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.     

种植体材料钛与种植体上部结构合金间电偶腐蚀性能的研究

目的评价TA2型商业纯钛分别与金合金、钴铬合金、钛合金及镍铬合金在体外的电偶腐蚀行为。方法在人工唾液中体外模拟TA2型商业纯钛分别与金合金、钴铬合金、钛合金及镍铬合金接触时的回路,测量其15 h的混合电位和电偶电流值并描绘电流时间曲线。结果四组合金接触8 h后电流达到稳定,稳定后电偶电流值排列顺序为Ti/Au相似文献   

种植体材料钛与种植体上部结构合金问电偶腐蚀性能的研究

目的 评价TA2型商业纯钛分别与金合金、钴铬合金、钛合金及镍铬合金在体外的电偶腐蚀行为.方法 在人工唾液中体外模拟TA2型商业纯钛分别与金合金、钴铬合金、钛合金及镍铬合金接触时的回路,测量其15 h的混合电位和电偶电流值并描绘电流时间曲线.结果 四组合金接触8 h后电流达到稳定,稳定后电偶电流值排列顺序为Ti/Au相似文献   

牙用镍铬合金表面不同涂层电化学腐蚀研究

目的:通过电化学腐蚀法测试镍铬合金表面不同涂层在中性及酸性环境中的抗腐蚀性能.方法:分别以中性和酸性人工唾液为电解液,测量不同涂层的镍铬合金试件电极的自然腐蚀电位Ecorr、极化电阻Rp.结果:在中性和酸性人工唾液中,无论镀膜与否的镍铬合金的自腐蚀电位(Ecorr)均为正值,不易发生电化学腐蚀和电偶腐蚀.结论:氮化钛膜、电镀金膜、金泥涂层及金瓷涂层的镍铬合金具有较强抗腐蚀性和美观性,可提高基体金属的耐腐蚀性能.     

软磁合金与4 种齿科合金间电偶腐蚀的浸泡实验研究

目的:评价铁铬钼软磁合金与4种口腔常用合金在模拟口腔环境中的电偶腐蚀性能。方法:Fe-16Cr-2Mo软磁合金分别与钛75合金、TA2型纯钛、Co-Cr合金、Ni-Cr烤瓷合金组成的4组电偶对在人工唾液中浸泡6个月后,以原子吸收光谱仪测定每组电偶对浸泡液中溶出的金属离子浓度。结果:4组电偶对中析出的离子量与对照组相比均无显著差异(P>0.05)。结论:铁铬钼软磁合金在口腔环境中与牙科常用合金间可以认为不会有电偶腐蚀发生。     

Ti-6Al-7Nb合金与口腔常用合金间电偶腐蚀的研究

目的:评价Ti-6Al-7Nb合金与3种口腔常用合金在人工唾液中的电偶腐蚀性.方法:运用电化学方法测量Ti-6Al-7Nb合金与纯钛(TA2型)、Ni-Cr烤瓷合金、Co-Cr合金4种金属材料在人工唾液中的自腐蚀电位(Ecorr)塔菲尔曲线,并测量Ti-6Al-7Nb合金与其他3种金属组成电偶对后的电偶电流密度值,分析Ti-6Al-7Nb合金与不同金属偶合后的耐电偶腐蚀能力.结果:Ti-6Al-7Nb合金、TA2、Co-Cr合金和Ni-Cr烤瓷合金的Ecorr值(mV)分别为-111.8±0.02、-156.6±0.03、-246.2±-0.07和-298±0.08,两两比较均有显著性差异(P＜0.01);Ti-6Al-7Nb合金与TA2、Co-Cr合金和Ni-Cr烤瓷合金组成电偶对后测得的电偶电流密度值(μA/cm2)分别为0.46±0.21、1.37±0.90和2.25±1.52,两两比较均有显著性差异(P＜0.01).结论:Ti-6Al-7Nb合金在人工唾液环境中具有良好的耐腐蚀性能,与牙科常用合金偶合后不会有电偶腐蚀发生.     

