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。     

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...     

牙科低贵合金腐蚀后表面成分分析

目的 通过分析牙科低贵合金腐蚀后的表面成份，探讨腐蚀机理。方法 运用静态浸泡试验评价Ag-Pd合金的腐蚀性能并与常用牙科修复合金Co-Cr、Cu-Al比较。腐蚀介质为Fusayama人工唾液（37℃，pH=5)。采用扫描电镜、电子能谱分析腐蚀产物。结果 铜铝合金的腐蚀大于银钯合金和钴铬合金（P＜0.05)；银钯合金主要以银和铜腐蚀为主，铜选择性释出。结论 低贵合金的腐蚀源于多相结构之间电位差引起的原电池反应。     

牙科合金腐蚀行为的电化学研究及影响因素

牙科合金在口腔环境中发生的腐蚀主要是电化学腐蚀。电化学方法是研究合金腐蚀的主要手段。合金的电化学腐蚀与材料的成分和量以及组织结构密切相关。口腔电解质溶液环境和微生物对合金的腐蚀也有显著的影响。     

六种牙科合金的电化学腐蚀研究

采用电化学腐蚀法对6种牙科合金进行了实验研究。结果显示:每秒钟释放的离子数,以铝钒钛合金最少,3种不锈钢次之,镍铬合金较多,铜合金最多。将5种合金电化学腐蚀及静置浸提后的微量元素,采用原子吸收光谱仪进行测定分析,前者的金属离子浓度均极显著地大于后者。提示电化学腐蚀能快速、定量地评价合金的抗腐蚀性。     

牙科合金的铸造性能研究进展

牙科精密铸造工艺多用熔模铸造又称失蜡铸造法 ,其基本过程是先用蜡或塑料等制成蜡型 ,蜡型表面涂敷包埋料制作铸型 ,然后熔化合金铸入铸型腔内 ,形成铸件。在这一系列过程中 ,每一个步骤都对最终的铸件完整性产生影响 ,而铸件完整性对牙科合金铸造成功与否起着关键的作用。研究牙科合金的铸造性能即研究牙科合金能够完全铸入铸型腔的能力 ,也即实际铸入铸型腔内的合金占应该铸入铸型腔内合金量的百分比 (一般用Ｃｖ即铸流率表示 )。虽然牙科合金的铸造历史很长 ,但对其铸造性能的研究方法还没有达到广泛的一致 ,总的来说研究牙科合金铸造性…     

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     

牙科合金微生物腐蚀的研究进展

随着牙科材料的发展,牙科合金如钴铬合金、镍铬合金、钛（钛合金）和贵金属（合金）在口腔修复领域的应用越来越广泛。这些金属在口腔内行使功能时,由于其所处的是一个非常复杂的电解质环境,会发生各种形式的腐蚀。口腔中的金属腐蚀主要包括化学腐蚀和电化学腐蚀两种类型,其中电化学腐蚀又有三种形式：微生物腐蚀、电偶腐蚀、应力腐蚀破裂。     

变形链球菌对牙科合金耐蚀性的影响

目的：探讨变形链球菌对镍铬合金、钴铬合金和金合金腐蚀性能的影响。方法：将3种牙科合金与变形链球菌在液体培养基中共同培养,以单纯培养基和空白组作为对照,8周后,进行电化学实验和扫描电镜观察。结果：电化学实验结果显示,镍铬、钴铬合金的自腐蚀电位绝对值及自腐蚀电流密度值均为培养基对照组低于变形链球菌组及空白对照组,且在变形链球菌组的合金表面不规则破裂孔明显增多。金合金各组自腐蚀电位和电流密度无统计学差异,金合金表面形貌无明显变化。结论：变形链球菌能增加口腔镍铬、钴铬合金的腐蚀倾向与腐蚀速率,但对金合金的影响不明显。     

激光立体成形Ti-Zr合金腐蚀性能研究

目的:评价牙科激光立体成形钛锆(Ti-Zr)合金在人工唾液环境下的电化学腐蚀性能。方法:采用激光立体成形方法制备牙科Ti-Zr合金试件,并以常规铸造Ti-Zr合金作为对照,采用动电位极化技术,在人工唾液(37℃,pH=6.8)环境中,描记极化曲线图;用扫描电镜观察电化学腐蚀后的界面,综合分析其耐腐蚀性能。结果:采用激光立体成形的钛锆试件与铸造件相比具有相对较正的自腐蚀电位、较小的自腐蚀电流密度、较低的致钝电位,并且都未出现破裂电位;扫描电镜显示激光立体成形钛锆无明显的腐蚀迹象。结论:激光立体成形钛锆(Ti-Zr)合金试件具有较好的耐腐蚀性能。     

