四种Beta钛-正畸弓丝合金成分及力学性能的比较研究

目的比较四种Beta-钛正畸弓丝的合金成分及力学性能,为临床选择提供参考。方法选用EDAX X-射线能谱分析仪,联合SUPRATM55热场发射扫描电子显微镜（SEM）分析弓丝的合金元素成分。采用纳米压痕技术测定弓丝纳米弹性模量及硬度;采用三点弯曲试验方法测定弓丝负荷-形变曲线,比较弓丝的力学性能。结果四种Beta-钛丝合金成分中均含有Ti、Zr、Mo、Sn四种元素,Ti在四种Beta-钛丝中所占比重均高于70%。Ormco和Masel公司的Beta-钛丝弹性模量小于Smart与GAC公司的Beta-钛丝。GAC的Beta-钛丝硬度最大。当形变3mm的负荷完全去除时,四种Beta-钛丝均有残余形变,Smart和Ormco大于GAC和Masel公司的Beta-钛丝残余形变。结论四种Beta-钛丝合金成分基本相同,力学性能有一定差异,可根据临床实际情况选取合适弓丝。     

含铜镍钛合金丝口腔温度下三点弯曲性能的研究

目的确定不同含铜镍钛合金丝在口腔温度下(37℃)三点弯曲性能的差异。方法选取CopperNi-Ti 27℃、Copper Ni-Ti 35℃、Copper Ni-Ti 40℃各5根(0.406 mm×0.559mm),在37℃下,利用微力测试仪进行三点弯曲实验,测定其加载平台期和卸载平台期的力值。结果 Copper Ni-Ti 27℃、Copper Ni-Ti 35℃、Copper Ni-Ti40℃在37℃环境下,位移1.5mm时,加载力值分别为3.99±0.09(N)、3.08±0.13(N)、2.60±0.05(N),卸载力值分别为2.81±0.03(N)、1.66±0.10(N)、1.17±0.05(N)。结论含铜镍钛合金丝在口腔环境温度下,在外力的作用下,镍钛合金丝变形诱发马氏体。不同镍钛合金中马氏体含量不同,因此,产生的力值不同,临床上应根据具体情况进行选择。     

直流电热处理对镍钛合金丝三点弯曲性能的影响

目的 探讨直流电热处理后镍钛合金丝三点弯曲性能的变化规律,以期更好地发挥镍钛合金丝在临床治疗中的作用.方法 选择两种超弹性镍钛合金丝(弓丝A:圣马特超弹性镍钛合金牙齿矫形丝;弓丝B:SENTALLOY(R)超弹性镍钛合金丝)和两种热激活镍钛合金丝(弓丝C:圣马特热激活镍钛合金牙齿矫形丝;弓丝D:L&H镍钛丝),用加热仪分别对弓丝进行0(对照)、1.0、1.5、2.0、2.5 s的直流电热处理(恒定电流强度6.36 A);在37℃下利用三点弯曲实验检测弓丝的性能变化.结果 热处理后镍钛合金丝的平台期应力值均有所增加,加热2.0 s后弓丝A、B、C、D中点加载位移1.5 mm时,应力值分别为(4.33±0.07)、(4.52±0.08)、(4.07±0.05)、(3.27±0.15)N,与对照[分别为(3.85±0.11)、(3.28±0.09)、(3.62±0.07)、(2.91±0.23)N]相比,差异有统计学意义(P＜0.05).结论 在正畸治疗的不同阶段可利用直流电热处理的方法改变镍钛合金丝的形状和超弹性,但应注意控制加热的电流强度和时间,随着加热时间的延长,弓丝硬度增加.

Abstract：

Objective To investigate the mechanical properties of Ni-Ti wires with direct electric resistance heat treatment(DERHT) method in three-point bending tests. Methods Two superelastic Ni-Ti wires(wire A: Smart SE, wire B: SENTALLOY SE, 0.406 mm ×0.559 mm) and 2 heat-actived Ni-Ti wires(wire C: Smart SM, wire D: L&H TITAN, 0.406 mm ×0.559 mm) were selected. They were heattreated using the DERHT method by a controlled electric current(6. 36 A) applied for different period of time[0(control), 1.0, 1.5, 2. 0, 2. 5 seconds). Then, a three-point bending test was performed under controlled temperature (37 ℃ ) to examine the relationships between the deflection and the load in the bending of wires. Results After DERHT treatment, the plateau in the force-deflection curve of superelastic Ni-Ti wires and heat-actived Ni-Ti wires were increased. When the wires were heated for 2. 0 seconds and deflected to 1.5 mm, the loading force of A, B, C and D Ni-Ti wires increased from (3.85 ± 0. 11 ),(3.62±0.07), (3.28±0.09), (2.91 ±0.23) Nto (4.33 ±0.07), (4.07 ±0.05), (4.52±0.08),(3.27 ± 0. 15 ) N respectively. Conclusions DERHT method is very convenient for clinical use. It is possible to change the arch form and superelastic force of NiTi wires. The longer the heating time is, the more the superelastic characteristics of the wires are altered.     

