Department of Dental and Biomedical Materials Science, Unit of Basic Medical Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Japan.
Dent Mater J. 2010 May;29(3):330-5. doi: 10.4012/dmj.2009-093. Epub 2010 May 20.
This study evaluated the tarnish resistance of eight experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.1% Na(2)S aqueous solution at 37 degrees C. Color measurements of the plate samples were made using a computerized spectrophotometer before and after immersion in the test solution for up to 72 hours. Tarnish discoloration was evaluated using the color difference vector, DeltaE*, in the CIELAB color space. Microstructural observation of each sample through an optical microscope revealed the matrix phase as the major constituent and second-phase small grains in the matrix phase. Selective tarnish discoloration occurred in the matrix, and fractional area of the matrix to the whole surface area was influenced by the sum of Au and Ag concentrations. The DeltaE* value significantly decreased with increasing Au/(Au+Ag) atomic ratio. In conclusion, the Au/(Au+Ag) ratio in an alloy and the fractional area of the matrix were found to be primary and auxiliary factors affecting the tarnish resistance of the experimental alloys.
本研究评估了八种实验性 Pd 自由 Ag-Au-Pt-Cu 牙科合金在 37°C 的 0.1%Na(2)S 水溶液中的抗变色性。在将板样品浸入测试溶液中长达 72 小时前后，使用计算机分光光度计对其颜色进行测量。使用 CIELAB 颜色空间中的颜色差向量 DeltaE来评估变色变色。通过光学显微镜观察每个样品的微观结构显示出基体相作为主要成分和基体相中第二相的小颗粒。选择性变色发生在基体中，基体相对于整个表面积的分数面积受 Au 和 Ag 浓度总和的影响。DeltaE值随 Au/(Au+Ag)原子比的增加而显著降低。总之，合金中的 Au/(Au+Ag)比值和基体的分数面积被发现是影响实验合金抗变色性的主要和辅助因素。
