Corrosion resistance of a passivated and non-passivated cobalt-chromium alloy

The release of cobalt and chromium from a passivated and non-passivated cobalt-chromium alloy in artificial saliva has been measured using nuclear tracer technique. The corrosion resistance of the passivated specimens was improved by a factor of about four compared to the non-passivated specimens with regard to the initial cobalt release. The specimens were exposed to the saline solutions for periods up to about 8 wk. The cobalt release is associated mainly with electrochemical corrosion processes, since particulate matter retained on a filter was only registered to a minor extent. It is suggested that the decrease in release of cobalt and chromium after passivation is connected to the formation of Cr-O and/or Cr-OH bonds in the protective film which impede the movement of cobalt and chromium from the alloy into the saliva.     

空气环境对多次铸造的钴铬合金机械性能的影响

目的 :探讨空气环境对多次铸造的钴铬合金机械性能的影响。方法 :检测各代试样的抗拉强度、伸长率、硬度等机械性能指标 ,比较相应的金相学检查 ,气孔及非金属性夹杂物分析 ,化学成分分析。结果 :空气三代的伸长率与空气一代的相比有显著差异。结论 :在空气环境中熔铸的钴铬合金 ,在每次不加入新合金的前提下 ,只能用至第二代 ,否则将影响修复体的质量。     

Dental implant suprastructures using cobalt-chromium alloy compared with gold alloy framework veneered with ceramic or acrylic resin: a retrospective cohort study up to 18 years

Background: An association between the long‐term success and survival of implant‐supported prostheses as a function of biomaterial combinations has not been established. The use of cast cobalt–chromium for the suprastructure framework may be an alternative to the conventional approach of using type 3 gold alloys. Materials and methods: A retrospective chart audit of all patients who had received implant‐supported fixed dental prostheses (FDP) before 1996 was identified in a private practice clinic. Data were recorded for FDPs made from four combinations of alloy frameworks and veneering material, i.e. type 3 gold and cobalt–chromium with ceramic or prefabricated acrylic teeth. The extracted data from the charts were subjected to explorative statistical tests including Kaplan–Meier survival analyses. Results: Patients (n=198) with 270 short and extensive FDPs supported entirely by 1117 implants were identified. The average follow‐up observation periods varied between 4 and 220 months, with an average of 120 months. The success and survival, as well as event rates and types of biological and technical complications, were similar for implant‐supported FDPs using cobalt–chromium and type 3 gold alloy frameworks veneered with ceramics or prefabricated acrylic teeth. An influence of the suprastructure biomaterial combination on the clinical performance of the individual supporting implants could not be established. Conclusions: Implant‐supported FDPs made from type 3 gold or cobalt–chromium frameworks and veneered with ceramic or prefabricated acrylic teeth demonstrate comparable clinical performance. The biomaterial combinations do not appear to influence the success or survival of the individual implants. To cite this article:
Teigen K, Jokstad A. Dental implant suprastructures using cobalt–chromium alloy compared with gold alloy framework veneered with ceramic or acrylic resin: a retrospective cohort study up to 18 years.
Clin. Oral Impl. Res. 23 , 2012; 853–860.
doi: 10.1111/j.1600‐0501.2011.02211.x     

镍铬和含钛镍铬烤瓷合金的耐腐蚀性能研究

目的 评价2种镍铬和1种含钛镍铬烤瓷合金试件在人工唾液中的耐腐蚀性能.方法 采用电化学极化曲线法测定2种镍铬和1种含钛镍铬烤瓷合金试件的自腐蚀电流密度(Icorr)、极化电阻(Rp)、自腐蚀电位(Ecorr),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形貌变化,并对数据进行单因素方差分析.结果 Bellabond镍铬烤瓷合金的Icorr低于Neotitan含钛镍铬烤瓷合金(P<0.05)及粤海镍铬烤瓷合金(P>0.05):粤海镍铬烤瓷合金Icorr低于Neotitan含钛镍铬烤瓷合金(P>0.05).Bellabond镍铬烤瓷合金的Rp明显高于粤海镍铬烤瓷合金(P<0.05)及Neotitan含钛镍铬烤瓷合金(P<0.05);粤海镍铬烤瓷合金试件的Rp高于Neotitan含钛镍铬烤瓷合金(P>0.05).Bellabond镍铬烤瓷合金的Ecorr低于粤海镍铬烤瓷合金(P>0.05)及Neotitan含钛镍铬烤瓷合金(P>0.05):Neotitan含钛镍铬烤瓷合金的Ecorr高于粤海镍铬烤瓷合金(P>0.05).FSEM显示,Bellabond镍铬烤瓷合金表面腐蚀较粤海镍铬烤瓷合金和Neotitan含钛镍铬烤瓷合金轻微.结论 Bellabond镍铬烤瓷合金的耐腐蚀性较粤海镍铬烤瓷合金和Neotitan含钛镍铬烤瓷合金优良,Neotitan含钛镍铬烤瓷合金耐腐蚀性与粤海镍铬烤瓷合金无明显差异.     

