3种烤瓷铸造合金的离子析出研究

目的 研究3种常用烤瓷非贵金属合金模拟烤瓷前、后在体外细胞培养液中离子析出的量及种类。方法 用失蜡法铸造3种常用烤瓷非贵金属合金试件,镍铬合金、钴铬合金、镍钛合金,置于DMEM体外细胞培养液中30 d后重新打磨,模拟烤瓷加热过程,之后放回DMEM体外细胞培养液中浸泡30 d,用电感耦合等离子发射光谱法(ICP-AES)观察烤瓷处理前、后3种合金离子的析出的改变,扫描电镜(SEM)对表面形态观察。结果 (1)3种合金离子析出总量依次为镍铬合金>钴铬合金>镍钛合金,(2)模拟烤瓷程序后3种合金离子析出总量减少,差异具有统计学意义(P<0.05)。结论 3种常用烤瓷非贵金属合金中,镍铬合金的离子析出量最大,生物相容性最差;烤瓷过程会促进这3种合金表面氧化膜的生成,使合金的耐腐蚀性有所增强。     

五种全冠合金铸造后的腐蚀性研究

目的 测定五种制作全冠的合金铸造后在体外细胞培养液中析出金属离子的种类及不同时间段析出的各种金属离子的量。方法 本实验用电感藕荷等离子质谱仪（ICP－MS）定量测定金属离子测试。结果 镍铬合金和钴铬合金析出离子最多银钯合金和钯合金有一定的金属离子析出，纯钛只析出微量钛离子。结论 纯钛、钯合金的耐腐蚀性最好，银钯合金次之，镍铬合金和钴铬合金的耐腐蚀性较差。     

5种抛光方法对钴铬烤瓷合金抗腐蚀性能的影响

目的 研究5种抛光方法对钴铬烤瓷合金抗腐蚀性能的影响.方法 制作30个钴铬烤瓷合金试样,随机分为5组,分别采用砂纸、金相布轮、橡皮轮、电解和化学方法进行抛光,测量试样的表面粗糙度.用浸泡实验检测试件在腐蚀液中浸泡后Co、Cr离子的析出量,并用扫描电镜观察试样浸泡前后的表面形貌.结果 电解抛光会破坏钴铬烤瓷合金试样,终止后续浸泡实验;化学抛光组表面粗糙度最大,为(0.35 ±0.09) μm,与其他组差异有统计学意义(P＜0.05).腐蚀液浸泡7d后,金相布轮抛光组试件Cr析出量最小,为(0.47 ±0.17) μg/cm2;化学抛光组试件Cr析出量最最多,为(2.34 ±0.76) μg/cm2,差异有统计学意义(P＜0.05).扫描电镜观察腐蚀液浸泡前的试件,金相布轮抛光和橡皮轮抛光可获得光滑表面,砂纸抛光和化学抛光后表面划痕明显;腐蚀液浸泡后各组表面划痕没有显著变化.结论 钴铬烤瓷合金采用金相布轮和橡皮轮抛光可获得较好的表面形貌和抗腐蚀性能,化学抛光对钴铬烤瓷合金表面形貌改善不大,其抗腐蚀性能最差.     

Ti-6Al-7Nb合金铸造后抗腐蚀性能的研究

目的：研究Ti-6Al-7Nd合金在模拟口腔环境中的电化学腐蚀行为，及铸模温度对合金抗腐蚀能力的影响。方法：制作Ti-6Al-7Nd、Ti-6Al-4V、TA2三种金属铸造试件共18个，每种金属在铸模温度为室温和300℃时各铸造一组，每组试件3个。采用阳极极化技术，在37℃人工唾液中测定其稳态电位（Ecorr)，并记录其动电位极化同线。结果：在同样的铸模温度下，两种合金的Ecorr电位相近，TA2则明显负移；三种金属的Ep值相近。随着铸模温度升高，三种材料的致钝电流密度和维钝电流密度均增大，Ep正移。但其中Ti-6Al-7Nd合金的两个电流密度小于对照组。结论：Ti-6Al-7Nd合金易于钝化，其抗电化学腐蚀能力高于纯钛，与Ti-6Al-4V合金相似。铸造温度升高会降低钛材抗腐蚀能力。     

ICP-AES法测定镍铬烤瓷合金中多元細初步研究

目的 初步探讨ICP-AES法测定镍铬烤瓷合金中除镍元素以外的其他多元素的可行性.方法 准确称取0.00899g～0.08176g样品经混酸（盐酸与硝酸体积比为7∶2）完全溶解后,优化仪器条件,以基体匹配法配制工作曲线标样,消除基体干扰,从而测定镍铬烤瓷合金中多元素（Cr、Al、Mo、Co、Be、Fe、Cu）的含量.结果 测定样品中元素含量（wt％）平均为Cr 11.90％、A1 1.895％、Mo 6.905％、Co 0.205％、Be 1.67％、Fe 0.045％和Cu0.03％;6次测定的相对标准差在0.51％～1.48％范围内,加标回收率89.72％～100.90％,仪器检出限在0.11ng/ml～9.33ng/ml之间.结论 本实验初步提示ICP-AES法可测定镍铬烤瓷合金中除镍元素以外的其他多元素的含量,且该方法简便和快速.     

