Dental Casting of Titanium Alloys

钛为生物医学和牙科应用提供了理想的优势：它对人体无毒。在钛的实际应用方面，牙科一直落后于医学。之前和提议的研究背后的动机是更多地了解这种金属，以便充分开发其在牙科领域的潜力。在之前的资助期间(1996-2000年)，我们对牙科钛铸造的几个方面进行了研究，并对铸造工艺本身、对牙科有希望的实验合金以及生产可用于牙科修复的铸件的方法有了大量的了解。最初的项目期为所有领域的进一步研究奠定了基础；这项更新建议是该研究计划的合乎逻辑的进展。我们建议通过将我们的研究扩展到三元和多元合金来提炼我们已经学到的东西。我们将研究高合金钛(合金元素超过5%)、低合金钛(合金元素低于5%)和钛金属间化合物。我们的一般假设是，这些改进的合金系统将产生与目前使用的牙科铸造合金相等甚至可能超过的性能。额外的测试将在辅助领域提供更多知识，例如通过在模具表面涂层来减少熔融金属与包埋材料的反应。除了拉伸疲劳评估外，还将使用无缺口三角棱柱断裂韧性测试来检查断裂韧性和抗疲劳性。将通过有限元建模检查模具填充情况，以预测气泡的发生。用三维有限元模型分析合金与瓷面的粘结强度。选定的合金将用典型的测试方法进行细胞毒性测试。具体目标如下：1)评估拟议的实验二元、三元和多元合金(包括金属间化合物)的机械性能，以满足牙科应用的要求；2)根据可接受的牙科修复体在充型、铸造精度和亚表面结构方面的要求，检查铸造实验合金的质量；3)评估实验合金的腐蚀行为和生物相容性；4)检测牙科应用所需的铸造实验合金的特性，包括与瓷器的结合强度、可加工性和磨损行为；以及5)评估实验铸造合金的抗疲劳和断裂韧性。

Titanium offers an ideal advantage for biomedical and dental applications: it is nontoxic to humans. Dentistry has lagged behind medicine in practical applications of titanium. The motivation behind the previous and the proposed studies is to learn more about this metal in order to develop its full potential for dentistry. In the previous grant period (1996- 2000), we performed studies on several aspects of dental titanium casting and gained a great deal of knowledge on the casting process itself, on the experimental alloys showing promise for dentistry, and on methods of producing castings that will be acceptable for dental prostheses. The initial project period laid the groundwork for further study in all areas; this renewal proposal is a logical progression of this research program. We propose to refine what we have already learned by expanding our study to ternary and multicomponent alloys. We will study high alloy titanium (greater than 5 percent alloying elements), low alloy titanium (less than 5 percent alloying elements), and titanium intermetallic compounds. Our general hypothesis is that these refined alloy systems will produce properties equaling and possibly surpassing those of presently used dental casting alloys. Additional testing will provide more knowledge in ancillary areas, such as in reducing the reaction of the molten metal to the investment material through face-coating the mold. In addition to tensile fatigue evaluation, fracture toughness and fatigue resistance will be examined using a notchless triangular prism fracture toughness test. Mold filling will be examined by finite element modeling to predict void occurrence. Bond strength of the alloys to porcelain will be analyzed with 3-D finite element modeling. Selected alloys will be examined for cytotoxicity with typical testing methods. The specific aims to be addressed are: 1) to evaluate the proposed experimental binary, ternary, and multicomponent alloys (including intermetallics) for mechanical properties pertinent to the requirements for dental applications; 2) to examine the quality of the cast experimental alloys based on the requirements for acceptable dental prostheses in the areas of mold filling, casting accuracy, and subsurface structures; 3) to evaluate the corrosion behavior and biocompatibility of the experimental alloys; 4) to examine the characteristics of cast experimental alloys necessary for dental applications, including bond strength to porcelain, machinability, and wear behavior; and 5) to evaluate the fatigue resistance and fracture toughness of the experimental cast alloys.