温控型镍钛弓丝力学性能的时效变化

目的:比较不同品牌温控型镍钛弓丝力学性能的长期变化。方法:利用Instron万能材料力学实验机在37℃人工唾液中对4种品牌温控型镍钛圆丝(直径0.016英寸)在3个时间点(0、4、8周)进行改良部分牙弓弯曲实验,绘制加载、卸载的载荷-挠曲曲线,计算各时间点卸载1.5mm的载荷值、卸载2.5～0.5mm之间的刚度平均值和标准差。采用SPSS11.5软件包对数据进行统计学分析。结果:A、B、D 3种温控型镍钛圆丝0周与4周载荷-挠曲曲线很相近,而在8周时加载曲线明显增高,但卸载曲线无显著变化,C弓丝在3个时间点的载荷-挠曲曲线之间均有显著差异。A、B、D 3种弓丝在所有时间点卸载1.5mm载荷值的波动很小,C弓丝8周时卸载力值有所增大。B与D弓丝不同时间点的卸载刚度波动较小,而A与C弓丝卸载刚度随着时间延长有减小趋势。结论:温控型镍钛弓丝随着加载时间的延长,其力学性能有所变化,但其超弹性及形状记忆性能并未改变。     

模拟口腔环境下温控型镍钛弓丝弯曲性能实验

目的:研究4种温控型镍钛弓丝的机械性能差异。方法:在Instron万能材料力学实验机上进行部分改良牙弓弯曲实验,检测4种温控型镍钛弓丝在37℃人工唾液中的载荷位移关系,绘制加载、卸载载荷-位移曲线,并计算卸载刚度及能量损耗值。结果:4种温控型镍钛弓丝在卸载过程中均未出现残余位移,均表现出明显的平台期;其中TP弓丝的卸载力值最大且能量损耗最小,RTF弓丝和OT弓丝卸载曲线接近,卸载时释放力值较小,OT弓丝卸载刚度最小。结论:4种温控型镍钛弓丝均表现出临床所需的超弹性和形状记忆功能,其中TP弓丝释放矫治力大而持久,OT弓丝释放矫治力较为柔和、稳定。     

镍钛正畸弓丝在口腔环境中的腐蚀性变化

口腔环境是一个pH值变化的复杂环境。口腔环境内多种成分能使正畸镍钛弓丝受腐蚀,使其机械性能和生物相容性发生变化。弓丝成分和表面氧化膜的改良可以提高其抗腐蚀抵抗性。本文就口腔环境内镍钛弓丝的腐蚀、抗腐蚀性及其机制作一综述。     

室温型中国镍钛牙弓丝的临床应用

室温型中国镍钛牙弓丝的临床应用周永德黎闻孙振宇杨天淳秦葵庆高柠镍钛合金是６０年代初由美国Ｂｕｅｈｌｅｒ［１］首先发现。中国镍钛丝以其优良的超弹性应用于正畸临床已有十多年的历史，但存在成形性差，不易弯制成形，质脆易折断等缺点。为此，１９９５年秦葵庆等［...     

自制美学镍钛涂层弓丝的耐腐蚀性研究

目的：研究美学镍钛涂层弓丝的耐腐蚀性能。方法：将美学涂层镍钛弓丝与未涂层镍钛弓丝浸泡于人工唾液中,37℃恒温,采用恒电位法测定阳极极化曲线,浸泡实验测定析出镍、铬离子浓度。结果：涂层弓丝的腐蚀电流显著降低,涂层弓丝析出相对低水平的金属离子。结论：美学涂层可降低弓丝合金的腐蚀倾向,提高其耐腐蚀性能。     

正畸弓丝在口腔环境中力学性能的实验研究

作者通过模拟牙矫治实验，测定常用的正畸弓丝在口腔环境中２８天的力学性能变化，结果显示；在口腔环境中，各种弓丝都有力值的下降和残余变形量的增加。力值衰减主要由多动引起，残余变形主要发生在７天内，不锈钢丝力衰减快，镍钛丝性能稳定。带垂曲的弓丝和镍钛丝性能相似，能提供较持续的矫治力。     