三种铸造合金及其相互作用的细胞毒性评价

目的检测临床常用的钴铬合金、镍铬合金、金合金及其两两合用时的细胞毒性。方法将L-929细胞在含3种合金材料或其两两组合的浸提液中培养后,采用MTT实验评定3种材料单独应用以及两两合用时的细胞毒性。结果镍铬合金的细胞毒性高于钴铬合金和金合金,金合金的细胞毒性最小。钴铬合金和金合金分别与镍铬合金组合后,其细胞毒性较钴铬合金和金合金单独应用时增加,比镍铬合金单独应用时降低;钴铬合金与金合金组合后,其细胞毒性较钴铬合金单独应用时减小。但这3种合金单独应用和两两组合应用时细胞毒性的差异均无显著性（P〉0.05）。结论 3种合金及其两两相互作用时仅具有极微弱的细胞毒性,在临床应用允许范围内。     

反复铸造对镍铬烤瓷合金热膨胀系数的影响

目的研究反复铸造对镍铬烤瓷合金热膨胀系数的影响。方法根据热膨胀仪制样要求,采用真空加氩气保护加压铸造方法,将厂家提供的镍铬烤瓷合金和已分别经过1～4次铸造的镍铬烤瓷合金制成两端平行、直径（5.5±0.05）mm、长度（25.0±0.05）mm的金属棒试件。根据ISO 9693测试标准,在热膨胀仪上测定各试件的热膨胀系数。将测试结果进行统计学分析。结果分别经过1～5次铸造的镍铬烤瓷合金之间的热膨胀系数无统计学差异（P=0.384）。经过2～5次反复铸造的镍铬烤瓷合金的热膨胀系数与经过1次铸造的镍铬烤瓷合金的热膨胀系数之间无显著性差异。结论经过2～5次反复铸造的镍铬烤瓷合金的热膨胀系数仍符合临床要求。     

ICP-AES检测NiCrBe合金在不同介质中离子析出的研究

目的：体外定量检测牙科NiCrBe合金材料离子析出的情况，分析不同浸泡液的影响，为牙科合金的临床应用提供参考。方法：电感耦合等离子体原子发射光谱仪(ICP-AES)分别检测浸泡于生理盐水或人工唾液中不同时间段的离子析出量。结果：镍离子在盐水中析出量多于人工唾液中的析出量。析出量随浸泡时间延长而增多，两组中1，3，7d析出量无显著差异，但第85d析出量明显增多。结论：浸泡时间与浸泡液种类都是影响合金材料离子析出的重要因素。长时间段离子析出的检测可预测合金的远期生物相容性。     

Ti-6Al-7Nb合金铸造后抗腐蚀性能的研究

Ti—6Al-7Nb合金作为整形外科人工植入材料，经15年临床观察发现具有良好的生物相容性。本项研究采用阳极极化技术，模拟口腔环境，将其与Ti-6Al-4V合金和纯钛作比较，评价Ti-6Al-7Nb合金的体外电化学腐蚀行为，探讨其能否用作齿科支架钛合金材料。     

三种不同烤瓷合金电化学腐蚀的试验研究

目的:研究不同烤瓷合金在人工唾液中的电化学行为,从而为临床应用提供依据.方法:采用铸造方法制作牙科合金试样,分别为:镍铬合金试件8个,镍铬合金镀金试件8个,金合金试件8个.在人工唾液中测定试件的自腐蚀电位,并测定其极化曲线.结果:自腐蚀电位以金合金试件最高,镍铬合金试件次之,镍铬合金镀金试件最低.极化曲线结果表明镍铬合金镀金试件和金合金试件具有较大的钝化区域,而镍铬合金试件的钝化区间则较小.结论:从电化学表现看,镍铬合金镀金耐腐蚀性不优于镍铬合金,二者均不如金合金.     

In vitro corrosion resistance of high-palladium dental casting alloys.

