不同热处理对牙科铸造银钯合金腐蚀行为的影响

目的 研究不同处理对牙科用银钯铸造合金腐蚀行为的影响。方法 熔炼银钯铸造合金,参照ISO 10271:2001牙科金属材料抗腐蚀实验标准,按照标准牙科失蜡法铸造程序制作测试样本,经固溶软化处理后,分别进行相应的热处理、深冷处理、热处理并深冷处理,以固溶软化处理组作为对照组。采用金相显微镜观察分析,并行电化学实验、静态浸泡实验测试合金的电化学参数及非贵金属离子析出值。结果 各实验组的金相结构发生了变化,电化学参数的开路电位Eocp、腐蚀电位Ecorr及腐蚀电流密度Icorr与对照组的差异有统计学意义（P<0.05）,但各实验组与对照组银、钯、铜离子析出量的差异无统计学意义（P>0.05）。结论 各组的抗腐蚀性能指标均能满足ISO标准的要求,适当的热处理、深冷处理、热处理并深冷处理能改善实验合金的抗腐蚀性能。     

两种低贵金属合金的腐蚀性能实验研究

目的　评价两种牙科低贵金属合金的腐蚀性能。方法　运用动电位极化技术评价了Au -Pd -Ag ,Ag -Pd ,两种低贵合金的腐蚀性能并与Co -Cr ,Ni-Cr,Cu -Al以及Au -Pt合金比较。试验介质为fusayama人工唾液 (37 C ,pH =5 ) ,采用电子能谱扫描分析腐蚀产物。结果　自腐蚀电位EocAu-Pd -Ag和EocAg -Pd分别为 - 2 6mv ,40mv远比Ni-Cr合金 (Eoc =- 2 2 3mv)、Co -Cr合金 (Eoc =- 16 5mv)为正 ,但低于传统Au -Pt合金。极化曲线表明电位一定时 (<6 0 0mv)Au -Pd -Ag合金 ,Ag -Pd合金的电流密度比Cu -Al合金与Ni-Cr合金低 ,与传统Au -Pd合金接近。ESCA腐蚀产物拟合结果表明Au -Pd -Ag合金、Ag -Pd合金腐蚀主要以Ag为主 ,而Au、Pd均无化合物形成。结论　两种低贵合金具有良好的耐腐蚀性能 ,低贵合金腐蚀主要以Ag相腐蚀为主     

两种常用碘制剂引起口腔铸造用银铟合金表面腐蚀的初步研究

目的：研究两种常用碘制剂对口腔铸造用银铟合金的腐蚀影响。方法：制作口腔修复铸造用银铟合金测试件,对照组不与腐蚀介质接触,实验组分别浸入浓台氏液及碘甘油发生腐蚀反应,腐蚀时间设定为5sec、10sec、15sec、30sec、1min、5min、10min、30min,用X射线光电子能谱仪（x-ray ph otoelectron spectroscopy,XPS）分析银铟合金表面腐蚀产物。结果：两种常用碘制剂均引起银铟合金腐蚀,腐蚀层含有银、铟、锌、钯、碘离子。浓台氏液组不同腐蚀时间银、铟、锌、钯质量百分比结果显示：实验组与对照组相比差异有统计学意义（P〈0.05）,而各实验组间两两相比差异无统计学意义（P〉0.05）。碘甘油组不同腐蚀时间银、铟、锌、钯质量百分比结果显示：10sec组及其以后所有实验组与对照组相比差异有统计学意义（P〈0.05）,而10sec组及其以后各实验组之间两两相比差异无统计学意义（P〉0.05）。相同腐蚀时间碘甘油组银、钯、铟、锌、碘各离子质量百分比与浓台氏液组比较差异有统计学意义（P〈0.05）。结论：两种常用碘制剂均引起银铟合金的腐蚀;腐蚀与腐蚀时间不呈线性增长关系：具体表现为浓台氏液组腐蚀层银、铟、锌、钯离子含量在5sec显著减低,而碘甘油组腐蚀层银、铟、锌、钯离子含量在10sec显著减低,后随时间的增加各离子含量基本稳定;浓台氏液引起银合金表面的腐蚀变化大于碘甘油。     

