Sutow Elliott J, Maillet Wayne A, Hall Gordon C
Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, 5981 University Avenue, Halifax, NS, Canada B3H 3J5.
Dent Mater. 2006 Apr;22(4):325-9. doi: 10.1016/j.dental.2005.06.001. Epub 2005 Aug 8.
The corrosion potential of a dental amalgam restoration is generally determined using a single measurement, even though environmental factors and abrasion can continuously alter the surface state and reactivity of this alloy. It was, therefore, the purpose of this study to determine the maximum variability of the corrosion potential of aged dental amalgam restorations, for 28 days.
The corrosion potentials of 148 aged dental amalgam restorations in 12 human subjects were measured at t = 0 and 4 h, and 4, 7, 14, 21 and 28 days. Measurements were made with a high impedance voltmeter and a Ag/AgCl micro-reference electrode. The subjects were instructed not to alter their usual eating and oral hygiene routines.
Corrosion potential changes occurred throughout the 28 days. They were both positive and negative for the same restoration, and were sometimes very large. Only 4 h after the initial measurement, the absolute value of the corrosion potential changes ranged between 18 and 287 mV for 50% of the restorations. The largest maximum absolute corrosion potential change for each subject's restorations ranged between 85 and 329 mV. Statistical analysis showed that the overall mean maximum absolute corrosion potential change for the subjects' restorations was 74 mV.
It was shown that the corrosion potential of aged dental amalgam restorations varies substantially over time, and that a single measurement is not representative of short- or long-term electrochemical behavior. This finding has implications regarding the corrosion rate of dental amalgam restorations, particularly those that are part of a galvanic couple.
尽管环境因素和磨损会持续改变牙科汞合金修复体的表面状态和反应性，但通常仍使用单次测量来确定其腐蚀电位。因此，本研究的目的是确定老化28天的牙科汞合金修复体腐蚀电位的最大变异性。
对12名受试者的148个老化牙科汞合金修复体在t = 0、4小时以及4、7、14、21和28天时的腐蚀电位进行测量。使用高阻抗电压表和Ag/AgCl微参比电极进行测量。要求受试者不要改变其日常饮食和口腔卫生习惯。
在整个28天内都发生了腐蚀电位变化。同一修复体的变化既有正值也有负值，有时变化幅度很大。在首次测量仅4小时后，50%的修复体腐蚀电位变化的绝对值在18至287 mV之间。每个受试者修复体的最大绝对腐蚀电位变化范围在85至329 mV之间。统计分析表明，受试者修复体的总体平均最大绝对腐蚀电位变化为74 mV。
结果表明，老化牙科汞合金修复体的腐蚀电位会随时间发生显著变化，单次测量不能代表其短期或长期的电化学行为。这一发现对牙科汞合金修复体的腐蚀速率具有重要意义，尤其是对于那些作为电偶一部分的修复体。