OBJECTIVE: The objective of this study was to characterize the in vitro corrosion behavior of five high-palladium dental alloys in two media using a potentiodynamic polarization technique. METHODS: Potentiodynamic cyclic polarization between -1000 and +1000 mV (SCE), 12 h open-circuit potential measurement, and linear polarization were performed on cast specimens of three Pd-Cu-Ga alloys and two Pd-Ga alloys in deaerated 0.09% NaCl solution and Fusayama artificial saliva at 37 degrees C. Zero-current potential, corrosion current density, open-circuit potential, and polarization resistance were determined. The Kruskal-Wallis test and the Mann-Whitney U-test were used to analyze the numeric findings. RESULTS: The Pd-Cu-Ga and Pd-Ga alloys in both the as-cast and heat-treated conditions showed spontaneous passive behavior under electrochemical conditions similar to those in the oral environment. The Pd-Cu-Ga alloys Liberty and Spartan Plus exhibited increased activity in the Fusayama artificial saliva after the porcelain-firing heat treatment, which may have arisen from internal oxidation of casting defects. Heat-treated Freedom Plus had an unstable oxide film to form on the surface during anodic polarization and may have a limited tendency for pitting corrosion in the Fusayama artificial saliva. The two heat-treated Pd-Ga alloys remained passive in the test media. As a group, the high-palladium alloys exhibited satisfactory corrosion resistance. SIGNIFICANCE: Corrosion of high-palladium alloys in the oral environment involves a release of ions that is related to their biocompatibility. Knowledge of the in vitro corrosion behavior of these alloys may lead to better understanding of any biologically adverse effects in vivo.     

The chloride corrosion behavior of silver-base casting alloys.

The chloride corrosion behavior of five silver-palladium dental casting alloys was investigated in a 1% NaCl solution through the use of electrochemical hysteresis technique. The corrosion mechanism has been interpreted in terms of the microstructure of these alloys and their possible electrochemical reactions.     

牙科合金腐蚀行为的研究进展

牙科合金正成为口腔科学研究和临床应用中的热点.随着对牙科合金与口腔组织相互作用的深入了解,对合金材料的物理性能和生物相容性等提出了更高的要求,目前正力求研发选择更加适应口腔多变环境的材料.牙科合金在严苛的口腔环境中会发生腐蚀,并引起美学性能、力学性能和生物相容性的下降.因此,了解牙科合金的腐蚀行为并据此进行材料的研究和...     

A technique for characterizing casting behavior of dental alloys

A technique for characterizing casting behavior of dental alloys has been developed and tested. The method employs easily reproducible specimen patterns and uses equipment and procedures generally available in dental prosthetic laboratories. A castability value is arrived at by counting complete segments of a cast alloy grid. Test results indicate that the castability evaluation procedure described can be a valuable aid in the laboratory for both selecting and using dental materials for producing cast restorations. The test method would also appear useful for the evaluation of products and techniques during research and development. An absolute minimum for the castability value determined relative to clinical and laboratory efficacy has yet to be established.     

Effect of mucin on the corrosion behaviour of dental casting alloys

The influence of mucin on the corrosion behaviour of seven typical dental casting alloys was investigated. A commercial saliva substitute (Saliva Orthana) containing mucin, and a control from which the mucin had been removed, were used. The electrochemical behaviour of the test alloys was evaluated around the open circuit potential (OCP) utilizing standard potentiodynamic techniques, as a function of oxygen concentrations and pH. The results of the corrosion measurements were analysed by a four-way ANOVA to detect the influence of alloy, environment and possible interactions. Mucin seems to act as a cathodic inhibitor at pH 6.7 but not at pH 4.6. An unidentified component (e.g. benzoate) of the saliva substitute probably acts as an adsorption inhibitor. Anodic passivation is also correlated with the artificial saliva composition.     

Galvanic corrosion behavior of implant suprastructure dental alloys.

OBJECTIVE: The purpose of this study was to evaluate and compare in vitro, the galvanic corrosion behavior of Co-Cr alloys (R2000, R800), Ni-Cr (RCS), silver-palladium (Jelstar), Gold (Pontallor-4) and Ternary Ti (experimental Ter Ti) when coupled with endosseous Ti implant abutment material. Amalgam alloy and commercially pure Ti cylinders (SSTi) were coupled with endosseous Ti implants as negative and positive controls, respectively. METHODS: An EG&G Model 263 Scanning Potentiostat was used for this purpose. Specimens were prepared and fresh artificial saliva was used as an electrolyte solution. The experiment run time was 24h for each couple. The common potential, galvanic current and current integration during the last 6h were recorded for each couple. RESULTS: The results showed that the best couples were Ti/Pontallor-4, Ti/Ter Ti, Ti/R800 and Ti/Jelstar. The least acceptable couples were Ti/amalgam, SSTi/SSTi and Ti/R2000, while the Ti/RCS couple showed unstable galvanic corrosion behavior. SIGNIFICANCE: It is concluded that the following alloys can be used as suprastructure alloys with Ti implants: Pontallor-4, R800, Jelstar and Ter Ti. Although Ter Ti alloy is an experimental alloy, it showed good results, but cannot be used in the clinical field unless extensive investigations are carried out. The SSTi/SSTi couple showed unexpected galvanic corrosion behavior which needs further investigation.     

Alternative dental casting alloys

The diversity of alloys available to the dental practitioner has never been more extensive. We now have the opportunity to select alloys based on the individual patient's specific biologic, functional, and economic requirements. There is no one alloy suitable for all applications, because in metallurgy there is a constant trade-off in properties as changes in formulations are made. To make optimal use of the choices available, and for ethical and medicolegal considerations, it is incumbent upon the practitioner to be aware of the identity and composition of the alloys prescribed.