牙科用铬合金在不同pH值的人工唾液中耐腐蚀性能的研究

目的在模拟口腔环境下,研究牙科用铬合金（钴铬合金和镍铬合金）在pH值为7和5的人工唾液中的电化学腐蚀行为。方法用动电位极化曲线法,测定铬合金在pH值为7和5的人工唾液中自腐蚀电位、自腐蚀电流密度,与含钛元素镍铬合金进行比较分析;并用电化学阻抗谱研究铬合金的腐蚀机制和耐腐蚀性能。结果钴铬合金的自腐蚀电流密度低于含钛元素镍铬合金和镍铬合金,阻抗值高于含钛元素镍铬合金和镍铬合金;而镍铬合金自腐蚀电流密度高于含钛元素镍铬合金,阻抗值略低于含钛元素镍铬合金。随pH值下降,合金表面自腐蚀电流密度均升高,阻抗值均降低,但钴铬合金的变化幅度最小。结论钴铬合金的耐腐蚀性能优于镍铬合金和含钛元素镍铬合金;随pH值下降,合金耐腐蚀性能均发生不同程度的下降。     

3种牙科铸造金属模拟唾液浸泡后粗糙度的变化

目的：通过考察钴铬合金、镍铬合金以及纯钛在不同pH值人工唾液中浸泡后表面粗糙度的变化,研究3种常用牙科金属的耐腐蚀能力。方法：将3种金属的标准铸造试件逐级打磨抛光后。浸泡于pH值分别为7．0和5．6的人工唾液中。3个月后检测试件表面粗糙度,并用金相显微镜观察试件表面。采用SPSS11．0软件包对数据进行单因素方差分析及t检验。结果：pH=5．6的人工唾液浸泡后,3种材料表面粗糙度有显著差异,镍铬合金〉钴铬合金〉纯钛金属（P〈0．01）。pH=7．0的人工唾液浸泡后,镍铬合金表面粗糙度大于钴铬合金和纯钛（P〈0．01）,但钴铬合金和纯钛之间无统计学差异（p〉0．05）。pH=5．6人工唾液浸泡组的镍铬合金和钴铬合金表面粗糙度大于pH=7．0组的同种材料（P〈0．01）。各试验组表面粗糙度大小与显微镜观察到的材料表面腐蚀程度一致。结论：纯钛在酸性和中性环境下均有较强的耐腐蚀性,钴铬合金、镍铬合金在酸性介质中的耐腐蚀性较差。3种金属的耐腐蚀性由大到小排列为：纯钛金属〉钴铬合金〉镍铬合金。     

人工唾液中氯化钠浓度对钴铬、镍铬、含钛镍铬合金腐蚀行为的影响

目的：在人工唾液中氯化钠浓度升高的条件下,用电化学阻抗谱研究3种牙科常用合金（钴铬、镍铬、含钛镍铬合金）腐蚀行为的变化。方法：测定在人工唾液中氯化钠浓度分别为0.9%、2%、3%的条件下,3种合金的电化学阻抗谱,将各体系中合金界面电容和电荷转移电阻拟合,分析其腐蚀机制和耐腐蚀性能的变化。结果：随着氯化钠浓度升高,3种合金的界面电荷转移电阻（Rt值）都分别减小,界面电容（Qdl）增大,腐蚀反应过程加剧,抗蚀能力降低。但钴铬合金的Rt值是最大的。结论：在高氯环境中,3种合金腐蚀反应加快,抗腐蚀能力均降低,但钴铬合金抗腐蚀能力相对较强,这将影响它们的使用寿命。     

