Pororosity analysis in dental alloys cast with three heat sources

Abstract

The purpose of this study was to evaluate the porosity of complete crowns made ofpalladium-silver (Pors-on) and silver-palladium (Palliag-M) alloys. For the casting of the alloys, three heat sources were used: acetilen-oxigen, gasoxigen and electric resistance. Thirty specimens were prepared with casting wax in stainless steel die, and divided into two groups of 15 specimens each, according to the alloy used. Then, the specimens were subdivided into three groups of5 specimens each, accordingto the heat sources. Then a:ftercasting, the specimens were finished and polished. Two methods were used to determine the porosity of the specimens: densitometric and microscopic ones. In the densitometric determination, the alloydensities before and after casting were compared. For the microscopic observation, the specimens were cut, polished and then evaluated using scanning electronic microscopy. The results showed that the highest porosity occurred when acetilenoxigenheat sourcewas used, followed by gas-oxigen and electric sources. This was observed in both methods. ln general, the Palliag-M alloy showed more trend to the higher levels of porosity than the Pors-on 4 alloy,in both methods of evaluation. Key words: porosity, metal ceramic alloys, dental casting technique.