Cytotoxic effects of cobalt-chromium alloys on fibroblasts derived from human gingiva

Abstract – The in vitro toxicity of 15 different cobalt-chromium alloys used in removable partial dentures and dental implants was studied. The composition of the alloys was determined by X-ray spectrometry. Alloys were tested on human oral fibroblasts in low density, semiconfluent or confluent cultures. The cultures were observed in a phase contrast microscope over a period of 3 wk. The alloys could be divided into three groups depending upon the degree of cell injury evoked. Group I alloys caused no cell injury. Group II alloys caused slight to moderate cell injury seen first after 3–7 days of exposure. Group III alloys caused severe cell injury with signs of cell damage detected after 12 h and total ceil death after 3–14 days. The alloys' composition varied considerably with regard to cobalt, chromium and nickel as well as other components. Nevertheless, group II and III alloys had a higher nickel content than group I alloys in general.     

Corrosion resistance of cobalt-chromium and palladium-silver alloys used in fixed prosthetic restorations

The corrosion resistance of a cobalt-chromium (Co-Cr) alloy was assessed with a view to determining its potential use in the manufacture of fixed dental prostheses. The electrochemical behaviour of the alloy was compared with that of two palladium (Pd)-based alloys. Measurements of corrosion potential and anodic polarization were performed on the alloys, and the specimen surfaces were examined by using scanning electron microscopy. Although the corrosion potential of the Co-Cr alloy was lower than that of the Pd-based alloys, the corrosion currents and polarization resistance values were similar for all three alloys. All materials showed a very high resistance to corrosion. Given that the beneficial mechanical properties of Co-Cr alloys have already been established, this type of alloy may be a suitable alternative for use in the manufacture of fixed dental prostheses.     

齿科钴铬-镍铬合金激光焊接后耐腐蚀性评价

目的:研究激光焊接钴铬-镍铬合金的体外电化学行为及离子释出情况。方法:在体外模拟口腔环境中,测出激光焊接钴铬-镍铬合金阳极极化曲线及特征指数;检测激光焊接镍铬-钴铬合金在不同时间的离子释出情况,以钴铬合金、镍铬合金为对照。结果:钴铬合金自腐蚀电位低于镍铬合金,激光焊接钴铬-镍铬合金的自腐蚀电位、维钝电流密度、破裂电位介于前两者之间;激光焊接镍铬-钴铬合金,镍离子释出量7日后少于镍铬合金,钴离子释出量始终高于镍铬合金。结论:激光焊接钴铬-镍铬合金后,钴铬合金的阳极保护作用可减少镍铬合金镍离子释出,有助于改善镍铬合金生物相容性;激光焊接钴铬-镍铬合金,对其整体耐腐蚀性未有较大影响。     

钴铬合金可摘局部义齿残余应力的测定与消除

目的 研究钴铬合金可摘局部义齿残余应力的测定和消除方法 。方法 设计出圆形试件模拟铸造支架,对其进行残余应力的测试,用自然时效和热处理时效对试件进行处理。结果 自然时效和热处理时效可有效降低试件的残余应力值。结论 增加热处理时效以解决残余应力。     

激光焊接铁铬钼合金与钴铬合金的机械性能

目的：测试激光焊接铁铬钼软磁合金与钴铬合金的机械性能，为临床应用提供参考。方法：采用国产Nd：YANG程控激光焊接机焊接铁铬钼软磁合金与钴铬合金，以激光焊接钴铬合金作为对照。利用Instron万能拉仲实验机测试焊接后的拉仲强度、0．2％屈服强度，作断裂口的扫描电镜分析，并分别进行比较。结果：激光焊接铁铬钼软磁合金与钴铬合金的拉伸强度、0．2％屈服强度与对照组无差别。激光焊接铁铬钼合金与钴铬合金的断裂口呈韧性—解理混合型断裂，而激光焊接钴铬合金的断口呈准解理断裂。结论：激光焊接铁铬钼软磁合金与钴铬合金的机械性能可满足临床需要。     