口腔修复常用合金稳态电位的测定

目的 评价口腔修复常用合金的稳态电位及其发生腐蚀的倾向。方法 测量五种修复常用合金在人工唾液中的初浸电位及24h后的稳态电位，并作统计学分析。结果 得出五种材料的电偶序为：金合金、纯钛、钴铬合金、无锌银汞、含锌银汞。浸泡24h前后，金合金、纯钛、钴铬合金均为正移，而无锌银汞则负向移动。无锌银汞和含锌银汞的电位有显著性差异（P〈0．05）。结论 金合金、纯钛、钴铬合金是耐腐蚀性较好的材料。无法避免不同金属的同时应用时，应尽量选择电偶序中相邻的两种金属。建议临床使用无锌银汞代替含锌银汞。     

含氟环境对烤瓷金属耐腐蚀性能的影响

目的：研究分析氟离子环境对经烤瓷工序处理后金属耐腐蚀性能的影响。方法：制作金（Au）合金、纯钛（Ti）、钴铬（CoCr）合金、镍铬（NiCr）合金试件各6件,模拟临床烤瓷处理后分别置于人工唾液（A组）,含有0.2% NaF的人工唾液中（B组）,绘制极化曲线,获得并分析材料的自腐蚀电位和腐蚀电流密度。结果：B组与A组比较,镍铬合金、钴铬合金、纯钛自腐蚀电位负值增大,差异有统计学意义（P〈0.05）,金合金无差异。同种金属B组与A组相比腐蚀电流密度增加,差异有统计学意义（P〈0.05）。结论：氟离子环境能使得烤瓷处理过金属的耐腐蚀性能下降,腐蚀速度加快。金合金与纯钛耐腐蚀性能较强,其次是CoCr合金,NiCr合金最差。     

3种合金在不同pH值人工唾液中电化学腐蚀的研究

目的 研究表面镀金的镍铬合金在不同pH值人工唾液中的腐蚀行为,并将其与镍铬合金、金合金相比较.方法 采用动电位极化曲线法,比较镍铬合金镀金后在pH5.0和6.8的人工唾液中的自腐蚀电位(EaXT)、自腐蚀电流密度(IaXT)和极化电阻(Rp).应用场发射扫描电子显微镜(FSEM)观察试件实验前、后形貌的变化.结果 镍铬合金、镀金镍铬合金和金合金试件在pH5.0和6.8的人工唾液中相比较,pH5.0时IaXT增大、Rp减小.FSEM显示镍铬合金镀金表面腐蚀在pH5.0和6.8的人工唾液中相比较,酸性人工唾液中腐蚀范围增大,但仍散在分布.结论 镍铬合金、镀金镍铬合金和金合金在酸性人工唾液中较中性人工唾液中耐腐蚀性能下降.     

牙用镍铬合金表面不同涂层抗腐蚀性研究

目的：探讨镍铬合金表面不同涂镀层的抗腐蚀性能。方法：将4种涂镀层镍铬合金试件，分别浸泡在中性人工唾液2个月、酸性人工唾液20d。结果：在中性和酸性人工唾液中，镍铬合金表面涂镀的氮化钛膜、电镀金膜、金泥涂层及金瓷涂层，都表现出良好的耐腐蚀性能。结论：在相同的人工唾液环境中，不含铍镍铬合金比含铍镍铬合金具有更佳的耐腐蚀性能。     

前牙金沉积烤瓷冠修复临床效果观察

目的探讨金沉积烤瓷冠的临床应用效果。方法临床选择行前牙烤瓷修复的患者96例(共120颗),随机分为3组:金沉积烤瓷冠组、铸造镍铬合金组、铸造金铂合金烤瓷冠组,每组各制作40例。30个月后临床复查,检查临床边缘密合度、颜色、牙龈炎性反应、烤瓷冠的折裂及崩瓷情况。结果金沉积烤瓷冠与金铂合金烤瓷冠边缘密合度接近,均优于镍铬合金烤瓷冠(P<0.05);金沉积烤瓷冠与金铂合金烤瓷冠的颜色均优于镍铬合金烤瓷冠(P<0.05);三者在崩瓷、折裂方面无差异。结论金沉积烤瓷冠具有良好的美观效果,边缘密合度好,抗折强度高。     

Galvanic coupling of steel and gold alloy lingual brackets with orthodontic wires: Is corrosion a concern?

