反复熔铸对NEO钴铬烤瓷合金金瓷结合性能的影响

背景:NEO钴铬烤瓷合金不含有害物质,但其钴铬烤瓷合金能否回收利用存在争议,反复熔铸对NEO烤瓷合金性能影响的报道较少。目的:观察反复熔铸对NEO钴铬烤瓷合金金瓷结合力、金相结构、金瓷界面形貌的影响。方法:根据ISO9693标准,采用真空条件下氩气保护加压铸造方法,用三点弯曲实验测试分别经过1～5次熔铸后NEO钴铬烤瓷合金的金瓷结合能力,金相显微镜观察各代铸件金相结构,扫描电镜观察各代试件金瓷结合界面形貌。结果与结论:分别经过1～5次熔铸后的NEO钴铬烤瓷合金的金瓷结合能力差异有显著性意义(P<0.05);随着熔铸次数增加铸件的树枝状结构和晶粒结构逐渐模糊、消失;试件金瓷界面结合逐渐疏松、过渡层厚度增加。提示经过反复熔铸的NEO会明显影响其金瓷结合性能。     

激光焊接新型钴铬合金的力学性能

背景：新型钴铬合金为一种不含镍和铍等有害成分的齿科合金材料,但关于其激光焊接的研究尚未见报道。目的：分析新型钴铬合金的激光焊接参数,优选激光焊接电压条件。方法：铸造0.5mm×6mm×30mm的新型钴铬合金试件60个,将试件分成6组。1组作为对照组;5组试件从中间断开,进行激光焊接,光斑直径设定为0.6mm,脉冲持续时间10ms,电压分别为220,250,280,310,340V,焊后进行拉伸强度测试,记录拉伸强度和延伸率。结果与结论：激光焊接新型钴铬合金拉伸强度随电压升高而增加。延伸率在电压低于280V时,随电压增大而增加;高于280V时,随电压增大而降低。电压为280V时,激光焊接新型钴铬合金的拉伸强度为（679.94±46.87）MPa,延伸率为（5.91±0.38）%。提示电压280V,脉冲持续时间10ms,光斑直径0.6mm条件下激光焊接新型钴铬合金的拉伸强度和延伸率均能满足临床要求。     

激光焊接新型钴铬合金的力学性能

背景:新型钴铬合金为一种不含镍和铍等有害成分的齿科合金材料,但关于其激光焊接的研究尚未见报道。目的:分析新型钴铬合金的激光焊接参数,优选激光焊接电压条件。方法:铸造0.5mm×6mm×30mm的新型钴铬合金试件60个,将试件分成6组。1组作为对照组;5组试件从中间断开,进行激光焊接,光斑直径设定为0.6mm,脉冲持续时间10ms,电压分别为220,250,280,310,340V,焊后进行拉伸强度测试,记录拉伸强度和延伸率。结果与结论:激光焊接新型钴铬合金拉伸强度随电压升高而增加。延伸率在电压低于280V时,随电压增大而增加;高于280V时,随电压增大而降低。电压为280V时,激光焊接新型钴铬合金的拉伸强度为(679.94±46.87)MPa,延伸率为(5.91±0.38)%。提示电压280V,脉冲持续时间10ms,光斑直径0.6mm条件下激光焊接新型钴铬合金的拉伸强度和延伸率均能满足临床要求。     

反复熔铸镍铬合金在腐蚀液中的镍离子析出

背景:重复熔铸镍铬烤瓷合金是否会加大镍离子的析出,从而降低抗腐蚀性能,研究结论不一。目的:检测非真空状态下反复熔铸镍铬烤瓷合金在人工唾液中镍离子的析出量,分析熔铸次数对合金抗腐蚀性能的影响。方法:非真空状态下反复熔铸镍铬烤瓷合金Ⅰ、Ⅱ、Ⅲ、Ⅳ代,将试件浸泡于按照ISO标准制定的pH值为6.8,4.0的人工唾液中(168±1)h,恒温(37±1)℃,利用Z-5000原子吸收分光光度计检测不同pH值人工唾液中镍离子的析出量。结果与结论:相同pH值状态下,经两两比较发现,4代Ni-Cr烤瓷合金差异均有显著性意义(P<0.05),铸造第Ⅳ代镍离子析出最多,其次为Ⅲ代、Ⅱ代。随pH值的降低,合金的抗腐蚀性能降低,镍离子析出增多。提示非真空条件下反复熔铸镍铬烤瓷合金的耐腐蚀性能下降,随着熔铸次数的增加,镍离子的析出明显增多。     

