DENTAL CASTING OF TITANIUM ALLOYS

牙用脱蜡铸造技术一直是主流

Dental casting by means of the lost-wax technique has been the dominant method of fabricating crowns and bridges for many years. However, since the end of the 1970's, efforts have been made to case fixed and removable dental prostheses using commercially pure (CP) titanium, which has mechanical properties similar to ADA Types I-IV gold alloys. The overwhelming advantage of titanium over other metals is its excellent biocompatibility, which is important because of increasing concerns about the toxicity of biomedical materials. In addition, titanium is an economical metal ($30/oz vs. $350/oz for a precious alloy) and is in abundant supply. Many of the initial problems with dental titanium casting arising from the inherent characteristics of titanium have now been solved. There are presently various kinds of commercial casting equipment and investment materials available which were specifically developed for dental titanium casting. However, further refinement of titanium casting technology remains to be done, particularly the casting alloys. The main goal of this proposal is to develop titanium alloys which have a low fusing temperature and high oxidation resistance which will result in casting performance, mechanical and corrosion properties , biocompatibility, and machinability equal or superior to CP titanium and ADA Type IV gold alloy. Specifically, the proposed project will attempt first to find suitable casting conditions for the NIOM/Baylor titanium casting equipment for CP titanium and Ti-6AI-4V. After the casting technology is refined with this equipment, binary candidate alloys will be screened based on mechanical properties and corrosion resistance. Experimental binary and ternary alloys (based on the screened binaries) will be evaluated in terms of casting performance, mechanical properties, corrosion behavior, microstructure, and biocompatibility. Advancements in the machinability of the selected experimental alloys will be attempted by alloying small amounts of elements noted for improving this property. Finally, the nature of porcelain bonding will be evaluated on selected experimental titanium alloys. The present research group believes the proposed study to be an important step for the advancement of this "technique-sensitive" process to a more practical level. There is great potential for titanium in dental casting applications and to ignore it would be a disservice to the public. In order for th e public to benefit, however, more work needs to be done on perfecting all aspects of the titanium casting technology. This is the work that this proposal addresses.