LOW-FUSING COUNTERDIES FOR MEASURING ACCURACY OF DIES OR IMPRESSION MATERIALS

Described in this pilot study is the genesis, development, and use of a system for measuring impression and die material accuracy with low-f using bismuth alloy counterdies. The method followed the same sequence used in dental laboratory technology with the assumption that the err ors associated with the wax pattern, investing, and casting had been l argely eliminated. Determination of the alloy shrinkage was the first step, followed by a comparison of two impression and two die materials used in conjunction with master dies of full crown and MOD configurat ions. Misfit measurements revealed marginal openings of 12 to 219 mu m depending on die configuration, the impression, or the die material. A 2 x 2 factorial statistical model with interaction revealed main and interactive effects. This procedure could be useful in future investi gations.