Comparison Of The Physical And Mechanical Properties Among Four Kinds Of Die Stone Casts

Objective:To compare the physical and mechanical properties among four kinds of die stone casts (YCG, Dentona, Heraues, Suicheng).Methods:①A metal model imitating the rigid fixed bridge was utilized as the mould to make silicone rubber impression. Five experimental casts were made by silicone rubber impression for each kind. The dimensional sizes of the gypsum casts were measured with universal tool-measuring microscope.②A metal cudoid model (50mm×10mm×5mm) was utilized as the mould to make silicone rubber impression. Five experimental casts were made by the silicone rubber impression for each kind of four plasters.The bending resistance was tested with universal testing machine.③Five experimental casts (50mm×10mm×5mm) were made with the same method. Compressible strength was tested with universal testing machine.④Five experimental casts (50mm×100mm×5mm) were made with the same method. The surface roughness was tested with surface roughness tester. The data was analyzed using SPSS 16.0 software.Results:①The proximal-distal dimensional accuracy of four kinds of gypsum cast (YCG, Dentona, Heraeus, Huicheng) was 15.043,15.034,15.037 and 15.040 mm respectively, the buccolingual dimensional accuracy was 7.020,7.015,7.019 and 7.019 mm respectively, and the tooth long-axis dimensional accuracy was 8.022,8.018,8.019 and 8.021 mm respectively. There was no significant difference in dimensional accuracy (P> 0.05)②The bending resistance of the four kinds of gypsum cast was 15.687,13.000, 22.521 and 18.675 Mpa respectively. There was significant difference in bending resistance (P<0.05). The bending resistance of Heraeus die stone cast was significantly greater compared with the other 3 die stone casts (P<0.05), and the bending resistance of Huicheng die stone cast was significantly greater than that of Dentona die stone cast (P <0.05).③The compressible strength of the four kinds of gypsum cast was 60.592, 56.192,65.317 and 62.689 Mpa respectively. There was significant difference in bending resistance (P<0.05). The compressible strength of Heraeus die stone cast was significantly greater than that of Dentona die stone cast(P<0.05) and the compressible strength of Huicheng die stone cast was significantly greater than that of Dentona die stone cast (P<0.05).④The surface roughness of the four kinds of gypsum cast was 2.295, 2.258,2.174 and 2.185μm respectively. There was no significant difference in surface roughness (P> 0.05).Conclusion:①Heraeus die stone cast is greater than the other 3 die stone casts in the bending resistance, and greater than Dentona die stone cast in compressible strength. So Heraeus die stone is the first selection material among four kinds of die stone casts.②Suicheng die stone cast is greater than Dentona die stone cast in bending strength and compressible strength, and lower in price, which suggests Suicheng should be selected in clinic appropriately according to actual situation.