Dental alloy sorting by the thermoelectric method.
OBJECTIVE
A nondestructive, rapid, and practical method of dental alloy sorting is desirable. In this study, the hypothesis to be tested is that dental alloys show significantly different and high thermoelectric power values, on the basis of which alloy sorting is possible.


METHODS
Six silver-colored commercial dental casting alloys are used in this study: two silver alloys, one gold-silver-palladium alloy, one cobalt-chromium alloy, one nickel-chromium alloy, and one titanium alloy. The thermoelectric power of their castings was determined against constantan using a simple apparatus developed in a previous study. Linear least square fitting was applied to the measured thermal-EMF-temperature curve to determine the thermoelectric power for the temperature ranges of 298-303 K (temperature difference Deltat = 5 K), 298-308 K (Deltat=10 K), 298-313 K (Deltat=15 K), and 298-318 K (Deltat=20 K). The results were analyzed using one-way ANOVA and by the Scheffé's test at a significance level of alpha=0.01.


RESULTS
When the temperature difference was 10 K or less, the difference in the thermoelectric powers of the alloys was not always statistically significant. However, when the temperature difference was 15 K or more, the thermoelectric powers of the six alloys differed significantly.


CONCLUSIONS
The results indicated the feasibility of rapid sorting of specific dental alloys by the thermoelectric method, provided a sufficiently large temperature difference is achieved.
Kikuchi
Masafumi
M
Division of Dental Biomaterials, Tohoku University Graduate School of Dentistry, Sendai, Miyagi 980-8575, Japan.