比较差异有统计学意义（P〈0．05）。同一种托槽情况下,除0．019英寸×0．025英寸不锈钢方丝外,其余滑动阻力都随弓丝直径的增大而增大,且两两比较差异有统计学意义（P〈0．05）。结论临床实践中托槽类型与弓丝的匹配对滑动阻力的影响十分重要,从而实现牙齿的快速有效移动。     

脱落托槽热处理后对摩擦力影响的实验研究

目的测试热处理对托槽与弓丝间最大静摩擦力的影响。方法在干燥条件下,选取0.022×0.028英寸上颌尖牙不锈钢直丝托槽36枚,弓丝为0.019×0.025英寸不锈钢方丝。将36枚托槽随机分成三组,每组12枚,第一组不做任何处理,第二组、第三组托槽背板粘一薄层京津釉质粘结剂,热处理后用探针去除粘结剂,第三组托槽再进行超声清洗5分钟,分别测试这三组托槽与弓丝间最大静摩擦力。结果测得未经处理的上颌尖牙托槽与0.019×0.025英寸弓丝间最大静摩擦力值为74.67±12.73g;热处理及热处理后经超声清洗的托槽与弓丝间最大静摩擦力值分别是66.31±12.44g、61.97±13.47g。结论热处理及热处理后经超声清洗的托槽与弓丝间产生的最大静摩擦力值较未经任何处理的托槽与弓丝间产生的最大静摩擦力值明显减小。     

自锁托槽直丝弓矫治器的初步应用

自锁托槽以自身所附有的槽沟盖将弓丝固定在槽沟内，改变了传统的结扎丝固位方式，明显地减小了矫治器系统的摩擦力，使牙齿在弱力作用下有效移动。自锁托槽直丝弓矫治器对拔牙矫治、需要较强磨牙支抗、以滑动法关闭间隙的病例有特殊意义。     

自锁托槽对关闭拔牙间隙阶段滑动阻力的影响

目的 比较在牙齿关闭拔牙间隙过程中不同自锁托槽和传统托槽与不锈钢丝组合所产生的滑动阻力。方法 在干燥环境下,分别选择2种自锁托槽(被动Damon^®和主动Tomy^®)和传统托槽的2种结扎方式(橡皮结扎圈和结扎丝)与0.019×0.025英寸不锈钢丝组合,测量严重牙列拥挤患者在拔牙后排齐整平的下颌模型上关闭拔牙间隙阶段的滑动阻力。采用方差分析的方法对各项测量数据进行统计学处理。结果 在关闭拔牙间隙阶段,不同托槽组合、组间的滑动阻力的差异均具有显著的统计学意义(P<0.01),最大静摩擦力和滑动摩擦力由小到大依次为被动Damon组<主动Tomy组<结扎丝结扎组<结扎圈结扎组。结论 在关闭拔牙间隙阶段,被动自锁托槽的滑动阻力明显小于主动自锁托槽的滑动阻力,自锁托槽的滑动阻力明显小于传统托槽的滑动阻力。     

不等力值远中移动尖牙的比较研究

目的 研究100 g力与150 g力远中移动尖牙后牙齿移动距离、根尖及根周硬组织的变化.方法 用OPAK直丝弓矫治技术对25名青少年患者在.18×.025的方丝上,应用Ni-Ti螺旋弹簧分别以初始100 g及150 g力牵引尖牙向远中,四周后分别用游标卡尺及Digora分析法比较牙齿移动距离、牙根长度及牙槽骨高度及密度的变化.结果 应用100 g力及150 g力移动尖牙向远中一月,两者的尖牙移动距离有显著性差异(p＜0.01),150 g力侧移动距离大于100 g力侧.而牙根长度、牙槽骨高度及密度无显著性差异(p＞0.05).结论 临床上OPAK矫治器在0.018×0.025英寸不锈钢方丝上应用150 g力移动尖牙向远中是行之有效而且是安全的.     