不同pH值与氟离子浓度对口腔常用金属修复材料电化学腐蚀的影响

目的 研究不同pH值与不同浓度氟离子(F-)对HBIC种植体和常用的四种冠修复金属材料在人工唾液中电化学腐蚀的影响.方法 将5种口腔常用金属,金合金(Au)、镍铬合金(NiCr)、钴铬合金(CoCr)、铸造纯钛(Ti)、HBIC种植钛材(H-Ti)分别置于不同pH值与含和不含F-的人工唾液中,采用动电位极化曲线法测得其自腐蚀电位和自腐蚀电流密度,分析材料的耐腐蚀性.结果 金合金、钴铬合金、镍铬合金的腐蚀电流密度随着H+的浓度增加而变大,差异有统计学意义(P<0.05),铸造纯钛及种植钛材在酸性含氟人工唾液中的腐蚀电流密度和自腐蚀电位变化明显,差异有统计学意义(P<0.05),F-对金合金的耐腐蚀性影响不明显.结论 pH的改变以及含氟环境会加剧种植体及其常用上部冠修复材料的电化学腐蚀性,金合金与纯钛的耐腐蚀性能较强.     

pH值对烤瓷工艺处理后的合金耐腐蚀性能的影响

目的研究不同pH值对经过烤瓷处理过的烤瓷合金的耐腐蚀性能的影响。方法制作金合金、纯钛、钴铬合金、镍铬合金试件,常规临床烤瓷,分别置于不同的pH值溶液中,应用电化学综合测试系统和腐蚀分析软件对受试合金行动电位极化扫描,绘制合金在人工唾液中的极化曲线,获得并分析材料的自腐蚀电位(Ecorr)和腐蚀电流密度(Icorr)。结果4种合金临床烤瓷加工后在同一pH值人工唾液中自腐蚀电位负值增加的排序为金合金、纯钛、钴铬合金、镍铬合金;4种合金在pH为5.6±0.04、pH=为.6±0.04人工唾液中均比pH为6.8±0.04中自腐蚀电流密度增大,自腐蚀电位负值增大。结论纯钛与金合金耐腐蚀性能好于钴铬合金,镍铬合金,随pH值下降,非贵金属耐腐蚀性能下降明显。     

铸造前纯钛和钴铬合金的耐腐蚀性研究

目的:探讨纯钛和新配方钴铬合金在体外的电化学腐蚀性.方法:应用Tafel曲线电化学腐蚀测量法,将纯钛合金和新配方钴铬合金浸泡在人工唾液和自来水中,温度室温,pH值为6.8,测量试件的腐蚀电位、腐蚀电流密度和极化电阻.应用扫描电镜(SEM)观察试件表面形态变化.结果:纯钛和钴铬合金在人工唾液和自来水中的腐蚀性均有显著差异(P<0.05),并且同种金属在人工唾液和自来水中的腐蚀性也存在显著差异(P<0.05).扫描电镜观察表明,纯钛金属表面的腐蚀痕迹比钴铬合金表面的腐蚀痕迹明显.结论:新配方钴铬合金比纯钛有较好的耐腐蚀性,而人工唾液比自来水对这两种金属的腐蚀性的影响更大.     

钴铬、镍铬、含钛镍铬烤瓷合金在人工唾液中耐腐蚀性能的比较

目的:评价钴铬、镍铬、含钛镍铬烤瓷合金在人工唾液中的耐腐蚀性能。方法:采用动电位极化曲线法测定钴铬、镍铬、含钛镍铬烤瓷合金试件的自腐蚀电流密度、极化电阻、自腐蚀电位,并得出3种合金的极化曲线。应用场发射扫描电子显微镜(FSEM),观察实验前、后试件表面的形貌变化。采用SPSS11.0软件包对数据进行单因素方差分析。结果:钴铬合金试件自腐蚀电流密度显著低于镍铬合金(P<0.05)及含钛镍铬合金(P<0.05);含钛镍铬合金试件自腐蚀电流密度低于镍铬合金(P<0.05)。钴铬合金试件的极化电阻显著高于镍铬合金(P<0.05)及含钛镍铬合金(P<0.05);含钛镍铬合金试件的极化电阻明显高于镍铬合金(P<0.05)。钴铬合金试件的自腐蚀电位高于镍铬合金(P<0.05)及含钛镍铬合金(P>0.05);含钛镍铬合金试件的自腐蚀电位高于镍铬合金(P>0.05)。FSEM显示,钴铬合金试样表面腐蚀较镍铬合金及含钛镍铬合金轻微。结论:钴铬烤瓷合金的耐腐蚀性优于镍铬烤瓷合金及含钛镍铬烤瓷合金,含钛镍铬烤瓷合金耐腐蚀性不及镍铬烤瓷合金。     

