Abstract
To make the casting of titanium with a calcia investment practical for dental use, the improvement of mold treatments and the dimensional fitness of castings were investigated. Lapping the mold with cooking film immediately after investing caused a high strength of mold and resulted in ringless casting. Because of small setting and thermal expansion of the original calcia investment, the dimensional fitness of casting was achieved by utilizing the oxidizing expansion of Zr metal powder mixed in a calcia investment. The calcia investment improved in the study produced a titanium casting with a shiny surface without reaction with the mold, with a good dimensional fitness, and with fewer casting defects inside.