牙科贵金属铸造合金现状

贵金属包括金、银和铂族元素一铂、铑、钯、铱、钌和锇。金属状态金具有美丽的黄色,锇为蓝灰色,其余6种金属均为银白色。金的熔点1063℃,银为960.5℃。除此之外,铂族元素的熔点均较高(钌2310℃,铑1966℃,钯1554℃,锇3045℃,铱2410℃,铂1772℃)。贵金属具有优异的耐腐蚀性、抗氧化性、延展性,较高的密度和良好的生物相容性。由于贵金属独特的物理、化学和生物学性能,使它们成为首选牙科合金,在世界上得到广泛应用。1 牙科贵金属合金应用状况 约在公元前2500年,金就开始用于牙科修复。本世纪初,精密铸造技术被引入牙科修复工艺,推动了贵金属在牙科中的应用,金的消费量逐年增加。70年代,金价格上涨,促进了替代合金的出现。替代合金分为二类:一类是降低金含量,代之以钯和银的低金合金,含微量金的钯基合金(主要用     

铸造用合金

<正> 口腔修复科所用的铸造合金(Asting Alloys)已有最初的元合金、二元合金增加至多达7、8种以上的元素如钴、镍、钼、钽、钛、锡等。这些元素的增加改善和提高了合金的机械性能和化学稳定性,铸造用合金根据其熔化温度分为三类:高熔合金(熔点在1100℃以上),中熔合金(熔点在500°～1000℃),低熔合金(熔点在300°～500℃)。按使用范围可分(1)铸造部分托牙支架、基板等用合金如钴铬合金,18—8不锈钢,镍钴钢合金和金铂合金等。(2)冠桥,嵌体用合金如镍铬合金,银钯合金、金合金等。(3)烤瓷用合金如金合金、镍铬合金及镍钴合金等。按经济价值又可分为贵金属合金如金合金、金铂合金等:半贵合金如银钯合金和非贵合金、如钴铬合金,镍铬合金,18—8不锈钢等。     

低贵金属含量合金铸造精度的研究

目的 对低贵金属含量合金铸造精确程度进行比较评价。方法 采用剖切法测量并比较了研制的两种低贵金属含量合金和三种临床常用非贵金属合金的冠边缘精确度。结果 两种低贵金属合金冠边缘完整、锋利,三种非贵金属合金则出现程度不等的冠边缘缺陷、边缘圆钝。边缘浮出量由小到大依次为:金钯合金、银钯合金、钴铬合金、镍铬合金、铜铝合金。结论 两种低贵金属合金的铸造精度良好,能够满足临床要求。     

碘甘油引起口腔铸造用银铟合金表面腐蚀的初步研究

目的 通过分析合金的表面腐蚀产物,考察不同腐蚀反应时间碘甘油对口腔铸造用银铟合金的腐蚀情况。方法 制作口腔修复铸造用银铟合金测试件,对照组不与碘甘油接触,实验组浸入碘甘油发生腐蚀反应,反应时间分别为5 s、10 s、15 s、30 s、1 min、5 min、10 min、30 min,以扫描电子显微镜（SEM）观察试件表面形貌,再以X线能谱分析银铟合金表面腐蚀产物。结果 SEM结果显示:腐蚀是在整个金属表面上均匀进行的。对合金表面银、铟、锌、钯等离子质量百分比进行统计分析显示:对照组与10 s组及其以后所有实验组分别相比均有显著差异（P<0.05）,而10 s组及其以后各实验组之间两两相比并无显著差异（P>0.05）。结论 腐蚀特征为均匀腐蚀。腐蚀与腐蚀时间不呈线性增长关系,具体表现为腐蚀层银、铟、锌、钯离子含量在10 s显著减低,之后随时间的增加各离子含量基本稳定。     

