To investigate how the surface roughness and the surface elements of dental porcelain were changed by hydrofluoric acid, the porcelain specimens were etched by 2.5%, 5%, 7,5%, 10%, 15%, 20% hydrofluoric acids during 30 sec, 1 min, 2 min, 5 min, 10 min time periods, at 37C, and they were analyzed with the surface roughness tester, SEM, and EDAX.
The results were as follows:
1. The surface roughness of etched dental porcelains were increased by the increase of etching time, but the ratio of increase was low after cerain time.
2. The roughness of etched surfaces in relation to the increase of hydrofluoric acid concentration did not increase continuously.
3. The etched appearance were observed obviously by SEM.
4. In the EDAX analysis, the compositional ratio of Si decreased and that of Al, K, Ca increased over 10% hydrofluoric acid.
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