Abstract
The correlation between permebility and castability was investigated using four dental casting techniques (centrifugal, normal air pressure, peripheral air pressure and vaccum casting). Four dental investments, which had different permeability coefficients, were utilized for this study. Coil type wax patterns were used for measuring the castability (Fig.1). Shell type investment samples for measuring the permeability were shaped by silicone rubber cut mold. Castability was indicated by casting ratio which is the value of cast length divided by the whole length of coil pattern. Permeability of investment sample was measured at casting temperature by the method described in the second report. The effect of permeability on castability was changed due to casting methods. 1. In centrifugal and normal air pressure castings, higher permeability gave higher casting ratio. 2. In peripheral air pressure casting, higher permeability decreased casting ratio. 3. In vaccum casting, higher permeability increased casting ratio.