钯银合金耐腐蚀性能的研究

目的探讨两种钯银合金在人工唾液中的耐腐蚀性。方法制作合金标准铸件,并将其浸入人工唾液中7、30、90d,采用电感耦合等离子质谱仪测试合金浸渍液中的金属离子含量。结果钯银d.sign67合金、钯银d.sign59合金和镍铬合金在人工唾液中浸泡析出的离子量在3个时间段的差异均有统计学意义（P〈0.001）,各时间段两种钯银合金在人工唾液中析出的金属离子量明显低于镍铬合金,差异有统计学意义（P〈0.05）。各时间段的钯银d.sign67合金和钯银d.sign59合金离子析出量差异均无统计学意义（P〉0.05）。浸泡时间和合金种类之间存在交互效应（P〈0.001）。结论钯银合金耐腐蚀性好于镍铬合金。     

有关牙科合金腐蚀的研究现状

如今牙科合金被大规模应用于临床，因合金腐蚀造成的临床问题也接踵而至，如镍铬合金腐蚀后引起龈缘黑线等。通过对现有相关文献的检索、整理和分析，对影响牙科合金腐蚀的相关因素研究进展作一综述。     

不同热处理对自研新型高钯牙科合金腐蚀行为的影响

目的：评估不同热处理对自研高钯合金腐蚀行为的影响。方法将不同温度热处理后的自研高钯合金按照ISO 10271：2001/Cor.1：2005（E）标准进行电化学腐蚀实验，以商品化Spartan? Plus合金作为对照组。在电化学实验中，依次进行2 h开路电位（Eocp）测定并记录极化曲线，然后拟合出腐蚀电位（Ecorr）、腐蚀电流密度（Icorr）等相关电化学参数。同时，使用扫描电镜观察合金腐蚀前后的表面形貌。结果热处理不同程度地改善了两种合金在ISO10271电化学实验中的耐腐蚀性。其中，两种合金的500℃组电化学参数最佳，耐腐蚀性最好，但尚不能认为两者之间的耐腐蚀性能有差别。对比电化学实验腐蚀前后的试件表面形貌，两种合金的所有组别均可见腐蚀后的点蚀现象和裂隙腐蚀现象，随着热处理温度的升高，点蚀和裂隙腐蚀逐渐变少。两种合金各组间横向比较，未发现明显的点蚀和裂隙腐蚀分布的差异。结论对于高钯合金而言，高含量的钯基质相使合金的组分变化并不足以对合金的腐蚀行为产生明显改变。两种合金在耐腐蚀性方面的相似性可能归因于合金自身的高钯含量。     

New conversion method of metal surfaces for resin bonding. Conversion effects for pure metals in dental precious metal alloys

Excellent adhesion of adhesives to metals can be realized by simply applying liquid Ga-Sn alloy (Adlloy) on the adherend metal surface. This method is only effective on dental precious metal alloys. Five metals, Au, Pt, Pd, Ag, and Cu, included in dental precious metal alloys were converted by this method to determine the most effective pure metal from bonding strength measurements, water durability at the adhesion interface, and ESCA measurements. All metals converted by Adlloy showed excellent bonding strength and water durability, whereas nonconverted metals showed poor water durability. ESCA measurements showed that metal surfaces converted by Adlloy are covered with a 3-6 nm thick Ga and Sn oxide film and that the diffusibilities of Ga in the metals are in the order Ag greater than Au greater than Pt greater than Cu greater than Pd. From the viewpoint of handling, Ag is the most effective metal.     

Microstructure and corrosion behavior of binary titanium alloys with beta-stabilizing elements.

