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KMID : 0352119920080010012
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Journal of Kyung Hee University
1992 Volume.8 No. 1 p.12 ~ p.21
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A Study on the Casting Accuracy of Dental Base Metal Alloys
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Abstract
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The purpose of this study was to evaluate the fit and accuracy of dental castings made from commercially available Ni-Cr alloys designed for use in fixed prosthodontics, and it was assumed that there are some technical factors concerning casting
accuracy that need additional study. Those included in this investigation were alloy kinds and variables related to investment such as burnout temperature, number of liners, colloidal silica, and hygroscopic expansion. The experiment consisted of
fabricating and fitting castings to each resin replicas and measuring the marginal gap in four selected points.
@ES The following conclusions may be drawn from this experiment:
@EN 1) The casting accuracy may be related mainly to the expansion compensation of the phosphate bonded investment and the conditions of manipulations such as burnout temperature and the numbers of liners.
2) It was found that the nickel-chromium alloys produced castings that had a tight fit and showed marginal gap even under conditions designed to yield the maximum expansion of the investment. An improved investment capable of higher expansion is
needed
to obtain better results with nickel-chromium alloys.
3) When the colloidal silica liquid was diluted in order to reduce expansion, poor accuracy of casting body appeared. To gain maximum expansion of phosphate bonded investment which is needed for alloys that melt at high temperature, it is
necessary to
use undiluted silica sol with the investment.
4) The water-immersion, hygroscopic technique for phosphate bonded investment yield the poor results.
5) Alloy composition may also influence the accuracy of the casting, but further research is determine their singlular effects.
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