Komasa Y, Moriguchi A, Asai M, Nezumi M, Kakimoto K, Gonda Y
First Department of Prosthodontics, Osaka Dental University, Japan.
J Osaka Dent Univ. 1998 Oct;32(2):47-57.
We evaluated the effect of impression materials used in preparation of pure titanium castings on the surface reactive layer. Surface roughness of the refractory models before and after firing was smaller when silicone rather than agar impression material was used. The surface roughness of castings prepared with T-invest varied little with the impression material. However, the surface roughness of the castings prepared with CD Titaninvest was less when silicone impression material was used. Surface hardness of the castings was slightly greater when agar impression material was used, and metallic texture analysis of the surface of the castings showed a chill layer and a columnar crystal layer extending from the surface toward the interior. A relatively non-corroded white layer and a markedly corroded black layer were observed in the chill layer, and their thickness was smaller when silicone impression material was used. Use of the Electron Probe Micro Analyzer (EPMA) to determine distribution of various elements in the superficial layer of the casting plates showed that the reactive layer contained less P and Si when silicone impression material was used rather than agar. NH4H2 PO4, which is a component of the bonding material in the investment, was present at a high concentration in the superficial layer of the agar impression material. This shows the importance of preparing refractory models with a non-water-absorbing impression material to obtain pure titanium casting plates with a smaller reactive layer.
我们评估了用于纯钛铸件制备的印模材料对表面反应层的影响。使用硅橡胶而非琼脂印模材料时，焙烧前后耐火模型的表面粗糙度更小。使用T-invest制备的铸件表面粗糙度随印模材料变化不大。然而，使用CD Titaninvest制备铸件时，使用硅橡胶印模材料时铸件的表面粗糙度更小。使用琼脂印模材料时，铸件的表面硬度略高，铸件表面的金相组织分析显示有一个激冷层和一个从表面向内部延伸的柱状晶层。在激冷层中观察到一个相对未腐蚀的白色层和一个明显腐蚀的黑色层，使用硅橡胶印模材料时它们的厚度更小。使用电子探针微分析仪（EPMA）测定铸板表层各种元素的分布表明，使用硅橡胶印模材料而非琼脂时，反应层中的P和Si含量更少。作为包埋料中粘结材料成分的NH4H2PO4在琼脂印模材料的表层中浓度较高。这表明使用不吸水的印模材料制备耐火模型对于获得具有较小反应层的纯钛铸板很重要。