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。     

自锁托槽矫治器的摩擦力研究进展

随着直丝弓矫治器的问世,滑动机制越来越多的应用于正畸治疗中,而滑动摩擦力在正畸治疗移动牙齿过程中是不可避免的,有研究显示,在滑动机制中摩擦阻力可导致矫治力丧失12%～60%不等。自锁托槽矫治器利用自身特殊结构来关闭槽沟而无需结扎的一类托槽,正在受到越来越多正畸医生的关注。而有关自锁托槽矫治器的摩擦力也随之在近些年来成为正畸学领域的研究热点,本文就自锁托槽矫治器摩擦力的研究进展作一综述。     

Frictional changes in force values caused by saliva substitution

The objective of this study was to determine the magnitude of frictional force changes between several sizes of stainless steel orthodontic wires (0.018 inch round, 0.020 inch round, and 0.018 X 0.025 inch rectangular) and an edgewise bracket (0.022 X 0.028 inch slot) when an artificial saliva medium was introduced. The wires were secured in the bracket slots with a 0.010 inch polyurethane ligatures. The force values in the saliva substitute medium were compared with those produced in a dry control and in glycerin. Clinically significant differences among the environmental conditions and among the wire sizes were found. The introduction of saliva substitute provides a significant reduction in force values.     

The effects of a newly designed twin-slot bracket on severely malpositioned teeth--a typodont experimental study

The aims of this study were to design a twin-slot bracket featuring two horizontal slots and to examine its efficiency in tooth displacement. Based on the structure of a traditional edgewise bracket, an additional slot was added to a twin-slot bracket and the prototype products were fabricated for the typodont experiments. The orthodontic correction of malpositioned canines was conducted on a typodont to examine the efficiency of the twin-slot bracket in tooth displacement compared with a single-slot edgewise bracket. Three modalities of tooth movement requiring a heavy force moment, namely, axial rotation, mesiodistal tipping, and bodily translation, were conducted. The canine positions before and after simulation were measured and the changes identified. Statistical analysis was undertaken using a t-test to determine the significance of the differences in canine repositioning between the two bracket types. The results showed that in the twin-slot bracket group, the treatment changes in the canine position by derotation and uprighting were 40 +/- 3 and 25 +/- 2 degrees, respectively, compared with 20 +/- 5 and 10 +/- 2 degrees in the edgewise group (P < 0.01). When retracted into an extraction space with an initial 10 degrees of mesial tip, the mesiodistal angulation of the canines in the twin-slot bracket group remained unchanged while in the edgewise group the canines became distally tipped by 5 +/- 2 degrees (P < 0.01). The twin-slot bracket significantly increased the bracket width without reducing the interbracket span and therefore can generate increased force moments within the bracket, leading to an improved manipulation in tooth repositioning.     

Intrabracket space and interbracket distance: critical factors in clinical orthodontics

The engineers who designed the Houston Astrodome, Walter Moore and Associates, were engaged to study the effect that different edgewise appliances have on the function of orthodontic beams or wires. They were supplied with tooth width, bracket width, wire size, slot size information, and stainless steel wire specifications. With these data their computer was programmed to model each appliance as a simple beam reflecting its different support conditions. In the study the 0.018, 0.022, and 0.016-inch traditionally slotted appliances were tested in single and twin brackets. In addition the 0.016-inch bimetric appliance (0.016 inch on anterior teeth, 0.022 inch on posterior teeth) was tested. The following wires were used for testing: 0.016 x 0.022 inch, 0.017 x 0.022 inch, 0.018 x 0.025 inch (0.018 inch); 0.018 x 0.025 inch, 0.019 x 0.025 inch, 0.022 x 0.028 inch (0.022 inch); 0.014 x 0.018 inch, 0.015 x 0.019 inch, 0.016 x 0.022 inch (0.016 inch and bimetric). The results as stated in the conclusion statement by Rick Horn, PhD, of Walter Moore and Associates, are (1) for a given appliance and wire size, the amount of deflection allowable at permanent set decreases with decreasing size of teeth; (2) for a given appliance and wire size, the force imparted to the teeth at permanent set increases with decreasing size of teeth; (3) for a given appliance, the amount of deflection at permanent set decreases with increasing wire size; (4) for a given appliance, the force imparted to the teeth at permanent set increases with increasing wire size; (5) the amount of deflection allowable at permanent set is larger for single brackets than double brackets and larger for bimetric brackets than single brackets; (6) the force imparted to the teeth at permanent set is smaller for single brackets than double brackets and smaller for bimetric brackets than single brackets; and (7) of the six types of appliances examined, the bimetric appliance is the most flexible, allowing the most deflection at permanent set with the smallest force imparted to the teeth. This study supports the following thesis: the only way to take advantage of smaller wires and thereby have an appliance deliver maximum resiliency with lighter forces and not loose control is through differential slot sizing.     

