Dental Casting of Titanium Alloys

钛为生物医学和牙科应用提供了一个理想的优势：它对人类无毒。牙科在钛的实际应用方面落后于医学。先前和提议的研究背后的动机是更多地了解这种金属，以开发其在牙科方面的全部潜力。在之前的资助期间（1996- 2000），我们对牙科钛铸件的几个方面进行了研究，并获得了大量关于铸造工艺本身的知识，关于实验性合金在牙科方面的前景，以及关于生产可用于牙科修复的铸件的方法。项目初期为各领域的进一步研究奠定了基础；这个更新建议是这个研究计划的一个合乎逻辑的进展。我们建议通过将我们的研究扩展到三元和多组分合金来完善我们已经学到的东西。研究高合金钛（合金元素含量大于5%）、低合金钛（合金元素含量小于5%）和钛金属间化合物。我们的一般假设是，这些精炼的合金系统将产生相当于甚至可能超过目前使用的牙科铸造合金的性能。额外的测试将在辅助领域提供更多的知识，例如通过对模具进行表面涂层来减少熔融金属对投资材料的反应。除了拉伸疲劳评估，断裂韧性和抗疲劳性能将使用无缺口三角棱柱断裂韧性测试进行检查。模具填充将通过有限元建模来预测空洞的发生。用三维有限元模型分析合金与陶瓷的结合强度。选定的合金将用典型的测试方法进行细胞毒性测试。具体目标是：1)评估拟议的实验性二元、三元和多组分合金（包括金属间化合物）与牙科应用要求相关的机械性能；2)根据可接受的口腔修复体在模具填充、铸造精度和地下结构方面的要求，检查铸造实验合金的质量；3)评价实验合金的腐蚀行为和生物相容性；4)检查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、可加工性和磨损性能；5)评价试验铸造合金的抗疲劳性能和断裂韧性。

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.