Binary titanium alloys with the beta-stabilizing elements of Co, Cr, Cu, Fe, Mn and Pd (up to 30%) and Ag (up to 45%) were examined through metallographic observation and X-ray diffractometry to determine whether beta phases that are advantageous for dental use could be retained. Corrosion behavior was also investigated electrochemically and discussed thermodynamically. Some cast alloys with Co, Cr, Fe, Mn, and Pd retained the beta phase, whereas those with Ag and Cu had no beta phase. In some alloys, an intermetallic compound formed, based on information from the phase diagram. The corrosion resistance deteriorated in the TiAg alloys because Ti2Ag and/or TiAg intermetallic compounds preferentially dissolved in 0.9% NaCl solution. On the other hand, the remaining titanium alloys became easily passive and revealed good corrosion resistance similar to pure titanium since their matrices seemed to thermodynamically form titanium oxides as did pure titanium.     

Corrosion of three experimental AgMn-based casting alloys

OBJECTIVE: Alloys based on AgMn are being evaluated in our laboratory for their possible use as an alternative to Type III dental alloys. They respond to heat treatment and develop hardness values comparable to that of Type III alloys. The objective of the present research was to evaluate their corrosion characteristics. METHODS: The three experimental silver-based alloys of the following composition (at%): (1) 63Ag37Mn, (2) 60Ag35Mn5Au and (3) 60Ag35Mn5Pd, were tested in their peak-hardened condition. Following 0.5 h open-circuit potential (OCP) measurement of each alloy in a phosphated buffer saline (PBS) solution, its current-potential profile was generated by the cyclic voltammetry technique within -1300 and +200 mV (SCE) at 1 mV s-1. In a separate test, the OCP of each alloy was monitored over a 24 h period. RESULTS: Each of the three alloys showed ennoblement of their OCP over time due to dissolution of Mn and consequent enrichment with Ag (Au or Pd). At 24 h, the two ternary alloys were the most noble followed by the binary alloy. With respect to the cyclic voltammetry, oxidation of Ag was noted during forward scans at around 0 mV. The reverse scan was associated with a reduction current peak between -37 and -128 mV. The values for this peak, which is a measure of Ag oxidation, were highest (11.5 mA cm-2) for the binary alloy followed by the Au- (2.9 mA cm-2) and Pd-containing (0.04 mA cm-2) alloys, respectively. This indicates that, for equivalent concentration, Pd is more effective in reducing Ag corrosion than Au. SIGNIFICANCE: Alloys based on the AgMn system are as hard as Type III dental alloys. Information on the corrosion characteristics of the AgMn-based alloys presented here is of value in further development of this alloy system.     

Dealloying and electroformation in high-Pd dental alloys.

OBJECTIVE: The corrosion of high-Pd dental alloys, depending on their composition, is postulated to be associated with dealloying and electroformation. The aim of this study was to obtain additional information to support these postulations. METHODS: The corrosion characteristics of two commercial high-Pd alloys, Naturelle (79Pd-10Cu-2Au-9Ga wt%) and Rx 91 (54Pd-37Ag-9Sn), and their elemental components were evaluated in a phosphated buffer saline (PBS) solution. Indium, a common element in high-Pd alloys, was also included. The corrosion characteristics measured for each material were the 24 h open circuit potential (OCP) and the potentiodynamic anodic polarization curve. Additionally, the surface composition of the two alloys, before and after immersion corrosion in PBS for 2 months, was analyzed by X-ray photo electron spectroscopy (XPS). RESULTS: Of the pure metals, Ga had the most electroactive OCP followed in order by In, Sn, Cu, Ag, Au, and Pd. The anodic polarization data showed all base metals to be unstable in PBS. The electroformation of AgCl was evidenced in the polarization curve of pure Ag. Both electrochemical characteristics of the PdCu-based alloy were very similar to that of pure Pd. The PdAg-based alloy displayed corrosion behavior resembling that of Ag. XPS data showed that the corrosion of the PdCu-based alloy was associated with a decrease in surface content of Cu and Ga but an increase in Pd and Au. The PdAg-based alloy surface during corrosion showed a decrease in Sn, an increase in Ag, and an unaltered Pd content. The behavior of the PdCu-based alloy is attributed to the operation of a galvanic interaction that causes dissolution of base metals and surface enrichment with primarily Pd. Dealloying, Ag-enrichment, and AgCl formation are thought to have contributed to the observed behavior of the PdAg-based alloy. These mechanisms are consistent with data from published ion release studies. SIGNIFICANCE: The allergenic potential of any Pd alloy is dependent on its propensity to develop a Pd-rich surface and thus release Pd+2 ions. The present study, though limited, has shown that electrochemical characteristics, namely OCP and polarization curves, can be used to identify such alloys. Further studies are warranted to evaluate the widespread applicability of these characteristics in distinguishing between Pd alloys that are biologically safe and those that are not.     