Asymmetric space closure

In a vertically slotted 0.022 X 0.028 inch edgewise system, the use of a two-dimensional ribbon arch--0.022 X 0.016 inch from lateral incisor to lateral incisor and 0.016 X 0.022 inch from the canine to the molars--plus an uprighting spring on the canine maintained incisor position while unilaterally protracting a molar-premolar unit by means of sliding mechanics. Five degrees of labial crown torque was placed in the incisor portion of the wire and the uprighting spring exerted a force of 200 to 250 g. The intra-arch force applied to protract the molar--premolar unit was 300 to 350 g.     

A comparative study of frictional forces between orthodontic brackets and arch wires

An in vitro study of simulated canine retraction was undertaken to evaluate the difference in frictional resistance between stainless steel arch wires and steel and ceramic brackets with elastomeric, steel, and self-ligation. Each bracket slot was 0.018 x 0.025 inch. The arch wires used were 0.014-inch, 0.016-inch, 0.018-inch, 0.016 x 0.016-inch, and 0.016 x 0.22-inch stainless steel. A testing apparatus was designed to attempt to simulate the clinical situation in which teeth tip slightly while they slide along the arch wire. Under these testing conditions, the self-ligating steel bracket did not demonstrate less friction than the elastic or steel-ligated stainless steel brackets. For most wire sizes, elastomer-ligated ceramic brackets demonstrated the greatest friction when compared with other bracket/ligation technique combinations. The clinical significance of this study becomes apparent when stainless steel brackets are used on the posterior teeth and ceramic brackets are used on the anterior teeth. If sliding mechanics are used, the anterior teeth may be more resistant to movement than the posterior teeth because of the greater friction of the ceramic brackets. This could result in more posterior anchorage loss than would be expected if only one type of bracket were used.     

Frictional forces between bracket and arch wire

Guiding a tooth along an arch wire results in a counteracting frictional force. Clinically, a mesiodistally applied force must exceed the frictional force to produce a tooth movement. A friction-testing assembly simulating three-dimensional tooth rotations was constructed to study factors affecting friction magnitude. Five wire alloys (standard stainless steel, Hi-T stainless steel, Elgiloy blue, nitinol, and TMA) in five wire sizes (0.016, 0.016 x 0.022, 0.017 x 0.025, 0.018, and 0.018 x 0.025 inch) were examined with respect to three bracket widths (2.2, 3.3, and 4.2 mm) at four levels of retarding force (0, 1, 2, and 3 N). The following factors affected friction in decreasing order: retarding force (biologic resistance), surface roughness of wire, wire size (vertical dimension), bracket width, and elastic properties of wire. The study recommends the application of 0.016 x 0.022 inch stainless steel wire combined with a medium (3.3 mm) or wide (4.2 mm) bracket for an arch-guided mechanism with an 0.018 inch slot. The effective force of this arrangement has to increase twofold to overcome the friction. For TMA wire, however, the effective force must increase sixfold, resulting in a hazardous overload of the anchorage units.     

