Effect of thickness of peridental restorations on the casting precision

The present study has shown that the precision of peridental gold alloy castings depends both on the specific properties of the investment used and on the thickness of the pattern. In all cases the inside diameter of the castings decreased with increasing thickness. The most accurate results were obtained with an experimental investment characterized by a setting expansion of 0.05%, a thermal expansion high enough to compensate for the alloy contraction during cooling from solidus to room temperature, and a compressive strength of only 27 kg/cm2 at 670 degrees C.