Metal-ceramic restorations are an important component of modern oral reconstruction because they combine the strength, toughness, accuracy and marginal adaptation of metals with the permanent esthetic appearance of ceramics. The overall clinical survival rates for metal-ceramic restorations are still far superior to those of the all-ceramic systems. The evolution of dental metal-ceramic systems reflects two trends: 1) the search for economical alternatives to expensive noble metal alloys, and 2) the increased demand for biocompatible materials. Since titanium offers both low unit cost and biocompatibility, its use in prosthodontics has been increasing. Because of its active nature, melted titanium reacts with investment materials to form a reaction structure on the cast titanium surface, which prevents strong titanium-ceramic bonding. Complete removal of this structure will sacrifice the precise fit of the casting and is clinically unacceptable. The long- term goal of this study is to improve cast titanium-ceramic bonding and to understand titanium-ceramic bonding mechanisms. The objectives are to improve titanium-ceramic bonding by minimizing the formation of surface reaction structure on cast titanium, and to determine how various factors contribute to strong titanium- ceramic bonding. The central hypothesis of the proposed research is that cast titanium-ceramic adhesion will be significantly improved by minimizing the formation of the surface reaction structure on cast titanium. The hypothesis was formulated based on the results of supportive preliminary studies. The rationale underlying the investigation is that the surface reaction structure can be minimized by face-coating patterns with oxides that are more stable than titanium oxides at temperatures near titanium solidification. We anticipate testing the central hypothesis and achieving the objectives of this application by pursuing the following three Specific Aims: 1) to identify the most effective face-coating oxide that improves cast titanium-ceramic bonding; 2) to characterize cast CP titanium surfaces prepared from oxide face- coated patterns before and after the simulated porcelain firing cycles; and 3) to characterize the titanium-ceramic interfaces. It is our expectation that improved titanium-ceramic bonding will be achieved as a result of this study. The results will provide significant insight into the fundamental mechanisms of titanium- ceramic bonding and will be used for future development of titanium casting techniques and improved titanium-ceramic systems. This development will advance the titanium-ceramic systems that are more biocompatible and economical than current metal-ceramic systems, thereby benefitting the general public.
| Lee, K M; Cai, Z; Griggs, J A et al. (2004) SEM/EDS evaluation of porcelain adherence to gold-coated cast titanium. J Biomed Mater Res B Appl Biomater 68:165-73 |