国产直丝陶瓷托槽摩擦力性能的研究

目的研究国产直丝陶瓷托槽的摩擦力性能。方法利用MTS Tytron250微力试验机测定我院与清华大学联合研制开发的下颌尖牙位直丝陶瓷托槽与0．016英寸不锈钢圆丝、0．016×0．022英寸不锈钢方丝、0．016英寸镍钛丝在不锈钢丝结扎方式下的摩擦力,并以一种进口陶瓷托槽作为对照组。结果国产直丝陶瓷托槽的最大静摩擦力与对照组陶瓷托槽相比差异无显著统计学意义,平均动摩擦力比对照组陶瓷托槽显著降低。结论国产直丝陶瓷托槽的摩擦性能可以满足临床需要。     

Frictional forces when rectangular guiding arches with varying edge bevel are employed

In orthodontic treatment employing arch guided tooth movement, rectangular wires are usually used to achieve three-dimensional controlled tooth movement. In the intention to optimize sliding mechanics and to improve the comfort of patients, edge beveled rectangular orthodontic wires are offered by different manufacturers. The objective of the study presented was to investigate the influence of differing but defined wire roundings on sliding mechanics of canine retraction. Employing the 0.018″ slot system, 0.016″×0.022″ standard steel wires (Remaloy and Remanium, Dentaurum Comp.) were tested. Force loss due to friction during canine retraction was determined using the Orthodontic Measurement and Simulation System (OMSS). In the arch guided distalization of canines, the average loss of force caused by friction was determined to be approximately 50%. Comparing wires with different edge bevel, the rounded wire in contrast to the wire with sharpest edge configuration results in a reduction of friction. Even a moderate wire rounding of the 0.016″×0.022″ steel wire results in about 10% reduction in frictional losses. However, dynamic analysis of tooth movement with the OMSS shows that there is no further improvement of sliding mechanics using wires with edge bevel exceeding the standard rounding of rectangular wires. In contrast, a strong edge bevel may result in a considerable loss of leveling.     

外展曲与支抗磨牙所受舌向力的关系

目的　观察拉尖牙向远中移动时 ,在不同规格的弓丝作用下 ,牵引力对支抗磨牙所产生的舌向分力的大小以及在不同磨牙外展曲宽度下该牵引力舌向分力的大小。方法　利用与北京大学力学系合作研制的力测量仪在Typodont专用蜡上测量使用不同规格、不同刚度的弓丝 [0 4 0mm、0 4 5mm的不锈钢圆丝 ,0 4 0mm、0 4 5mm的澳丝以及 0 4 1mm× 0 5 6mm (0 0 16英寸× 0 0 2 2英寸 )、0 4 6mm× 0 6 3mm(0 0 17英寸× 0 0 2 5英寸 )的不锈钢方丝 ],分别在不同的磨牙外展曲宽度 (1mm、2mm、3mm)下 ,支抗磨牙受到的 15 0 g沿磨牙颊面管牵引钩至尖牙托槽远中翼中点方向的拉尖牙向远中移动力所产生的舌向分力。结果　 (1) 15 0 g拉尖牙向远中移动力会使支抗磨牙受到舌向分力。 (2 )支抗磨牙受到的牵引力的舌向分力随弓丝粗度和刚度的增加而减少 ,弓丝抵抗磨牙所受到的舌侧力作用与弓丝的刚度、粗度成正比。 (3)支抗磨牙受到的牵引力的舌向分力随磨牙外展曲宽度的增加而减少且二者间呈线性关系。结论　拉尖牙向远中移动时支抗磨牙受到舌向分力 ,为避免磨牙向舌侧移动 ,应选择较大刚度且较粗的弓丝或适当加大磨牙外展曲。     

方丝弓矫治技术中应用尖牙向后结扎的临床探讨

目的评价尖牙向后结扎应用于方丝弓矫治技术的临床疗效,并探讨其机制和使用方法。方法临床选择20名拔除第一双尖牙的病人,在方丝弓矫治的牙列排齐整平阶段,应用尖牙向后结扎,在镍钛圆丝的引导下,远中移动尖牙,研究尖牙与第二双尖牙靠拢的速度,并在尖牙移动前后拍摄X线牙片协助评价疗效。结果 尖牙与第二双尖牙靠拢的速度为0.80-1.05mm/月,平均速度0.90mm/月,且不同直径Ni-Ti圆丝引导下速度之间具有显著性差异(P<0.01)。结论尖牙向后结扎应用于方丝弓矫治技术的牙列排齐整平阶段,疗效明显,并缩短方丝弓矫治的疗程。