Effect of time and pH on physical-chemical properties of orthodontic brackets and wires

Objective:To test the hypothesis that treatment time, debris/biofilm, and oral pH have an influence on the physical-chemical properties of orthodontic brackets and arch wires.Materials and Methods:One hundred twenty metal brackets were evaluated. They were divided into four groups (n  =  30) according to treatment time: group C (control) and groups T12, T24, and T36 (brackets recovered after 12, 24, and 36 months of treatment, respectively). Rectangular stainless-steel arch wires that remained in the oral cavity for 12 to 24 months were also analyzed. Dimensional stability, surface morphology, composition of brackets, resistance to sliding of the bracket-wire set, surface roughness of wires, and oral pH were analyzed. One-way analysis of variance, followed by a Tukey multiple comparisons test, was used for statistical analysis (P < .05).Results:Carbon and oxygen were shown to be elements that increased expressively and in direct proportion to time, and there was a progressive increase in the coefficient of friction and roughness of wires as a function of time of clinical use after 36 months. Oral pH showed a significant difference between group T36 and its control (P  =  .014).Conclusions:The hypothesis was partially accepted: treatment time and biofilm and debris accumulation in bracket slots were shown to have more influence on the degradation process and frictional force of these devices than did oral pH.     

Beta-钛与镍钛、不锈钢正畸弓丝合金成分、表面形貌以及力学性能的对比研究

目的:比较Beta-钛丝与正畸临床常用的超弹性镍钛丝及不锈钢丝的合金成分、表面形貌以及力学性能,为临床应用提供参考。方法:选取Beta-钛丝、超弹性镍钛丝及不锈钢丝,弓丝尺寸均为0.43 mm×0.64 mm。选用EDAX X-射线能谱分析仪联合SUPRATM55热场发射扫描电子显微镜分析弓丝的合金成分,观察其表面形貌。使用Nano Indenter XP纳米压痕测试机测定弓丝弹性模量及硬度,使用Instron 5848微力材料试验机,三点弯曲测定弓丝的负荷-形变曲线。结果:Beta-钛丝合金成分中含有Ti、Zr、Mo、Sn 4种元素,不锈钢丝含有Fe、Mn、Cr、Si,超弹性镍钛丝含有Ni、Ti 2种元素。不锈钢丝表面比Beta-钛丝及镍钛丝光滑。Beta-钛丝的弹性模量及硬度明显小于不锈钢丝,略大于超弹性镍钛丝。当形变3 mm的负荷完全去除时,Beta-钛丝及不锈钢丝均有残余形变,超弹性镍钛丝形变完全恢复。结论:Beta-钛丝、超弹性镍钛丝及不锈钢丝依据其性能适用于正畸治疗的不同阶段。     

不同正畸镍钛矫正弓丝机械性能差异的对比研究

目的 评价口腔正畸临床中常用的各种镍钛矫正弓丝的机械性能差异,指导临床医师进行正确的选择.方法 选取了8种常用的镍钛矫正弓丝,采用模拟口腔温度(37℃)进行三点弯曲试验,检测矫正弓丝变形程度(位移)与弓丝产生的回复力(载荷)之间的关系.结果 0.016英寸镍钛矫正圆丝中,2mm位移卸载时载荷值最小的为3M热激活镍钛丝;而载荷值最大的为Smart SE镍钛丝;滞后值最低为Smart SE;有研I镍钛丝在4mm位移的三点弯曲实验中,并未出现平台期.0.016×0.022英寸镍钛矫正方丝中,平台期载荷值、滞后值、2mm位移卸载值最低的均为L&H Titan 镍钛方丝.结论 三点弯曲试验通过模拟口腔温度的三点弯曲试验显示了加载和卸载的一个过程.本研究采用的有研I镍钛圆丝不具有超弹性,而其余镍钛丝都具有超弹性.四种镍钛矫正圆丝中,3M热激活镍钛丝能提供最柔和的矫治力量(≈50g);而Smart SE镍钛丝提供的矫治力量最大(≈105g)且最稳定.四种镍钛矫正方丝中,L&H Titan镍钛方丝不仅能提供最为柔和的矫治力,也能提供最为稳定的矫治力.     