钴铬合金烤瓷髓腔固位冠不同厚度内冠适合性的比较研究

目的:探讨钴铬合金烤瓷髓腔固位冠内冠厚度对适合性的影响.方法:以磨牙平均解剖数据为基础,建立材料学研究简化模型,制作钴铬合金烤瓷髓腔固位冠内冠,厚度分别为0.3mm、0.5mm、0.8mm、1.0mm,每组8个试件,共32个.采用硅橡胶印模复制法,在体视显微镜下测量边缘间隙、轴角间隙、轴壁1间隙、轴壁2间隙、底部间隙处硅橡胶印模的厚度值,对不同厚度内冠的适合性进行方差分析及多重LSD比较.结果:冠边缘处间隙薄膜厚度值为62.14-68.27μm,轴角部位为61.50-69.33μm,轴壁为31.31-44.25μm,髓腔固位形底部为56.02-67.96μm.经方差分析,在各测量位点,不同厚度的内冠之间适合性无显著性差异.结论:4种不同厚度内冠的钴铬合金烤瓷髓腔固位冠,其内部和边缘适合性均达到临床要求.在胎龈距离不足的情况下采用0.3mm厚度的内冠对钴铬合金烤瓷髓腔固位冠边缘适合性无明显影响.     

多孔TiNi合金牙种植材料的制备及性能检测

目的 制备多孔TiNi合金牙种植材料,为该合金进一步进行动物实验及临床应用提供实验依据.方法 采用添加氢化钛和碳酸氢铵做为造孔剂,模压成型(200 MPa),真空烧结.对烧结后的试样进行XRD物相分析、显微观测以及能谱分析.结果 XRD物相分析表明,Ti-Ni合金试样中主要有TiNi、Ti2Ni、TiNi3三相.在烧结工艺相同的情况下,钛含量不同的试样孔隙的数量、大小、均匀程度都相差不多.结论 TiNi合金种植体制备成三维多孔结构是可行的.     

高金合金与镍铬合金烤瓷冠临床应用效果的比较

目的：探讨和比较高金合金、含钛的镍铬合金（Tilite、钛莱特）、镍铬合金烤瓷冠的临床应用效果。方法：分别制作高金合金、钛莱特、镍铬合金烤瓷冠各60个，共180个。在烤瓷冠完成时和复查时，临床检查冠的颜色、颈缘染色、边缘密合度和牙折断、折裂情况，观察3年。结果：钛莱特和镍铬合金烤瓷冠在颜色、颈缘染色、边缘密合度方面无显性差异（P＞0.05）；高金合金烤瓷冠没有颈缘染色，在颜色和边缘密合度方面优于Tilite和镍铬合金烤瓷冠（P＜0.05）；3组都未见牙折断、折裂及组织过敏反应。结论：高金合金烤瓷冠比镍铬合金烤瓷冠有更好的临床效果。     

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-75合金在口腔修复应用的腐蚀性

为评价Ti－75合金在口腔修复应用的耐腐蚀性，用动电位极化技术测试了五种材料在人工唾液中的腐蚀性。结果显示Ti-75合金自腐蚀电位介于TA2和TC4之间，破裂电位高于CO－Cr、Ni－Cr合金；Ti－75测试面未见腐蚀，而Co－Cr、Ni－Cr合金均有全面腐蚀和点蚀；结合极化曲线整体形态分析，结论：Ti－75合金的耐蚀性与TA2、TC4相似，但优于临床现用的Co－Cr、Ni－Cr合金。     

In vitro evaluation of the bonding of auto-polymerizing soft denture liner to cobalt-chromium alloy

This study evaluated the effects of surface pre-treatments on the bonding of auto-polymerizing silicone soft denture liner to a Co-Cr alloy denture base after cyclic thermal stressing. The bonding surfaces of Co-Cr alloy cylinders (8 mm diameter and 4 mm high) were polished with a 600-grit silicon carbide paper. The bonding surfaces received one of three pre-treatments, which included either the application of a metal primer, a metal primer after air abrasion, or a resin primer after adhesive resin coating. Tensile specimens were fabricated by polymerizing a 2-mm thickness of soft denture liner between a pair of pre-treated denture base cylinders. Failure loads were measured by tensile testing after subjecting the specimen to 0, 5, 10, 20, and 30 thousand thermal cycles. Seven specimens were fabricated for 15 groups, including three pre-treatments and five thermal cycle groups. Failure loads of resin-bonded specimens, which were formerly reported, were used as references. All data were statistically analysed by two-way anova and Bonferroni test at the 95% confidence level. Adhesive resin coating of the metal surface was effective in enhancing the failure loads up to 5000 thermal cycles. However, failure loads of all metal-bonded groups were significantly lower than those of resin-bonded groups at all thermal cycling intervals. The results of this in vitro study implied that polymerizing adhesive resin on the Co-Cr alloy might be a promising method, when the clinicians need to acquire improved bonding of an auto-polymerizing soft denture liner to Co-Cr alloy denture bases.     