反复熔铸镍铬合金在腐蚀液中的镍离子析出

背景：重复熔铸镍铬烤瓷合金是否会加大镍离子的析出,从而降低抗腐蚀性能,研究结论不一。目的：检测非真空状态下反复熔铸镍铬烤瓷合金在人工唾液中镍离子的析出量,分析熔铸次数对合金抗腐蚀性能的影响。方法：非真空状态下反复熔铸镍铬烤瓷合金Ⅰ、Ⅱ、Ⅲ、Ⅳ代,将试件浸泡于按照ISO标准制定的pH值为6.8,4.0的人工唾液中（168±1）h,恒温（37±1）℃,利用Z-5000原子吸收分光光度计检测不同pH值人工唾液中镍离子的析出量。结果与结论：相同pH值状态下,经两两比较发现,4代Ni-Cr烤瓷合金差异均有显著性意义（P〈0.05）,铸造第Ⅳ代镍离子析出最多,其次为Ⅲ代、Ⅱ代。随pH值的降低,合金的抗腐蚀性能降低,镍离子析出增多。提示非真空条件下反复熔铸镍铬烤瓷合金的耐腐蚀性能下降,随着熔铸次数的增加,镍离子的析出明显增多。     

反复熔铸对镍铬烤瓷合金化学成分和微观组织结构的影响

背景:熔铸后烤瓷合金能否回收再利用取决于熔铸后烤瓷合金的化学成分、微观组织结构、铸流率、力学性能、金瓷结合性能等因素的变化情况,但目前研究反复熔铸后镍铬烤瓷合金化学成分及微观组织结构的报道较少.目的:分析反复熔铸对镍铬烤瓷合金化学成分、微观组织结构变化的影响.设计、时间及地点:医学材料学体外观察实验,于2007-06/08在福建医科大学附属口腔医院技工室、福州大学材料测试中心进行.材料:以经0～5次熔铸后的镍铬烤瓷合金为原料在真空加压氩气保护铸造机铸造,即获得分别经1～6次熔铸后直径为30.0 mm、厚度为1.0 mm和边长为10.0 mm、厚度为1.0 mm的试样,依次称为Ⅰ～Ⅵ代试样,同时将厂家提供的原始合金加工成相同的形状称为0代试样.方法:应用X射线荧光光谱仪对镍铬烤瓷合金原始合金和反复熔铸后铸成的各代试样进行定性半定量分析.应用正置式反射金相显微镜对经过表面抛光后的镍铬烤瓷合金原始合金和反复熔铸后铸成的各代试样的金相显微结构进行观察;应用X射线粉末衍射仪对镍铬烤瓷合金原始合金和反复熔铸后铸成的各代试样进行物相分析.主要观察指标:各代试件中各化学成分的含量;金相显微镜下观察各代试件有无夹杂物,有无缩松、缩孔等现象;各代试件X射线峰分布情况.结果:在真空加压氩气保护的铸造环境下,经反复熔铸后,镍铬烤瓷合金的主要组分Ni、Cr、Mo、Al、Be等元素所占的质量百分数没有显著性变化,且符合相关标准要求;其金相结构为树枝状共晶结构,随着反复熔铸次数的增加,出现枝晶粗化、枝晶排列稍显紊乱、晶间相(基质)增多现象,且合金内部夹杂物的含量以及缩孔、缩松的数量分布随着反复熔铸次数的增加而逐渐增多、增广;其相结构为镍基固溶体、面心立方(FCC)晶格结构,铬元素广泛分布于镍基质中,经1～6次反复熔铸后的镍铬烤瓷合金的物相结构没有发生变化,未出现新相.结论:在真空加压氩气保护的铸造环境下,镍铬烤瓷合金各主要元素组分的质量百分数和物相结构随着反复熔铸次数的增多没有发生显著变化,随着熔铸次数的增多其枝晶粗化,合金内部夹杂物和铸造缺陷增多.     