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.     

不同正畸钢丝的机械性能测试比较及临床意义

目的　比较澳丝、美国正畸钢丝、仿澳丝、国产不锈钢丝、经热处理国产不锈钢丝的刚度、弹性、强度、抗疲劳性能 ,为临床合理选用正畸钢丝提供依据。方法　对上述 5种临床常用正畸钢丝的弹性模量、弹性极限、回弹角、抗拉强度、扭转强度、疲劳强度等机械性能进行测试和比较。结果　得出 5种正畸钢丝的刚度、弹性、强度、抗疲劳性能等比较数据。结论　在临床上应该根据不同矫治时机的需求以及钢丝的不同特性合理选用钢丝。     

两种石英纤维桩机械性能与结构特征的实验研究

目的:对比研究两种石英纤维桩的机械性能和结构特征.方法:选择锥形石英纤维桩D.T.Light post(DT)和表面带固位凹槽的锥形石英纤维桩Macro-Lock post(ML)各15根用作实验研究对象.万能测试机测试其机械性能,扫描电镜观察纤维桩结构,Image J软件分析纤维直径及含量.结果:DT和ML纤维桩的断...     

In vitro investigation into the biological assessment of orthodontic wires

The alloys used in orthodontics are subject in the moist environment of the oral cavity to various corrosion processes. If the products of the corrosion are introduced into a biological system they may cause changes. In the present investigation the corrosion rate of 23 different orthodontic wires (preformed archwires and straight wires) made from 5 different alloys were examined in a nutrient medium by ICP-AES analysis, and the influence of the corrosion products on the cytotoxicity of a fibroblast culture was investigated using Mosmann's MTT test. The nickel-titanium wires Nitinol^®, Sentalloy^® and Original Chinese Wire^® and the -titanium alloy TMA^® had no effect on the rate of cell proliferation. Nor did stainless steel wires inhibit growth significantly, with the exception of Australian Wire^® and Wildcat Wire^®. The manganese-steel alloys Noninium^® h and Mezanium^® caused significant reductions in growth rate, which were attributed to the manganese ions released by the corrosion. The most severe growth inhibition was caused by the Co–Cr–Ni alloy Elgiloy^®, and this reaction is independent of the 4 levels of resilience. The degree of growth inhibition depended upon the concentration of corrosive cobalt and nickel ions in the eluate. In spite of the differences observed, all the orthodontic wires examined are graded under ISO-standard 10993-5 as non-cytotoxic. The degree of toxicity was found to be determined essentially by the corrosion rate of the alloy and the cytotoxic characteristics of the resulting trace elements.     

自锁托槽与传统托槽矫治器对牙周健康影响的比较研究

目的 对比戴用自锁托槽与传统托槽矫治器后牙周指数的变化.材料和方法选取12～18岁正畸患者80例,按矫治器类型分为两组：实验组,40例采用AO公司生产的T3自锁托槽矫正的患者;对照组,采用杭州西湖公司生产的徐氏托槽矫正的患者40例.由同一牙周专科医师分别检测80例患者治疗前和治疗6个月的各项牙周指数（GI,PLI,SBI,PD）.结果 治疗6个月后两组间牙周指数（GI,PLI,SBI,PD）差异无显著性.结论 自锁托槽矫治器不会更有利于牙周组织的健康,牙周的健康状况取决于患者的口腔卫生状况.     

镍钛圆丝弯曲变形后的力学性能分析

目的研究镍钛圆丝弯曲变形后的力学性能，为临床排齐牙列阶段合理地选择弓丝提供参考依据。方法采用能进行双端梁弯曲实验的微型正畸弓丝测试仪，对直径为0．36、0．41、0．46mm的镍钛圆丝在0．56mm×0．71mm的标准方丝弓托槽内进行加载、卸载实验，定量分析载荷形变规律。结果在力矩值为0．03N·m的载荷下，0．36mm与0．41mm的镍钛圆丝均表现出良好的超弹性，而0．46mm的镍钛圆丝则未表现出典型的超弹性；当弓丝产生0．01-0．02N·m最适矫治力矩时，在扣除接触角的基础上．直径为0．36、0．41、0．46mm的镍钛圆丝的弯曲形变范围分别为21．0°-49．5°、7．2°-23．7°、6．5°-9．5°。结论利用镍钛圆丝排齐牙列时，应根据牙齿倾斜或旋转错位的轻重程度，在保证弓丝发生变形后能产生牙移动所需的最适矫治力矩的前提下，尽量选择矫治力较持续、衰减较缓慢的弓丝。     

Friction between different wire bracket combinations in artificial saliva--an in vitro evaluation

Objective

The objective this work was to assess the friction coefficient between brackets and wires of different materials under conditions simulating the oral environment.

