M. Koike, T. Okabe, Baylor College of Dentistry, Dallas, TX
The use of titanium for medical and dental prostheses began with commercially pure titanium (CP Ti) some 15 years ago. Because the strength of CP titanium is limited, it was necessary to find a stronger alloy for this purpose. Thus, Ti-6Al-4V has been widely tested and used for various applications. However, there were concerns about one of the alloy constituents (vanadium) from the standpoint of biocompatibility. Although an alternative alloy, Ti-6Al-7Nb, was introduced, a more economical alloy would be preferable. Thus, we investigated some Ti-5Al-Cu alloys using Cu in place of V in Ti-6Al-4V. The various characteristics we investigated for dental applications included mechanical properties, corrosion behavior, grindability and wear resistance. Four experimental alloys, one binary Ti-5 (mass%) Al and three ternary Ti-5Al alloys with 1, 3 and 5% Cu were prepared by melting high-purity Al and Cu together with Ti sponge in an argon-arc melting furnace. Specimens were made by casting these alloys and commercial Ti-6Al-4V into MgO-based investment molds in a centrifugal casting machine. The yield and tensile strengths and percent elongation of Ti-5Al-5Cu were comparable to those of Ti-6Al-4V (P>0.05). The strength was reduced with decreasing Cu contents while the ductility increased with decreasing Cu contents. The anodic polarization results revealed that all metals tested completely passivated in the normal intraoral potential ranges (-58 to 212 mV). The grindability of Ti-5Al-5Cu tested using a SiC wheel was statistically better than that of Ti-6Al-4V and the other tested alloys (P<0.01). The wear resistance of Ti-5Al and Ti-5Al-5Cu tested in equipment that simulated chewing action was statistically better than that of Ti-6Al-4V (P<0.01). With further refinements, Ti-Al-Cu alloy could be a good candidate for some dental applications. This study was partially funded by NIH grant DE11787.