自制钴铬烤瓷合金的金瓷结合性能

背景：在非贵金属烤瓷合金中,钴铬烤瓷合金在生物相容性、耐腐蚀性以及金属稳定性方面都优于镍铬烤瓷合金和含钛烤瓷合金,被广泛的应用于临床。目的：通过与德国BEGO钴铬合金对比,评价自制钴铬烤瓷合金的金瓷结合性能。方法：制作25mm×3mm×0.5mm规格的德国BEGO钴铬合金与自制钴铬烤瓷合金两种合金的金属试条,分别熔附8mm×3mm×1mm的VITAMK95瓷粉,采用三点弯曲的方法测试金瓷结合力,利用扫描电镜观察金属氧化界面。结果与结论：加力后国产和德国BEGO钴铬合金样本随着力量的增加瓷层开裂同时完全脱落,表面成灰黑色氧化膜,无明显瓷残余;自制钴铬烤瓷合金与德国BEGO钴铬合金的金瓷结合力差异无显著性意义[（41.26±2.68）,（41.35±2.59）MPa,P〉0.05]。说明自制钴铬烤瓷合金的金瓷结合强度高于ISO所要求的基本值25MPa,且与德国BEGO钴铬合金相比无差异,可满足临床要求。     

自制钴铬烤瓷合金的金瓷结合性能

背景:在非贵金属烤瓷合金中,钴铬烤瓷合金在生物相容性、耐腐蚀性以及金属稳定性方面都优于镍铬烤瓷合金和含钛烤瓷合金,被广泛的应用于临床.目的:通过与德国BEGO 钴铬合金对比,评价自制钴铬烤瓷合金的金瓷结合性能.方法:制作25 mm×3 mm×0.5 mm规格的德国BEGO 钴铬合金与自制钴铬烤瓷合金两种合金的金属试条,分别熔附8 mm×3 mm×1 mm的VITA MK 95 瓷粉,采用三点弯曲的方法测试金瓷结合力,利用扫描电镜观察金属氧化界面.结果与结论:加力后国产和德国BEGO 钴铬合金样本随着力量的增加瓷层开裂同时完全脱落,表面成灰黑色氧化膜,无明显瓷残余;自制钴铬烤瓷合金与德国BEGO 钴铬合金的金瓷结合力差异无显著性意义[(41.26±2.68),(41.35±2.59) MPa,P > 0.05].说明自制钴铬烤瓷合金的金瓷结合强度高于ISO 所要求的基本值25 MPa,且与德国BEGO 钴铬合金相比无差异,可满足临床要求.     

非贵金属烤瓷基底口内喷砂对瓷修补树脂黏结强度的影响

背景:已有国内外学者对崩瓷后暴露瓷面的处理与黏结进行了实验研究.然而,临床观察中发现,大部分崩瓷病例均伴有不同程度的金属基底暴露,而且,对于临床广泛应用的非贵金属烤瓷基底--镍铬、钴铬合金,其表面处理与树脂黏结的研究较少.目的:探讨口内喷砂对非贵金属烤瓷基底表面粗糙度与瓷修补树脂黏结强度的影响.方法:将镍铬合金试件与钴铬合金试件随机分为镍铬组、镍铬喷砂组、钴铬组、钴铬喷砂组.口内喷砂后,测定各组试件表面粗糙度.采用Clearfil Repair瓷修补系统进行树脂黏结修复,经37℃恒温水浴24h后,测定各组剪切黏结强度.体视显微镜观察断裂模式,扫描电子显微镜观察断裂试件的表面形貌.结果与结论:镍铬喷砂组、钴铬喷砂组粗糙度值、剪切黏结强度显著高于镍铬组、钴铬组,钴铬喷砂组粗糙度值显著高于镍铬喷砂组(P<0.05).体视显微镜下观察到镍铬组与钴铬组试件全部表现为黏结破坏,而镍铬喷砂组与钴铬喷砂组的小部分试件呈现黏结破坏与树脂内聚破坏共存的混合破坏模式.扫描电镜观察显示,镍铬组与钴铬组试件的树脂-金属断裂面仅有少量树脂残留,而镍铬喷砂组与钴铬喷砂组则观察到较多嵌入的树脂残留.提示口内喷砂能有效增强非贵金属烤瓷基底的表面粗糙度与瓷修补树脂黏结强度.     