The effect of pH on the corrosion of dental metal alloys

The aim of this study was to determine the effects of the oral environment's pH on the corrosion of dental metals and alloys that have different compositions, using electrochemical methods. The corrosion rates and the cathodic Tafel slopes were obtained from the current-potential curves. The effect of pH on the corrosion of dental metals and alloys was dependent on their composition. Dissolution of the ions occurred in all of the tested pH states. The dissolution was moderately low for samples containing titanium because its surface was covered with a protective layer, whereas the dissolution was maximal for the samples containing tin and copper. Addition of cobalt and molybdenum to the alloys improved their corrosion resistance; these cobalt and molybdenum alloys were not effected by changes in the pH. Dissolution of the precious metal alloys increased as the percentage of noble metals increased. The corrosion characteristics of dental metals and alloys are important because the corrosion tendencies of dental alloys in the mouth may cause health hazards, weakening and the aesthetic loss of dental restorations.     

钛材料在口腔生物环境中腐蚀的研究进展

钛材料在口腔医学领域的应用越来越普及,但钛材料在口腔中的腐蚀却是亟待解决的问题。钛材料的腐蚀与口腔生物环境中递质的变化以及口腔的咀嚼活动参与密切相关。下面就钛及其合金在pH值、氟化物和蛋白质以及温度变化等口腔生物环境中的腐蚀研究进展作一综述,以期为钛及其合金耐腐蚀性能的提高提供参考。     

Effects of chemical composition on the corrosion of dental alloys

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.     

Corrosion behaviour of dental metals and alloys in different media

The corrosion tendencies of metals are related with their position in the electromotive series. These electrode potential degrees may change due to the compositions of the alloys, the surrounding media, or due to alterations in the composition because of recurrent casting. Therefore in this research, the electrode potentials and their changes over a period of time were measured in different pH media simulating the oral electrochemical conditions in vitro. The surface structure of the first and second castings of 29 different dental metals and alloys were examined under a scanning electron microscope and their composition in percentage weight was calculated by the Energy-dispersive X-ray Analysor system. Further the current–potential curves of the dental alloys were found by the potentiodynamic method in three different solutions and, in addition, the changes of corrosion potentials over time were also determined. The corrosion rates, corrosion potentials, their changes over time and their cathodic Tafel slopes were determined. All alloys tested showed ion leakage in corrosive media. Titanium exhibited the least, but alloys with tin and cobalt content displayed the greatest corrosion tendencies. Alloys with iron and copper corroded in the acid media, conversely alloys containing chromium, nichel and molybdenum proved to be resistant to corrosion. The recurrent castings were also corrosion resistant.     

Use of potentiodynamic polarization technique for corrosion testing of dental alloys

Abstract— The number and in particular the diversity in types and composition of alloys used in dentistry are increasing, thus enhancing the need for predictive corrosion testing. No corrosion test is generally accepted as being both applicable to and relevant for all dental alloys. However, some methods have gained a certain recognition, and among these are the potentiodynamic polarization techniques. The purpose of the present work was to study the application, the reproducibility and the influence of some methodological variables on the results of potentiodynamic polarization corrosion testing. Embedded specimens of 18 different dental alloys, representing all major types, were subjected to anodic polarization scan within the potential range of – 700 mV to 1000 mV (SCE). Artificial saliva, with and without organic compounds, and sodium sulfide solution were used as electrolytes. The results were processed on a microcomputer using locally developed software. The curves of current density versus potential showed fair reproducibility, with great differences between some of the alloys, showing a clear relationship to nobility or passivity of the alloy. There were marked differences between the results obtained in artificial saliva and in sodium sulfide solution, while addition of organic components to the artificial saliva only had a minor effect. The potentiodynamic polarization corrosion test supplies detailed information such as anodic charge, and open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. These are all useful when evaluating the corrosion properties of a dental alloy. An analysis of variance of the results in this study showed that possible differences between the alloys were clearly detectable with this method. However, for alloys releasing non-ionic products during corrosion/degradation, the method may be inappropriate. It is thus concluded that the method appears applicable as an in vitro corrosion test for most dental alloys, with the possible exception of amalgams.     

