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Surface Roughness and Marginal Fit of Gold Crowns and Gold-Silver-Palladium Crowns Made with Accelerated-type Gypsum-bonded Investments

Purpose : Recently, many kinds of accelerated-type investments were introduced into the market. With this kind of material, the time spent on the casting procedure is greatly shortened compared with the time required for casting in conventional investments. The purpose of this study was to investigate the fit and surface roughness of crowns made from two kinds of alloys cast in the accelerated gypsumbonded investments and to compare the results with results using a conventional investment.Materials and Methods : Four kinds of accelerated investments and one kind of conventional investment, and two kinds of alloys (12% gold-silver-palladium and Type III gold alloy) were used in this study. The mean surface roughness, maximum height and marginal discrepancy of the crowns were measured and statistically analyzed using a t-test.Results : The fit and surface roughness of crowns for both alloys made with the accelerated investments were not statistically different compared with the conventional investment. The values for fit and surface roughness of the Type III gold alloy crowns were less than for the 12% gold-silver-palladium alloy crown (p<0.05). There were no significant differences between alloys for any of the four kinds of accelerated investments.Conclusion : These results suggested that the casting performance of the accelerated investments was similar to that of the conventional investment.