新型钴铬合金与高金合金边缘适合性和金瓷结合强度的比较

背景：钴铬合金不含镍和铍等有害元素,且增加了钼和硅的含量,被认为适宜烤瓷使用,但关于其边缘适合性和金瓷结合性能等方面均未见相关报道。目的：比较高金合金和新型钴铬合金烤瓷冠边缘适合性和金瓷的结合强度。方法：金瓷冠预备体可卸代型24个,分为两组,一组为高金合金组,一组为新型钴铬合金组,分别制作金合金和新型钴铬合金基底烤瓷冠各12个,羧酸锌水门汀黏固。应用体式显微镜测量边缘浮出量,后将样本置于自制套管内,采用万能拉伸实验机测量崩瓷时的载荷力值。结果与结论：高金合金组唇侧边缘间隙、舌侧间隙均稍高于新型钴铬合金组,但差异均无显著性意义（P〉0.05）,崩瓷时的载荷力值稍低于新型钴铬合金组,但差异无显著性意义（P〉0.05）。说明从边缘适合性和金瓷结合角度来看,新型钴铬合金较适合烤瓷用。     

两种镍铬烤瓷合金的致突变性观察

实验对自制镍铬烤瓷合金和含铍镍铬合金的致突变性进行检测和比较.选取健康小白鼠64只,随机分为8组,即阴性对照组(生理盐水),阳性对照组(环磷酰胺,40mg/kg),自制镍铬烤瓷合金高剂量(0.769 g/L)、中剂量(0.390g/L)、低剂量组(0.077 g/L)组,含铍镍铬合金高、中、低剂量组(剂量同镍铬烤瓷合金组),每组8只.采用腹腔注射给药(25 μL/g).24 h后以同样剂量第2次注射,给药后6 h麻醉下处死采集骨髓.在油镜下用双盲法计数1 000个嗜多染红细胞的微核细胞数.结果两种样品之间及与阴性对照组相比骨髓细胞的微核率差异均无显著性(P＞0.05);样品组与阳性对照组数据相比差异均有显著性(P＜0.000 1);表明两种镍铬烤瓷合金均不具有明显致突变作用,可作为金属烤瓷冠的基底材料.     

The development of titanium and its alloys

Titanium is now an established engineering material. The current state of the technology is described, plus its uses in aerospace and other markets.     

Titanium alloys for hip joint replacements

Pure titanium and titanium-base alloys are known to be the most corrosion resistant and biocompatible of all implant materials in the body. Pure titanium is preferably used for hip cup shells with polyethylene inserts. The high strength Ti-6AI-4V alloy is mainly used for anchorage stems of femoral components with wear-resistant CoCrMo metal or Al₂O₃ ceramic ball heads. Two new high-strength titanium alloys for implants, developed by Zwicker (Ti-5AI-2.5Fe) and by Semlitsch (Ti-6AI-7Nb) in the last decade, are already in clinical use.     

Applications of shape memory alloys in medical instruments

Endosmart GmbH was founded in January 2002 and is a spin‐off from the Forschungszentrum Karlsruhe. Endosmart focuses on the use of NiTi mostly outside the implant market. Therefore a lot of tools especially for instruments for minimally invasive surgery are being developed. Innovative hingeless graspers, baskets, flexible instruments and also parts of instruments, just to name a few of them. A new focus of our work is the excellent compatibility to magnetic resonance imaging (MRI) systems, and this has led to the development of the first MRI compatible needles for use in a surgical robot. New in the field of NiTi is the porous foam and its compatibility to human cells and first results show new possibilities in growing artificial cells. In combination with the elasticity of the foam a new generation of e.g. medical bone implants could be possible. This paper describes several developments in the field of instruments of shape memory alloys (SMAs) made also at Endosmart.     

