A new ceramic dental mold can cast excellent Ti restoratives by controlling expansion due to the oxidation of additive metal particles. The packing structure of the metal and aggregate particles in the mold can be considered a function of the size distribution of the aggregate grains. An investigation of the expansion mechanism reveals three different relationships of void fraction versus linear thermal expansion for the molds at the high temperature under which oxidation of the metal particles occurs. Room‐temperature casting, favorable for making high‐quality Ti restoratives, can also be achieved by precisely controlling both the amount of additive metal powder and the compositional distribution of aggregate grain sizes in the m