氯离子浓度对牙科铬合金耐腐蚀性能的影响

目的 在人工唾液中氯离子浓度升高的条件下,用动电位极化曲线法研究镍铬合金、钴铬合金和含钛镍铬合金的耐腐蚀性能的变化。方法 测定三种铬合金在氯化钠浓度分别为0.9%、2%、3%的人工唾液中的自腐蚀电位、自腐蚀电流密度,对其进行比较分析。结果 随着氯离子浓度升高,三种铬合金的自腐蚀电流密度均增大,腐蚀速度加快。钴铬合金受氯化钠浓度的影响最小。结论 在高氯环境中,三种铬合金腐蚀性能均降低,但钴铬合金耐腐蚀能力相对较强,这将影响它们的使用寿命。     

不同浓度茶多酚人工唾液溶液对牙科铸造合金腐蚀行为的影响

目的 研究镍铬合金、钴铬合金、纯钛在茶多酚人工唾液溶液中的电化学腐蚀行为.方法 将3种铸造合金分别浸泡在人工唾液以及浓度为1.25、2.50和5.00 g/L茶多酚人工唾液溶液中,采用动电位极化曲线法检测其自腐蚀电流密度(Icorr)、腐蚀电位(Ecorr)和极化电阻(Rp)等指标.结果 与人工唾液中Icorr相比、镍铬合金在1.25 g/L茶多酚人工唾液溶液中的Icorr显著增大(P < 0.01),且随着茶多酚浓度升高,Icorr逐渐减小、Rp逐渐增大.钴铬合金在4种溶液中的腐蚀速率明显不同(P < 0.01),在1.25 g/L茶多酚人工唾液溶液中的腐蚀速率显著小于在人工唾液中.纯钛在4种溶液中的腐蚀速度显著小于其他两种金属(P < 0.01).结论 有饮茶习惯的患者不宜选用镍铬合金制作修复体,而佩戴有钴铬合金或纯钛修复体的患者可适量饮茶,但无论哪类患者,都不建议饮浓茶.     

不同氟浓度的人工唾液对口腔常用金属腐蚀性的研究

目的:研究钻铬合金、纯钛及高钴铬钼合金在不同氟浓度的人工唾液中的电化学腐蚀行为.方法:将3种口腔常用金属分别在不同氟浓度(0%、0.05%、0.2%)的人工唾液中,采用动电位极化曲线法测得其腐蚀电位、腐蚀电流密度及极化电阻,分析材料的耐腐蚀性.结果:纯钛及钴铬合金的腐蚀电流密度随着氟的浓度增加而变大,极化电阻随着氟的浓...     

In vitro corrosion behavior of bioceramic, metallic, and bioceramic-metallic coated stainless steel dental implants.

OBJECTIVES: The most common metals and alloys used in dentistry may be exposed to a process of corrosion in vivo that make them cytotoxic. The biocompatibility of dental alloys is primarily related to their corrosion behavior. The aim of this work was to evaluate the corrosion behavior and thus the biocompatibility of the uncoated and coated stainless steels and compare the effect of type of coatings on corrosion behavior. METHODS: Three types of coatings, hydroxyapatite (HA), titanium (Ti), and a double-layer HA/Ti on AISI 316L stainless steel were made. HA coating was produced using plasma-spraying technique and Ti coating was made using physical vapor deposition process. In order to perform a novel double-layer composite coating, a top layer of HA was plasma-sprayed over a physical vapor deposited Ti layer on AISI 316L stainless steel. Structural characterization techniques including XRD, SEM and EDX were used to investigate the microstructure, morphology and crystallinity of the coatings. Electrochemical potentiodynamic tests were performed in physiological solutions in order to determine and compare the corrosion behavior of the coated and uncoated specimens as an indication of biocompatibility. RESULTS: Double-layer HA/Ti coating on AISI 316L SS had a positive effect on improvement of corrosion behavior. The decrease in corrosion current densities was significant for these coated specimens and was much lower than the values obtained for uncoated and single HA coated specimens. Ti coating on AISI 316L SS also has a beneficial effect on corrosion behavior. The results were compared with the results of corrosion behavior of HA coated commercially pure titanium (cpTi) and uncoated cpTi. SIGNIFICANCE: These results demonstrated that the double-layer HA/Ti coated 316L SS can be used as an endodontic implant and two goals including improvement of corrosion resistance and bone osteointegration can be obtained simultaneously.     