镁锌合金在动物体内降解及其相容性

背景:研究发现镁离子可以促进成骨细胞的生长,但镁合金存体内的相容性和降解性尚不清楚.目的:观察镁锌合金在动物体内的生物相容性及其在体内降解和新骨形成情况.设计、时间及地点:随机对照动物实验,于2008-03/11在上海交通大学附属第六人民医院动物实验室完成.材料:镁锌合金棒由上海奥芮济材料和医学技术有限公司提供,含镁94%,含锌6%.聚丙交酯棒由京同公司提供.方法:48只新西兰大白兔随机分成镁锌合金组和聚丙交酯组,每组24只.在左侧股骨髁钻成直径0.45 cm,长1 cm的孔,分别植入镁锌合金棒和聚丙交酯棒.主要观察指标:植入前第1天,植入后第1天、第1,2,5,10周测镁锌合金组动脉血镁离子,镁锌合金组和聚丙交酯组白蛋白、碱性磷酸酶、钤丙转氨酶、尿酸、肌酐水平.植入后3,6,12,18周植入材料部位拍摄X射线片,摄片后取股骨髁,脱钙后苏水精伊红染色组织学观察和骨量分析.结果:镁锌合金组各血清学指标存第1周内均有不同程度提高,但第2周开始下降,变化无显著性意义.两组其他各生化指标变化芹异无显著性意义.X射线片在3周显示镁锌合金组材料旁有气体产生,6周发现有成骨.12周时骨密度明显增加,12周气体自行消失.而聚丙交酯组无气体产生,有成骨.18周时镁锌合金组成骨多于聚丙交酯组(P<0.05).结论:镁锌合金在动物体内降解时有新骨替代形成,具有良好的生物相容性.     

镍钛形状记忆合金材料在骨科的应用

背景:目前镍钛形状记忆合金使用广泛,已应用于骨科内固定物、牙科心血管材料、神经外科、泌尿外科、胃肠外科、肝胆外科以及生殖医学等医学诸多领域.目的:就镍钛形状记忆合金在骨科各方面的应用作一综述,以阐明其在骨科的应用现状.方法:由第一作者分别以"镍钛形状记忆合金,骨折"和"Nickel titanium (NiTi) shape memory alloys,fracture"为关键词进行检索,CNKI数据库的检索时限为2002/2009,PubMed数据库(http://www.ncbi.nlm.nih.gov/PubMed)的检索时限为1963/2009,检索内容为镍钛形状记忆合金在骨科的应用.结果与结论:计算机初检得到57篇文献,阅读标题和摘要进行筛选,保留符合纳入标准的17篇归纳总结.结果显示,镍钛记忆合金不仅仅使用在四肢骨折中,近年来也使用在脊柱和股骨头骨折中.镍钛记忆合金生物相容性好,并具有超弹性、低磁性、耐磨损、耐疲劳、抗腐蚀的特性,已作为一种新型内固定材料被广泛使用.     

In vivo tarnish and corrosion of copper-aluminium alloys

Restorations fabricated from two different copper-aluminium crown and bridge alloys were evaluated for surface conditions by scanning electron microscopy and energy dispersive spectroscopy after two, six, and 12 months of in vivo usage. Results showed that both a fine whitish-appearing precipitate and accumulation of organic matter on nonocclusal surfaces occurred. The fine precipitate was likely to be oxides and sulphides of copper which were easily abraded awayfrom the occlusal surfaces. Since the fine details of preplacement finishing grooves of 5 μm and less were left in detail after one year of in vivo usage, corrosion rates were reasoned to be low. Tarnish was evaluated by L¹a¹b¹ colorimetry changes on flat sample coupons held intraorally by an orthodontic design. Large changes occurred with respect to as-polished surfaces and conventional gold alloy. Both alloys indicated increased brightness and yellowness. One alloy decreased in redness (increased in greenness).     

Shape memory alloys in minimally invasive therapy

Summary

Shape memory alloys are ideally suited to minimally invasive therapy, as their shape memory and superelastic properties facilitate entry through a narrow aperture before ‘expansion’ into predetermined shapes. An increasing number of shape memory alloy devices are being designed and patented although as yet they have made little impact on minimal invasive therapeutic procedures due to the complexities of effective thermal processing and accurate transformation. Within the next few years shape memory alloy technology is likely to make a big impact on laparoscopic, endovascular and endo-scopic surgical practice.     