Study of the influence of the anodic potential on metal-components dissolution from dental alloys

This study aims to evaluate the influence of the anodic potential on metal-components dissolution from dental alloys and is intended to serve as an aid in the investigation of dental metal eruption (metal allergy). In the experiments, anodic potentials were applied electrochemically to various dental alloys in a 0.9% NaCl solution. Thereafter amounts of metal-component dissolution were measured by means of atomic absorption spectrophotometry. In addition, relations between metal-component dissolution and electrochemical characteristics (anodic polarization and charge transfer calculated from current density-time transients) were considered. Results: 1. Breakdown potentials determined on the basis of anodic polarization profiles agreed with potentials of remarkable increase in component dissolution. 2. Current density-time transients gave good indications of alloys' corrosion tendencies. Correlations between charge transfer and total amounts of metal-component dissolution were comparatively good. 3. Metal-component dissolutions in various alloys at fixed anodic potentials 1) Cu and Zn were found to dissolve slightly from gold alloys (types II and IV) at potentials above 200 mV (vs SCE). 2) Ag, Pd, Cu, and Zn were found to dissolve from the Ag-Pd-Cu-Au alloy at potentials above 100 mV. A comparatively large amount of Zn was released at low potentials. Amounts of Ag and Cu dissolution increased rapidly at 300 mV and 500 mV respectively. Although traces of it were detectable at low potentials, dissolution of Pd increased remarkably at 500 mV. 3) Ag, In, and Zn were found to dissolve from the Ag-In-Zn alloy at potentials above O mV. Amounts of In and Zn dissolution increased above 20 mV. The increase was especially remarkable in the case of In. 4) Sn and Zn were found to dissolve from the Ag-Sn-Zn alloy at potentials above -200 mV; Ag dissolved from the same alloy at potentials above 100 mV. Amounts of Sn and Zn dissolution increased at potentials above 100 mV. This was especially true in the case of Sn. 5) Ni, Cu and Si were found to dissolve from the soft type Ni-Cr alloy (9.0 wt% Cr) at potentials above -100 mV. Cr, Mn, and Fe dissolved from the same alloy at potentials above 0 mV; and Co at potentials above 200 mV. Metal-component dissolution was greater in the case of this alloy than in those of all the other alloys used in this study. A considerable amount fo Ni was released at 0 mV.(ABSTRACT TRUNCATED AT 400 WORDS)     

铸造合金全冠戴用后颊黏膜上皮细胞DNA损伤的研究

目的 研究3种铸造合金全冠戴用后颊黏膜上皮细胞DNA的损伤情况。方法 给狗分别进行58%金合金、不含Be元素的NiCr合金、含Be元素的NiCr合金铸造全冠修复,建立实验动物模型。采用VG-X7型电感耦合等离子体质谱仪和IRIS Intrepid型电感耦合等离子体原子发射光谱仪检测戴冠前、戴冠2周、1月、2月及3月时颊黏膜上皮细胞中金属离子的种类和质量浓度,同时应用彗星电泳方法检测颊黏膜上皮细胞DNA的损伤情况。结果 58%金合金全冠戴用后,在颊黏膜上皮细胞中金属离子质量浓度变化不明显;戴冠2周时彗星数目显著增加,而后又恢复到戴冠前水平。NiCr合金全冠戴用后,颊黏膜上皮细胞中Ni、Cr、Be离子质量浓度以及彗星数目均随着戴冠时间的延长而逐渐升高,其中含Be元素组的彗星数目显著高于不含Be元素组,而后者彗星数目又明显高于58%金合金组。颊黏膜上皮细胞中的Ni、Cr、Be离子质量浓度与彗星数目呈正相关。结论 金合金全冠戴用后没有引起颊黏膜上皮细胞DNA的损伤,而NiCr合金全冠,尤其含Be元素者,戴用后将引起颊黏膜上皮细胞DNA发生明显损伤。     

Elemental release from dental casting alloys into biological media with and without protein.