Studies of Ti alloys for dental castings

Casting of Ti has been recently investigated in dentistry. The purpose of this study was to examine the alloying effect on the cast Ti. Metallurgical structures, mechanical properties, and in vitro corrosion resistance were, therefore, studied for cast Ti and for four selected cast Ti alloys such as Ti-6AI-4V, Ti-15V, Ti-20Cu, and Ti-30Pd. A "Castmatic" dental casting machine was utilized, which involved argon-arc melting and subsequent argon/vacuum-pressurized casting. The photomicrographs revealed quite large grains in the cast structures. XRD analyses on cast Ti metals showed the quasi-equilibrium phases present. The strength of cast Ti could be significantly increased by alloying. Cross-sectional microhardness measurements of cast Ti alloys showed U-type hardness distribution due to the surface mold reaction. All the cast Ti alloys examined showed a strong passivity trend in the corrosion test. The present results suggest that cast Ti alloys have promising features for future dental uses.     

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.     

细菌作用时间对不同蛋白质修饰的镍铬合金腐蚀性的影响

目的 探讨镍铬合金表面蛋白膜对合金抗微生物腐蚀能力的影响。方法 镍铬合金试件分别用纯人工唾液（AS）（设为对照组）、含1%小牛血清蛋白的人工唾液（BSA）和含0.22%溶菌酶的人工唾液（LSZ）（分别为实验组）进行浸泡处理,再置于变形链球菌菌液中分别培养12、24、36、48 h后取出,检测电化学阻抗谱（EIS）及动态极化曲线（POT）,了解镍铬合金表面腐蚀特性。采用SPSS17.0软件包对数据进行统计学分析。结果 电化学阻抗谱显示,12 h时,实验组抗腐蚀性能强于对照组,且LSZ组强于BSA组（P＜0.05）;24 h时,实验组间无显著差异（P＞0.05）,但强于对照组（P＜0.05）;36 h时,LSZ组抗腐蚀性能最弱,AS组与BSA组无显著性差异（P＞0.05）;48 h时,对照组抗腐蚀性能强于实验组,且LSZ组强于BSA组（P＜0.05）。动态极化曲线结果与电化学阻抗谱基本一致。结论 当镍铬合金表面黏附有BSA或LSZ时,早期可有效抑制变形链球菌的腐蚀作用,且LSZ有更好的抑制效果。随着细菌的持续作用,当表面蛋白膜被逐渐消耗后,镍铬合金对抗变形链球菌的腐蚀能力则会较未经蛋白膜黏附的试件更弱,即合金表面在蛋白膜被去除后较初始状态抗微生物腐蚀性能有所下降,且BSA的作用更明显。     

Study of the corrosion behavior of titanium and some of its alloys for biomedical and dental implant applications

The influence of alloying elements and the potential on the corrosion resistance of Ti and other Ti-based biomedical implant alloys under simulated physiological conditions is presented. Ti and its following alloys: Ti10Mo, Ti10Mo10Al, Ti7Al4.5V and Ti5Al4.5V and Ti5Al2.5Fe were studied. Electrochemical impedance spectroscopy was used and the experimental results were compared with those obtained by potentiostatic and potentiodynamic techniques. All the measurements were made in Ringer’s solution at pH 7.8 and at different potentials (E_corr, ?650, ?500, 0, +200 and +400 mV vs. SCE). Under these conditions, all the Ti-based alloys exhibited spontaneous passivity. It was evident that Mo, V and Fe improved passivity and limited the active corrosion of the β-phase of Ti while Al enrichment of the α-phase was found to be detrimental to the passivity and corrosion resistance of Ti.     