氟对镍钛弓丝色泽的影响

目的研究氟对镍钛弓丝色泽的影响。方法将4种镍钛弓丝（IMD、SL、TP、YY）各40个样本,分为4个小组。其中1个为对照组,放入人工唾液中不作处理;3个为实验组,分别放入含有不同浓度氟离子（0.05%、0.10%、0.15%）的氟化人工唾液中进行处理,每天处理3次（早、中、晚）,每次3 min,然后去离子水冲洗样本,去除残留的氟化物溶液后放回人工唾液试管中。28 d后取出样本,观察表面色泽变化和微观形态。结果随着氟离子浓度的增加,弓丝色泽的改变呈持续加重的趋势（P<0.05）。氟离子浓度相同的条件下,IMD与YY色泽改变的差异无统计学意义,SL与TP的差异也无统计学意义（P>0.05）,但IMD和YY的色泽改变均明显高于SL和TP（P<0.01）。结论镍钛弓丝的表面色泽变化随着氟离子浓度的上升而加重。不同品牌的镍钛弓丝在同一氟环境下色泽改变的情况不完全相同。     

4种镍钛正畸弓丝钛离子析出量的体外实验研究

目的:通过测试在人工唾液中4种品牌镍钛正畸弓丝钛离子的析出量,以了解其耐腐蚀性。方法:选择临床常用的4种品牌的镍钛正畸弓丝,分别为3M、SL、TP、SMT,调配人工唾液,并将人工唾液的pH值分别调节为4.0及6.75,减取的正畸弓丝两端较直的部分(每段2 cm)放入EP树脂管中,加入已调节好pH值的人工唾液1 mL,保存置37 ℃电子恒温箱,在1、7、28 d时分别取出弓丝样本后测试试管中钛离子的析出量,进行统计学分析。结果:第1天时4种品牌镍钛正畸弓丝钛离子的析出量最大,7、28 d时钛离子的析出量平均后,均要少于弓丝浸泡第1天时的析出量,不同品牌间钛离子的析出量的差别不具有统计学意义。结论:4种品牌的镍钛正畸弓丝具有良好的抗腐蚀性,但是酸性环境可以加速镍钛正畸弓丝中钛离子的析出量影响镍钛正畸弓丝的抗腐蚀性。     

正畸弓丝在模拟牙矫治实验中的力学性能测定

本文通过模拟上颌前牙矫治实验，测定了目前国内常用几种弓丝的弹性性能。结果显示不锈钢类弓丝刚度大，其中澳丝刚度最大。镍钛丝和带垂直曲的弓丝刚度小，能提供较持续的矫治力。0．014中国镍钛丝具有超弹性性能，而0．016中国镍钛丝在0～250g范围内未显示出超弹性。     

钛镍方丝正畸弓丝调节器的临床应用

钛镍方丝矫正器是一种高性能、回弹性好、具有形状记忆效应的牙齿矫正器,对各种类型的牙牙合畸形具有良好的矫治效果[1]。但是,在扩大牙弓,解除拥挤,打开咬合或矫治开牙合时需要在弓丝两侧各焊接一个“U”型簧,才能行使其功能[2,3]由于焊接处理,使U型簧焊接处的弓丝会变软而失去弹性,并易折断而影响矫治效果。因此,作者根据正畸需要,设计一种钛镍方丝正畸弓丝固定调节器,并应用于临床,报告如下。1钛镍方丝正畸弓丝固定调节器的组成弓丝1根、滑套2个、螺栓2个。在弓丝上安装2个滑套滑套通过螺栓固定,使用时将一端螺栓拧松,使滑套沿弓丝滑动,…     

