1997 Volume 17 Issue 3 Pages 191-196
Titanium is a promising metal in a prosthetic field and one of the application is the metal frame work for veneering with resin composites. However, there is little information on the reconstruction of retention beads on titanium castings that is a practical structure to bond resin composites on conventional metal frameworks. Therefore, in this study reconstruction of retention beads on titanium castings was examined by preparing castings using commercial investments and a casting machine.
Three sizes of retention beads (Average particle sizes : 600,200,100μm) were adhered on thin wax sheets (12×12×0.3 mm in thickness) and invested with two commercial investments for titanium (Magnesia-based investment and Magnesia-alumina-based investment). After the molds were fired according to the manufacturer's instruction, titanium (JIS grade 2) was cast into the mold using a commercial arc melting centrifugal casting machine with a rotational speed 3000 rpm. Castability of the wax patterns and reconstruction of fine retention beads were evaluated macroscopically and the contamination on the surface of the castings was evaluated by SEM and Raman spectroscopy.
The structure of retention beads prepared on the wax pattern was successfully reconstructed on the titanium castings obtained from both molds by a centrifugal casting method. However, SEM observation and Raman spectroscopy indicated that investment material still remained on the surface of the castings among the retention beads even after sandblasting. Especially, cast titanium surface with bigger beads had a larger contamination from investment than that with smaller beads. Therefore, we need other tail treatments on titanium castings to remove contamination from investment or we suggest to use an alternative method such as a non-retention beads method to apply titanium for veneered crowns.
