A Clinical Study n Discoloration of the Dental Casting Alloys

本研究旨在评价口腔金属铸造材料抛光表面的变色和附着情况.结果表明，在离体条件下，CH_3SH、H_2S的产生与Au-Ag-Pd合金的变色有关。Au-Ag-Pd合金的变色还可能与牙周病、口臭、口腔护理等口腔条件有关.变色的防止受到Ag-Pd-Au合金的组成（Cu：10.0 ~ 20.0质量%，Au：12.0 ~ 20.0质量%）的影响。但对于口腔腐蚀性强的患者，目前的成分很难防止市售Ag-Pd-Au合金变色.铸造卡环通常使用Ag-20 Pd-12 Au合金铸造。铸造后的热处理工艺为：1）800℃保温1h，水淬; 2)在800℃下加热1小时，然后空气冷却。作为对照，铸造卡环未经热处理。虽然两种热处理和对照之间的亮度有显着差异，但在分娩后的所有条件下，亮度均显着降低。热处理对高变色率的材料影响不大. 3例患者配合安装纯钛和银钯铜金合金义齿，各义齿正常使用2个月。变色试样的表面被证实覆盖着球形增生。在X射线光电子能谱仪中用氩离子刻蚀去除了钛的堆积物，确认其厚度为0.3 ~ 0.5μm。而Ag-Pd-Cu-Au合金中的吸积层由于被氩离子刻蚀去除，其厚度无法估算。

The present study was to evaluate discoloration and accretion on the polished surface of dental cast metal in the oral cavity.1. The findings indicated in vitro that the production of CH_3SH, H_2S was related to the discoloration of Au-Ag-Pd alloy. The dicoloration of Au-Ag-Pd alloy may also be related to the oral conditions such as periodontics, halitosis and oral care.2. The prevention of discoloration was influenced by composition of Ag-Pd-Au alloys (Cu : 10.0〜20.0 mass%, Au 12.0 or 20.0 mass%). But it was difficult to prevent to the discoloration of commercially available Ag-Pd-Au alloys with the current compositions for patients having high corrosive influence on the mouth.3. Cast clasps ware conventionally cast using Ag-20Pd-12Au alloy. After casting, the heat treatment was performed as wing manners : 1) Heated at 800℃ for 1 hour and quenched in water. 2) Heated at 800℃ for 1 hour and air cooled. As a control, cast clasps without heat treatment. Although there are significant differences in the luminance among two heat treatment and control, the luminance was markedly decreased in all conditions after delivery. On the high discoloration subjects heat treatments might be little effect.4. The pure titanium and Ag-Pd-Cu-Au alloy were installed in the partial denture by cooperating in three patients and each denture was used as usual for two months. The surfaces of the discolored specimens were confirmed to be covered with the spherical accretion. The accretion of titanium was taken away by Argon ion etching in X-ray Photoelectron Spectroscopy and its thickness was confirmed to be 0.3〜0.5μm. However, the thickness of the accretion in Ag-Pd-Cu-Au alloy could not been estimated because it was taken away by Argon ion etching.