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。     

不同比例的新旧钴铬合金机械性能的研究

通过比较不同比例的新旧钴铬合金铸造后的抗拉强度,屈服强度,延伸率,硬度等机构性能指标,并结合相应的金相观察及化学成份分析,得出结论;铸造钴铬合金中可加入不超过４０％的仅铸造过一次的旧料而不影响合金的主要机械性能,超过这一比例,将影响修复体的质量。     

两种表面改性方法对钴-铬合金化学腐蚀行为的影响

目的研究钴-铬合金表面镀氮化钛薄膜和镀金薄膜后对其化学腐蚀行为的影响。方法利用多弧离子镀和电镀方法分别在钴-铬合金表面沉积氮化钛和金薄膜,将两种镀膜和未镀膜试件分别浸入人工唾液,在37℃恒温下浸泡,在第30、60、90天定量取浸泡的人工唾液10 ml,采用原子吸收光谱法测定唾液中的钴离子含量,浸泡结束后,检测试件的重量变化。结果在3个时间点,镀氮化钛试件释出的钴离子量都显著小于镀金和未镀膜组,镀氮化钛组和未镀膜组试件浸泡前后的失重量显著小于镀金组。结论在钴-铬合金表面镀氮化钛膜可显著减少金属离子释出,提高其耐腐蚀性能,效果可靠,优于镀金。     

激光表面强化技术对牙用铸造合金耐腐蚀性能影响的研究

目的研究激光表面强化技术对牙用铸造合金耐腐蚀性能的影响。方法制备23个钴铬合金金属片试件,将其中22个试件随机分成实验组（试件进行激光表面强化处理）和对照组（试件不进行激光处理）,每组11个,其中10个用电化学方法检测耐腐蚀性能,1个用扫描电镜观察表面金相结构及形貌。另取1个试件,其表面只进行部分区域激光表面强化处理,用于表面金相结构及形貌的对比观察。结果实验组试件金属晶粒分布均匀,而且晶粒细化,尺寸基本一致;部分区域激光表面强化处理试件的激光强化处理区有明显细化晶粒的现象。实验组和对照组自腐蚀电位、自腐蚀电流对数间的差异有统计学意义（P<0.01）。结论激光表面强化处理可以明显提高钴铬合金在人工唾液中的耐腐蚀性能。     

Effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of glass ceramic fused to gold or cobalt-chromium alloy

Purpose: To evaluate the effect of airborne‐particle abrasion and mechanico‐thermal cycling on the flexural strength of a ceramic fused to cobalt–chromium alloy or gold alloy. Materials and Methods: Metallic bars (n = 120) were made (25 mm × 3 mm × 0.5 mm): 60 with gold alloy and 60 with Co–Cr. At the central area of the bars (8 mm × 3 mm), a layer of opaque ceramic and then two layers of glass ceramic (Vita VM13, Vita Zahnfabrick) were fired onto it (thickness: 1 mm). Ten specimens from each alloy group were randomly allocated to a surface treatment [(tungsten bur or air‐particle abrasion (APA) with Al₂O₃ at 10 mm or 20 mm away)] and mechanico‐thermal cycling (no cycling or mechanically loaded 20,000 cycles; 10 N distilled water at 37°C and then thermocycled 3000 cycles; 5°C to 55°C, dwell time 30 seconds) combination. Those specimens that did not undergo mechanico‐thermal cycling were stored in water (37°C) for 24 hours. Bond strength was measured using a three‐point bend test, according to ISO 9693. After the flexural strength test, failure types were noted. The data were analyzed using three factor‐ANOVA and Tukey's test (α= 0.05). Results: There were no significant differences between the flexural bond strength of gold and Co–Cr groups (42.64 ± 8.25 and 43.39 ± 10.89 MPa, respectively). APA 10 and 20 mm away surface treatment (45.86 ± 9.31 and 46.38 ± 8.89 MPa, respectively) had similar mean flexural strength values, and both had significantly higher bond strength than tungsten bur treatment (36.81 ± 7.60 MPa). Mechanico‐thermal cycling decreased the mean flexural strength values significantly for all six alloy‐surface treatment combinations tested when compared to the control groups. The failure type was adhesive in the metal/ceramic interface for specimens surface treated only with the tungsten bur, and mixed for specimens surface treated with APA 10 and 20 mm. Conclusions: Considering the levels adopted in this study, the alloy did not affect the bond strength; APA with Al₂O₃ at 10 and 20 mm improved the flexural bond strength between ceramics and alloys used, and the mechanico‐thermal cycling of metal‐ceramic specimens resulted in a decrease of bond strength.