An electrochemical investigation of TMJ implant metal alloys in an artificial joint fluid environment: The influence of pH variation

ObjectiveTo investigate the corrosion behaviour of commonly used TMJ implants alloys (CoCrMo and Ti6Al4V) under simulated physiological conditions.MethodsCorrosion behaviour was evaluated using standard electrochemical corrosion techniques and galvanic corrosion techniques as per ASTM standards. Standard electrochemical tests (E_corr, I_corr, R_p and C_f) were conducted in bovine calf serum (BCS), as a function of alloys type and different pHs. Galvanic corrosion tests were conducted in BCS at a pH of 7.6. Alloy surfaces were characterized using white-light interferometry (WLI) and scanning electron microscopy (SEM).ResultsThe potentiodynamic test results exhibited the enhanced passive layer growth and a better corrosion resistance of Ti6Al4V compared to CoCrMo. Electrochemical impedance spectroscopy measurements demonstrated the influence of protein as a function of pH on corrosion mechanisms/kinetics. Galvanic coupling was not a major contributor to corrosion. SEM and WLI images demonstrated a significantly higher in surface roughness in CoCrMo after corrosion.ConclusionsThe results of this study suggest that Ti6Al4V shows superior corrosion behaviour to CoCrMo due to its strong passive layer, simulated joint fluid components can affect the electrochemical nature of the metal/electrolyte interface as a function of pH, and the galvanic effect of coupling CoCrMo and Ti6Al4V in a single joint is weak.     

Structure, castability and mechanical properties of commercially pure and alloyed titanium cast in graphite mould

This report is a study of structure, castability, mechanical properties as well as corrosion behaviour of titanium doped with up to 5 weight percentage (wt%) of a series of alloy elements, including Ta, Mo, Nb, Hf, Zr, Sn, Bi and Ag. The results indicate that, with addition of 1 wt% alloy element, Bi and Mo were most effective in enhancing the castability of titanium. With more alloy elements added, the castability values of most alloys more or less decreased. Except Ti-Mo system, all Ti alloys with a fine acicular morphology had the same crystal structure (hcp) as that of c.p. Ti with a typical lath type morphology. When 3 wt% or more Mo was added, a finer orthorhombic alpha' phase was formed. The microhardness and bending strength values of Ti alloys were all higher than those of c.p. Ti. Among all alloys, Ti-Mo system exhibited the highest hardness and strength level. For a certain alloy, the bending strength did not necessarily increase with its alloy content. Except Ti-5Zr and Ti-Mo alloys, the bending moduli of most alloy systems were not much different from that of c.p. Ti. All alloys showed an excellent resistance to corrosion in Hanks' solution at 37 degrees C.     

Evaluation of anodic behavior of commercially pure titanium in tungsten inert gas and laser welds

Purpose: This study evaluated the resistance to corrosion in welds made with Tungsten Inert Gas (TIG) in specimens made of commercially pure titanium (cp Ti) in comparison with laser welds. Materials and Methods: A total of 15 circular specimens (10‐mm diameter, 2‐mm thick) were fabricated and divided into two groups: control group—cp Ti specimens (n = 5); experimental group—cp Ti specimens welded with TIG (n = 5) and with laser (n = 5). They were polished mechanically, washed with isopropyl alcohol, and dried with a drier. In the anodic potentiodynamic polarization assay, measurements were taken using a potentiostat/galvanostat in addition to CorrWare software for data acquisition and CorrView for data visualization and treatment. Three curves were made for each working electrode. Corrosion potential values were statistically analyzed by the Student's t‐test. Results: Statistical analysis showed that corrosion potentials and passive current densities of specimens welded with TIG are similar to those of the control group, and had lower values than laser welding. TIG welding provided higher resistance to corrosion than laser welding. Conclusion: Control specimens welded with TIG were more resistant to local corrosion initiation and propagation than those with laser welding, indicating a higher rate of formation and growth of passive film thickness on the surfaces of these alloys than on specimens welded with laser, making it more difficult for corrosion to occur.