Novel zinc alloys for biodegradable surgical staples

BACKGROUND The development of biodegradable surgical staples is desirable as non-biodegradable Ti alloy staples reside in the human body long after wound healing, which can cause allergic/foreign-body reactions, adhesion, or other adverse effects. In order to develop a biodegradable alloy suitable for the fabrication of surgical staples, we hypothesized that Zn, a known biodegradable metal, could be alloyed with various elements to improve the mechanical properties while retaining biodegradability and biocompatibility. Considering their biocompatibility, Mg, Ca, Mn, and Cu were selected as candidate alloying elements, alongside Ti, the main material of clinically available surgical staples.AIM To investigate the in vitro mechanical properties and degradation behavior and in vivo safety and feasibility of biodegradable Zn alloy staples.METHODS Tensile and bending tests were conducted to evaluate the mechanical properties of binary Zn alloys with 0.1–6 wt.% Mg, Ca, Mn, Cu, or Ti. Based on the results,three promising Zn alloy compositions were devised for staple applications(wt.%): Zn-1.0Cu-0.2Mn-0.1Ti(Zn alloy 1), Zn-1.0Mn-0.1Ti(Zn alloy 2), and Zn-1.0Cu-0.1Ti(Zn alloy 3). Immersion tests were performed at 37℃ for 4 wk using fed-state simulated intestinal fluid(Fe SSIF) and Hank’s balanced salt solution(HBSS). The corrosion rate was estimated from the weight loss of staples during immersion. Nine rabbits were subjected to gastric resection using each Zn alloy staple, and a clinically available Ti staple was used for another group of nine rabbits. Three in each group were sacrificed at 1, 4, and 12 wk post-operation.RESULTS Additions of ≤1 wt.% Mn or Cu and 0.1 wt.% Ti improved the yield strength without excessive deterioration of elongation or bendability. Immersion tests revealed no gas evolution or staple fracture in any of the Zn alloy staples. The corrosion rates of Zn alloy staples 1, 2, and 3 were 0.02 mm/year in HBSS and 0.12, 0.11, and 0.13 mm/year, respectively, in Fe SSIF. These degradation times are sufficient for wound healing. The degradation rate is notably increased under low pH conditions. Scanning electron microscopy and energy dispersive spectrometry surface analyses of the staples after immersion indicated that the component elements eluted as ions in Fe SSIF, whereas corrosion products were produced in HBSS, inhibiting Zn dissolution. In the animal study, none of the Zn alloy staples caused technical failure, and all rabbits survived without complications. Histopathological analysis revealed no severe inflammatory reaction around the Zn alloy staples.CONCLUSION Staples made of Zn-1.0Cu-0.2Mn-0.1Ti, Zn-1.0Mn-0.1Ti, and Zn-1.0Cu-0.1Ti exhibit acceptable in vitro mechanical properties, proper degradation behavior,and in vivo safety and feasibility. They are promising candidates for biodegradable staples.     

镁合金作为生物医用植入材料的临床应用

背景:镁合金由于其良好的生物相容性,可降解性等突出优点,在生物植入材料,尤其是作为可降解硬组织植入材料领域展示了良好的应用前景.而过快的降解速度是其投入临床应用亟待解决的关键问题.目的:对近期相关文献的综合分析归纳,对镁合金作为医用植入材料的优缺点进行了综述,对生物医用镁合金材料研究的最新进展进行了总结.方法:以"magnesium; magnesium calcium alloy; biodegradable; biomaterials"及"镁;镁钙合金;可降解;生物医用材料"为关键词检索ScienceDirect数据库和中国期刊全文数据库.纳入与镁合金生物医用材料密切相关文献,保留34篇文献做进一步分析.结果与结论:镁钙及镁钙基合金是未来生物医用植入材料重要的发展方向之一,快速凝固工艺是有效改善镁合金降解速度过快问题的新方法;计算模拟方法应用于镁合金生物材料有可能从微观角度深入理解镁合金用于生物医用植入材料的相关问题;另一方面,国内镁合金生物材料研究急需从基础向临床转化.