OBJECTIVE: The objective of this study was to determine the role of proteins in affecting elemental release from a variety of clinically available dental casting alloys. An important role for proteins was suspected based on previous reports about the corrosion of stainless steel and the cytotoxicity of alloys after exposure to a saline-protein solution. METHODS: Clinically available alloys with compositions ranging from 0 to 94at.% noble elements were exposed for 1 week to either saline, saline with 3% bovine serum albumin (BSA), or complete cell-culture medium with 3% serum. Atomic absorption spectrophotometry was used to measure the release of elements from the alloys. Elemental release was normalized for the exposed surface area of the alloys. RESULTS: In general, more elemental release occurred into the saline-BSA solution compared to saline alone for all released elements (Ag, Cu, Pd, and Zn) except for Ni. Ni release from the NiCr alloy was lower in the presence of BSA. Each element responded somewhat differently with Pd being the least predictable in its behavior. Elemental release was less in the cell-culture medium than in the saline-BSA solution for most elements. For alloys which released multiple elements, all elements responded similarly but not identically to the presence of protein. A high elemental release during exposure to the saline-BSA solution correlated with a low alloy cytotoxicity post-exposure to the saline-BSA. SIGNIFICANCE: This study demonstrates the importance of defining exactly the composition of biological solutions used to assess in vitro corrosion and biocompatibility of dental casting alloys. Other molecules in addition to proteins appeared to be critical to the corrosion of these alloys in vitro.     

In vitro cytotoxicity of metallic ions released from dental alloys

The cytotoxicity of a dental alloy depends on, but is not limited to, the extent of its corrosion behavior. Individual ions may have effects on cell viability that are different from metals interacting within the alloy structure. We aimed to investigate the cytotoxicity of individual metal ions in concentrations similar to those reported to be released from Pd-based dental alloys on mouse fibroblast cells. Metal salts were used to prepare seven solutions (concentration range 100 ppm–1 ppb) of the transition metals, such as Ni(II), Pd(II), Cu(II), and Ag(I), and the metals, such as Ga(III), In(III), and Sn(II). Cytotoxicity on mouse fibroblasts L929 was evaluated using the MTT assay. Ni, Cu, and Ag are cytotoxic at 10 ppm, Pd and Ga at 100 ppm. Sn and In were not able to induce cytotoxicity at the tested concentrations. Transition metals were able to induce cytotoxic effects in concentrations similar to those reported to be released from Pd-based dental alloys. Ni, Cu, and Ag were the most cytotoxic followed by Pd and Ga; Sn and In were not cytotoxic. Cytotoxic reactions might be considered in the etiopathogenesis of clinically observed local adverse reactions.     

Strength and microstructure of gallium alloys

This study investigated the physical and mechanical properties and the microstructure of four different gallium alloys. For all gallium alloys, the compressive strengths measured at one hour (86-223 MPa) and 24 hours (265-286 MPa) after specimen preparation were found to be well within the range exhibited by many high-copper amalgams. The creep values and dimensional change of the gallium alloys were comparable to those of leading amalgams, except for the dimensional change value of one alloy. The set gallium alloys consisted of a multi-phase structure including beta-Sn, CuGa2, In4Ag9, Ag72Ga28, and Ga5Pd (except for one product that did not contain Pd) that was more complicated than the structure of dental amalgams. Although the gallium alloys had physical and mechanical properties comparable to those of high-copper amalgams, the microstructure, coupled with the instability of the element gallium itself, could make these materials more prone to corrosive attack compared to amalgams.