Objectives:The aim of this research was to assess galvanic behavior of lingual orthodontic brackets coupled with representative types of orthodontic wires.Materials and Methods:Three types of lingual brackets: Incognito (INC), In-Ovation L (IOV), and STb (STB) were combined with a stainless steel (SS) and a nickel-titanium (NiTi) orthodontic archwire. All materials were initially investigated by scanning electron microscopy / x-ray energy dispersive spectroscopy (SEM/EDX) while wires were also tested by x-ray diffraction spectroscopy (XRD). All bracket-wire combinations were immersed in acidic 0.1M NaCl 0.1M lactic acid and neutral NaF 0.3% (wt) electrolyte, and the potential differences were continuously recorded for 48 hours.Results:The SEM/EDX analysis revealed that INC is a single-unit bracket made of a high gold (Au) alloy while IOV and STB are two-piece appliances in which the base and wing are made of SS alloys. The SS wire demonstrated austenite and martensite iron phase, while NiTi wire illustrated an intense austenite crystallographic structure with limited martensite. All bracket wire combinations showed potential differences below the threshold of galvanic corrosion (200 mV) except for INC and STB coupled with NiTi wire in NaF media.Conclusions:The electrochemical results indicate that all brackets tested demonstrated galvanic compatibility with SS wire, but fluoride treatment should be used cautiously with NiTi wires coupled with Au and SS brackets.     

pH值对口腔修复常用合金间瞬间电偶电流的影响

目的:研究不同pH值对口腔修复常用合金间瞬间电偶电流的影响。方法:在3种pH值人工唾液中体外模拟异种合金瞬间咬合接触时的回路,浸泡初记录各偶对的电位及15个瞬间接触电流值。结果:金合金与纯钛在3种pH值中偶合所测得的电流与其他偶对差别均有统计学意义(P<0.05);金合金与无锌银汞、含锌银汞偶合产生的电流,仅次于金合金与纯钛偶合产生的电流;纯钛与无锌银汞、含锌与无锌银汞产生的电流也较大;纯钛与含锌银汞在3种pH值的溶液中产生电流最低、与其他偶对差别均有统计学意义(P<0.05)。结论:金合金与纯钛偶合,在3种pH值的溶液中产生电流均为最大,临床上危害最大;金合金与无锌、含锌银汞偶合,纯钛与无锌银汞、含锌与无锌银汞产生的电流也较大,临床慎用。纯钛与含锌银汞在3种pH值溶液中产生电流均处于最低,临床可共存应用。     

软磁合金与口腔常用合金间电偶腐蚀的研究

目的：评价铁铬钼软磁合金与4种口腔常用合金在模拟口腔环境中的电偶腐蚀性能。方法：运用电化学方法测量软磁合金与钻75合金，纯钻TA2型，Ni-Cr烤瓷合金，Co—Cr合金组成电偶对后的自腐蚀电位(Ecorr)，阳极极化曲线，电偶电流密度，分析软磁合金与不同金属偶接后的耐腐蚀能力。结果：5种合金材料的Ecorr值均相差显著(P＜0．05)；电偶电流密度各组间有显著差异(P＜0．05)，电流密度值均极小。结论：铁铬钼软磁合金在口腔环境中与牙科常用合金问可以认为不会有电偶腐蚀发生。     

口腔内3种合金共存下的离子析出及表面粗糙度的改变

目的：研究口腔内3种合金共存下的离子析出及表面粗糙度的改变,为临床合金修复材料的选择提供参考。方法：制作镍铬合金、钴铬合金和金银钯合金标准试件,分为镍铬合金（N组）、钴铬合金（C组）、金银钯合金（A组）、镍铬合金与金银钯合金（NA组）和镍铬合金与钴铬合金（NC组）5组。浸泡于标准电解质溶液（T=37 ℃,pH=2.31）中,每组平行重复4次。7 d后,用电感耦合等离子体质谱仪检测各组浸提液中离子析出量;用原子力显微镜观察各组试件表面形貌,测量表面粗糙度。采用SPSS 18.0软件包对数据进行统计学分析。结果：析出的镍离子量N组为（1.32±0.03） μg/cm², NA组为(2.13±0.07) μg/cm²,NC组为(1.53±0.08) μg/cm²,NA组、NC组均显著多于N组,NA组显著多于NC组（P<0.05）;析出的铬离子量N组为(0.06±0.01) μg/cm²,NA组为(0.08±0.01) μg/cm²,NC组为(0.05±0.01) μg/cm²,NA组显著多于NC组（P<0.05）。镍铬合金的表面粗糙度N组为(4.60±0.16) nm,NA组为(5.37±0.08) nm,NC组为(5.04±0.15) nm,NA组、NC组均显著大于N组,NA组显著大于NC组（P<0.05）。镍铬合金与金银钯合金或钴铬合金共存时,析出的镍离子量比其单独使用时明显增多,其表面粗糙度明显增大;镍铬合金与金银钯合金共存时比镍铬合金与钴铬合金共存时析出的镍、铬离子量多,镍铬合金的表面粗糙度也大。结论：临床上应尽量避免在患者口腔内同时应用镍铬合金与金银钯合金,或镍铬合金与钴铬合金,尽量避免贱金属的临床使用。     