镍钛合金弓丝机械性能的研究进展

镍钛合金弓丝自引入正畸临床以来,以其优良的性能得到了迅速地应用和推广,其机械性能及其影响因素的研究一直备受学者们的关注。下面就近年来有关镍钛合金弓丝机械性能测定及其相关影响因素的研究作一综述。     

In vitro biocompatibility of nickel-titanium esthetic orthodontic archwires

Objective:To investigate the cytotoxicity of nickel-titanium (NiTi) esthetic orthodontic archwires with different surface coatings.Materials and Methods:Three fully coated, tooth-colored NiTi wires (BioCosmetic, Titanol Cosmetic, EverWhite), two ion-implanted wires (TMA Purple, Sentalloy High Aesthetic), five uncoated NiTi wires (BioStarter, BioTorque, Titanol Superelastic, Memory Wire Superelastic, and Sentalloy), one β-titanium wire (TMA), and one stainless steel wire (Stainless Steel) were considered for this study. The wire samples were placed at 37°C in airtight test tubes containing Dulbecco’s Modified Eagle’s Medium (0.1 mg/mL) for 1, 7, 14, and 30 days. The cell viability of human gingival fibroblasts (HGFs) cultured with this medium was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Data were analyzed by a two-way analysis of variance (α  =  .05).Results:The highest cytotoxic effect was reached on day 30 for all samples. The archwires exhibited a cytotoxicity on HGFs ranging from “none” to “slight,” with the exception of the BioTorque, which resulted in moderate cytotoxicity on day 30. Significant differences were found between esthetic archwires and their uncoated pairs only for BioCosmetic (P  =  .001) and EverWhite (P < .001).Conclusions:Under the experimental conditions, all of the NiTi esthetic archwires resulted in slight cytotoxicity, as did the respective uncoated wires. For this reason their clinical use may be considered to have similar risks to the uncoated archwires.     

Flexural properties of rectangular nickel-titanium orthodontic wires when used as ribbon archwires

Objective:To compare the flexural properties of rectangular nickel-titanium (Ni-Ti) orthodontic wires in occlusoapical and faciolingual orientations using a standardized test method.Materials and Methods:Twenty-two rectangular Ni-Ti wire groups were tested in occlusoapical (ribbon) orientation: eight conventional Ni-Ti products, five superelastic Ni-Ti products, and nine thermal Ni-Ti products (n = 10 per group). Six products of thermal Ni-Ti wire were tested in faciolingual (edgewise) orientation. A three-point bending test was performed to measure deactivation force at 3.0-, 2.0-, 1.0-, and 0.5-mm deflections of each rectangular wire at 37.0 ± 0.5°C. Analysis of variance and post hoc Student-Newman-Keuls tests were used to compare the mean values of the different groups (α = .05).Results:The ranges of deactivation forces varied greatly with different kinds, sizes, products, and deflections of Ni-Ti wires. One product of conventional and superelastic Ni-Ti wires had steeper force-deflection curves. Four products had similarly shaped flat force-deflection curves, whereas the sixth product had a moderately steep force-deflection curve. Thermal Ni-Ti wires had smaller deactivation forces ranging from 0.773 N (78.8 g) to 2.475 N (252.4 g) between deflections of 1.0 and 0.5 mm, whereas wider ranges of force from 3.371 N (343.7 g) to 9.343 N (952.7 g) were predominantly found among conventional Ni-Ti wires between deflections of 3.0 and 2.0 mm.Conclusions:Clinicians should critically select archwires for use in the occlusoapical orientation not only based on Ni-Ti wire type, size (0.022 × 0.016-in or 0.025 × 0.017-in), and product but also with deactivation deflections from 0.5 and 1.0 mm to obtain light forces in the occlusoapical orientation.     

R-相热处理镍钛根管锉的力学性能和根管预备成形能力

镍钛根管锉在根管治疗中的应用越来越广泛,为了提高镍钛根管锉的机械性能,R-相热处理技术被应用于其生产加工.本文对R-相热处理镍钛根管锉的制造工艺、弯曲性能、疲劳性能、扭转性能及预备成形能力等方面进行综述.     

