Abstract
Casting shrinkage is compensated for by the stting expansion and thermal expansion of the investment material;the setting expansion may be obstructed by the wax pattern, thereby rendering the compensation inadegueate.The exothermic heat coincident with the setting may increase the flow of the wax, thus permitting sufficient setting expansion for proper compensation.We accordingly investigated the relationship between the time of kneading of four types of investment material, their volume, and the resulting increase in the mold temperature accompanying setting.The setting time decreased with an increase in the mixing time for all four materials.The mold temperature increased with the increase in mixing time for all four materials.For Dentivest only, the setting expansion decreased with a longer mixing time.Changes in the mixing time had no effect on thermal expansion.For Dentivest only, a longer mixing time improved the casting accuracy.For Cerami gold only, castings were overfit.Mold temperature and casting accuracy both increased with larger volumes of investment material for Ceravest G.
