Mercieca Sven, Caligari Conti Malcolm, Buhagiar Joseph, Camilleri Josette
1 Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Msida - Malta.
2 Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Malta, Msida - Malta.
J Appl Biomater Funct Mater. 2018 Jan;16(1):47-54. doi: 10.5301/jabfm.5000383.
The aim of this study was to compare the degradation resistance of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys used as a base material for partial dentures in contact with saliva.
Wiron® 99 and Wironit Extra-Hard® were selected as representative casting alloys for Ni-Cr and Co-Cr alloys, respectively. The alloys were tested in contact with deionized water, artificial saliva and acidified artificial saliva. Material characterization was performed by X-ray diffractometry (XRD) and microhardness and nanohardness testing. The corrosion properties of the materials were then analyzed using open circuit potential analysis and potentiodynamic analysis. Alloy leaching in solution was assessed by inductively coupled plasma mass spectrometry techniques.
Co-Cr alloy was more stable than the Ni-Cr alloy in all solutions tested. Leaching of nickel and corrosion attack was higher in Ni-Cr alloy in artificial saliva compared with the acidified saliva. The corrosion resistance of the Co-Cr alloy was seen to be superior to that of the Ni-Cr alloy, with the former exhibiting a lower corrosion current in all test solutions. Microstructural topographical changes were observed for Ni-Cr alloy in contact with artificial saliva. The Ni-Cr alloy exhibited microstructural changes and lower corrosion resistance in artificial saliva. The acidic changes did not enhance the alloy degradation.
Ni-Cr alloys are unstable in solution and leach nickel. Co-Cr alloys should be preferred for clinical use.
本研究旨在比较用作局部义齿基托材料的镍铬（Ni-Cr）合金和钴铬（Co-Cr）合金在与唾液接触时的抗降解性。
分别选用Wiron® 99和Wironit Extra-Hard®作为Ni-Cr合金和Co-Cr合金的代表性铸造合金。将合金分别与去离子水、人工唾液和酸化人工唾液接触进行测试。通过X射线衍射仪（XRD）、显微硬度和纳米硬度测试进行材料表征。然后使用开路电位分析和动电位分析来分析材料的腐蚀性能。通过电感耦合等离子体质谱技术评估合金在溶液中的浸出情况。
在所有测试溶液中，Co-Cr合金比Ni-Cr合金更稳定。与酸化唾液相比，Ni-Cr合金在人工唾液中的镍浸出和腐蚀侵蚀更高。Co-Cr合金的耐腐蚀性优于Ni-Cr合金，在所有测试溶液中前者的腐蚀电流更低。观察到Ni-Cr合金与人工唾液接触时微观结构表面发生变化。Ni-Cr合金在人工唾液中表现出微观结构变化和较低的耐腐蚀性。酸性变化并未增强合金的降解。
Ni-Cr合金在溶液中不稳定且会浸出镍。临床应用中应优先选择Co-Cr合金。