Use of potentiodynamic polarization technique for corrosion testing of dental alloys

The number and in particular the diversity in types and composition of alloys used in dentistry are increasing, thus enhancing the need for predictive corrosion testing. No corrosion test is generally accepted as being both applicable to and relevant for all dental alloys. However, some methods have gained a certain recognition, and among these are the potentiodynamic polarization techniques. The purpose of the present work was to study the application, the reproducibility and the influence of some methodological variables on the results of potentiodynamic polarization corrosion testing. Embedded specimens of 18 different dental alloys, representing all major types, were subjected to anodic polarization scan within the potential range of -700 mV to 1000 mV (SCE). Artificial saliva, with and without organic compounds, and sodium sulfide solution were used as electrolytes. The results were processed on a microcomputer using locally developed software. The curves of current density versus potential showed fair reproducibility, with great differences between some of the alloys, showing a clear relationship to nobility or passivity of the alloy. There were marked differences between the results obtained in artificial saliva and in sodium sulfide solution, while addition of organic components to the artificial saliva only had a minor effect. The potentiodynamic polarization corrosion test supplies detailed information such as anodic charge, and open circuit, rupture, and passivation potential. Furthermore, it indicates the passive range and sensitivity to pitting corrosion. These are all useful when evaluating the corrosion properties of a dental alloy. An analysis of variance of the results in this study showed that possible differences between the alloys were clearly detectable with this method. However, for alloys releasing non-ionic products during corrosion/degradation, the method may be inappropriate. It is thus concluded that the method appears applicable as an in vitro corrosion test for most dental alloys, with the possible exception of amalgams.     

Galvanic corrosion between dental precious alloys and magnetic stainless steels used for dental magnetic attachments

In this study, we examined the corrosion behavior of dental precious alloys and magnetic stainless steels, namely SUS 444, SUS XM27, and SUS 447J1, used for dental magnetic attachments. Their galvanic corrosion behavior was evaluated from the viewpoint of corrosion potentials when they were in contact with each other. Rest potentials of the precious alloys were constantly higher than those of magnetic stainless steels. Since most gold alloys raised the corrosion potential more significantly than silver alloys did, silver alloys seemed to be better suited than gold alloys for combination with magnetic stainless steels. However, all corrosion potential values were sufficiently lower than the breakdown potentials of the stainless steels and existed within their passive regions. Based on the findings of this study, SUS XM27 and SUS 447J1--which exhibited higher breakdown potentials than SUS 444--emerged as the preferred choices for combination with gold alloys.     

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.     

Cu-Ti, Co-Ti and Ni-Ti systems: corrosion and microhardness

Titanium alloys of 10 wt%-72 wt% Cu, 10 wt%-80 wt% Co and 20 wt%-84 wt% Ni were investigated. Ingots were fabricated in a vacuum/argon tungsten arc furnace. The surfaces of the alloys were examined by optical microscopy and SEM/EDS, and the Knoop hardness values of the alloys were measured. The corrosion resistance of the alloys was determined by a potentiodynamic polarization technique in buffered Ringer's solution. When a threshold composition of 30 wt% alloy was reached, a large decrease in corrosion resistance was found to occur. Knoop hardness measurements showed that similar hardness values of approximately 300 KHN can be obtained in all systems with lower alloy content. These values are similar to those obtained with a commercial dental titanium alloy.     

Studies on Au-Ag-Pd-Cu alloys. (Part 1) Effects of Au component on some properties of alloys (author's transl)]

Au-Ag-Pd-Cu quaternary dental alloys were studied to find out the more favourable Au content. Pd and Cu content were fixed to 20 wt% respectively but Au content were changed from 10 wt% to 40 wt% and Ag content were balanced. Tensile, hardness, corrosion and castability test were carried out. Results were as follows. 1) The tensile strength and elongation of swaged specimen showed highest value at 30 wt% Au but in case of casted specimen, tensile strength was highest as 20 wt% and elongation was minimum at 30 wt% Au. Those differences between swaged and cast specimens were seemed to depend on the casting porosities. 2) The Vickers hardness test showed that the hardness gradually increased with Au content and showed the highest value at 30 wt% Au. 3) The corrosion test in the 0.1% Na2S solution indicated that the corrosion resistance was increased with Au content but the rate of increment was slow down at 30 wt% Au. 4) The castability test showed that no significant difference was found out one another. These experimental results seemed to indicate that 30 wt% Au was the favourable composition for Au-Ag-Pd-Cu dental alloys.