Retrieval analysis of different orthodontic brackets: the applicability of electron microprobe techniques for determining material heterogeneities and corrosive potential

Objective

The objective of this study was to investigate the applicability of micro-analytical methods with high spatial resolution to the characterization of the composition and corrosion behavior of two bracket systems.

Material and methods

The surfaces of six nickel-free brackets and six nickel-containing brackets were examined for signs of corrosion and qualitative surface analysis using an electron probe microanalyzer (EPMA), prior to bonding to patient''s tooth surfaces and four months after clinical use. The surfaces were characterized qualitatively by secondary electron (SE) images and back scattered electron (BSE) images in both compositional and topographical mode. Qualitative and quantitative wavelength-dispersive analyses were performed for different elements, and by utilizing qualitative analysis the relative concentration of selected elements was mapped two-dimensionally. The absolute concentration of the elements was determined in specially prepared brackets by quantitative analysis using pure element standards for calibration and calculating correction-factors (ZAF).

Results

Clear differences were observed between the different bracket types. The nickel-containing stainless steel brackets consist of two separate pieces joined by a brazing alloy. Compositional analysis revealed two different alloy compositions, and reaction zones on both sides of the brazing alloy. The nickel-free bracket was a single piece with only slight variation in element concentration, but had a significantly rougher surface. After clinical use, no corrosive phenomena were detectable with the methods applied. Traces of intraoral wear at the contact areas between the bracket slot and the arch wire were verified.

Conclusion

Electron probe microanalysis is a valuable tool for the characterization of element distribution and quantitative analysis for corrosion studies.     

Mixed platinum–gold electrocatalysts for borohydride oxidation prepared by the galvanic replacement of nickel deposits

Mixed platinum/gold coatings were prepared by partial galvanic replacement of nickel layers that had been electrodeposited onto glassy carbon electrode substrates. The process (termed “transmetalation”) involves the spontaneous replacement of surface Ni atoms by Pt and Au upon immersion of the former metal into equimolar mixed chloroplatinic and chlorolaurate acid solutions. The multimetallic deposits on glassy carbon substrates, PtAu(Ni)/GC, were characterised by SEM/EDS, XRD, AES and electrochemical techniques. Smooth films with a bulk composition enriched in Au and minimum quantities of Ni left were obtained. Pt and Au were found to be alloyed and both Pt and Au to co-exist with Ni down to the core of the layers. The PtAu(Ni) deposits displayed typical Pt and Au surface electrochemistry indicating the formation of a continuous noble metal shell; the estimated electroactive surface areas point again to an excess of Au on the surface. The activity of the PtAu(Ni)/GC electrodes towards the oxidation of borohydride was studied by voltammetry at a rotating disc electrode, RDE, and compared to that of bulk Pt and Au. As expected, the Pt–Au alloy catalyst showed behaviour intermediate to that of its pure components. However, in the limiting current potential range the alloy tended more to bulk Au behaviour (number of electrons was closer to eight) while at low overpotentials it resembled the catalytic activity of pure Pt.     

THE ELECTROCHEMICAL PROPERTIES OF FOUR DENTAL CASTING SUPRASTRUCTURE ALLOYS COUPLED WITH TITANIUM IMPLANTS

Objectives:

As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions.

Material and Methods:

The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests.

Results:

The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples.

Conclusions:

Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.