前牙内收阶段不锈钢方丝机械性能的变化

目的 研究滑动法内收前牙阶段不锈钢方丝机械性能的变化.方法 选择GAC、3M、TP、TOMY4种0.019英寸×0.025英寸不锈钢方丝.使用不同时间后的方丝取自恒牙早期拔牙矫治的前牙内收阶段,截取其两侧尖牙远中区域作为检测样本.选择弹性模量、屈服强度、挠度作为评价方丝机械性能的指标.结果 前牙内收阶段4种不锈钢方丝使用4周、8周、12周、16周及20周期间,弹性模量、屈服强度及挠度变化均无显著性意义(P＞0.05).结论 前牙内收阶段4种不锈钢方丝使用20周期间,机械性能变化无显著性意义,可作为维持性弓丝起良好的稳定和引导作用.     

Shaping ability of ProTaper nickel-titanium files in simulated resin root canals

AIM: To determine the shaping ability of ProTaper instruments in simulated root canals. METHODOLOGY: Forty canals with four different shapes in terms of angle (20 degrees and 40 degrees) and position of curvature (straight section before curve: 8 and 12 mm) were enlarged according to the recommendations of the manufacturer with the finishing files F1, F2 and F3 to full working length. Preoperative and postoperative pictures, recorded using a digital camera, were superimposed and aberrations recorded. Measurements were carried out at five different points: at the canal orifice (O); half-way to the orifice in the straight section (HO); beginning of the curve (BC); apex of the curve (AC); end-point (EP). RESULTS: Ten instruments deformed (nine F3 and one S1, all in canals with straight section of 8 mm), one instrument fractured. There were significant differences between the various canal shapes for the amount of resin removed from the inner curve at all points (O: P < 0.05; HO: P = 0.001; BC, AC and EP: P < 0.001); and for the resin removed on the outer curve at points HO, AC and EP (P < 0.001). Mean transportation was towards the inner aspect of the curve in all canal types at points BC, towards the outer aspect at the end-point of preparation (EP) in all canals with 12 mm straight section. In 8 mm straight section canals, four danger zones were found; in 12 mm straight section canals three zips were present. The canal aberrations were produced following the use of the F2 and F3 instruments. There were no aberrations following the use of the F1 instrument. CONCLUSIONS: Under the conditions of this study, ProTaper instruments performed acceptable tapered preparations in all canal types. When using F2 and F3 in curved canals, care should be taken to avoid excessive removal at the inner curve, leading to danger zones. In addition, care should also be taken to avoid deformation of the F3 instrument.     

Bending properties of a new nickel-titanium alloy with a lower percent by weight of nickel

Introduction

The aim of the present study was to evaluate the bending properties of Hyflex instruments, which exhibit a lower percent in weight of nickel (52 Ni %wt) and compare them with other commercially available nickel-titanium (NiTi) rotary instruments.

Methods

Ten instruments with tip size 25, 0.06 taper of each of the following NiTi rotary instrumentation techniques were selected for the study: Hyflex, EndoSequence, ProFile, Hero, and Flexmasters. All instruments from each group were tested for stiffness by comparing their bending moment when they attained a 45-degree bend. Experimental procedures strictly followed testing methodology described in ISO 3630-1. All data were recorded and subjected to statistical evaluation by using analysis of variance test. Statistical significance was set at P < .05).

Results

Statistical analysis of the data revealed that Hyflex files were found to be the most flexible instruments, with a significant difference (P < .05) in comparison with the other instruments. Among the other files, a significant difference has been reported for EndoSequence instruments compared with ProFile, Hero, and FlexMaster (P < .05), whereas no significant differences have been reported among those 3 files (P > .05).

Conclusions

Results of the present study have illustrated an increased flexibility of the new NiTi alloy over conventional NiTi alloy, and they highlight the potential of the new manufacturing process.