Material and Methods

Stainless steel (SS) and titanium-molybdenum alloy (TMA) wires of 0.019x0.025-in diameter (American Orthodontics) and polycarbonate bracket (American Orthodontics), ceramic bracket (American Orthodontics), and metal bracket (3M Unitek) with slots of 0.022x0.030-in were used. The friction coefficient was assessed by means of mechanical traction with the system immersed in artificial saliva. The mean roughness of both wire surface and bracket slots was evaluated by using a surface profilometer.

Results

The system using TMA wire and polycarbonate bracket had the highest roughness (p<0.05). SS wire with ceramic bracket had the highest friction coefficient, whereas the use of metallic bracket yielded the lowest (p<0.05). However, it was observed a statistically significant difference in the system using TMA wire and ceramic bracket compared to that using TMA wire and polycarbonate bracket (p=0.038).

Conclusion

Ceramic brackets in association with SS wire should be judiciously used, since this system showed a high friction coefficient.     

Super-elasticity in vitro assessment of CuNiTi wires according to their Austenite finish temperature and the imposed displacement

ObjectivesTo assess the super-elasticity of CuNiTi wires (Ormco, Glendora, Calif) according to their Austenite finish temperature (Af) and to the imposed displacement. The secondary objective was to compare the wire dimensions with the stated measurements and to study interbatch variability.Materials and Methods10 types of CuNiTi wires (Ormco, Glendora, Calif) (n = 350) were investigated at 36 ± 1°C, with conventional brackets (Victory Series, 3M Unitek, Monrovia, Calif). Tensile test with coronoapical displacement ranging from 1 to 5 mm of the canine bracket was imposed. The wire dimensions were initially measured from two batches (n = 10).ResultsDimensional heterogeneity varied by ± 2.00% compared to the manufacturer''s data, and even up to 5.54% for 0.014-inch CuNiTi (P = .00069). However, all unloading forces were reproducible. In decreasing order, the forces delivered by a CuNiTi 27 were greater than those with CuNiTi 35 and 40. The super-elasticity was expressed only for displacements of 1 to 2 mm, at best up to 3 mm for 0.014-inch CuNiTi 27.ConclusionsThe value of Af as well as the amount of imposed displacement seem to influence the expression of the super-elasticity of CuNiTi wires and the amount of corrected malocclusion. Among the tested wires, under these experimental conditions, 0.014-inch wire could be suitable as a first archwire. CuNiTi 35, therefore, seems to offer the best compromise among the force level, the expression of super-elasticity and the amount of malocclusion correction.     

九种镍钛矫正弓丝相变温度的对比研究

目的 确定临床常用的9种镍钛矫正弓丝的马氏体相、奥氏体相、R相温度以及相变温度范围,为镍钛矫正弓丝的力学性能研究提供依据.方法 采用差热扫描(differential scanning calorimetry,DSC)技术,确定9种临床常用镍钛矫正弓丝(A组:Smart SE圆丝;B组:Kleen PakRTM圆丝;C组:中国镍钛牙弓丝圆丝;D组:Nitinol heat-activated圆丝;E组:Smart SE方丝;F组:Damon CuNiTi方丝;G组:L&H Titan方丝;H组:中国镍钛牙弓丝Ⅰ方丝;Ⅰ组:中国镍钛牙弓丝Ⅱ方丝;每组3根弓丝)的相变过程和相变温度.结果 A、B、D组镍钛矫正弓丝的奥氏体相结束温度(austenite finish,Af)分别为22.4℃、21.9℃、22.5℃,低于25℃,在口腔温度下不能再发生相变,没有形状记忆性能;C、H组镍钛矫正弓丝在DSC仪扫描范围内未发现相变状态.E、G、I组镍钛矫正弓丝在室温下为马氏体相和奥氏体相的混合体,Af分别为34.3℃、36.6℃、38.5℃,与口腔温度接近,具有形状记忆性能.F组镍钛矫正弓丝Af为61.5℃,远高于口腔温度,在口腔环境中也为马氏体相和奥氏体相的混合体,在口腔温度较高的情况下才能完全转变为奥氏体相,具有形状记忆功能.结论 临床常用的9种镍钛矫正弓丝的相变温度和相变过程各不相同,并非所有弓丝均具有形状记忆性能,所以应根据临床治疗目的选用不同的弓丝.