Development Of Investment Material For The IPS-Empress2 Heat-Pressed Ceramic

Purpose: IPS-Empress2 heat-pressed castable ceramic system is a successful all-ceramic prosthetic system in clinic. The purpose of this study is to develop a kind of domestic investment material that is comparable to the special investment material of IPS system to lower the cost of its clinical application. Method: We detect the main properties of IPS special investment material firstly as an index of our own domestic material. Then we make a prototype of our domestic material. Several specimens are obtained by altering the amount and proportion of some key ingredients. The main properties of each specimen are tested to select the best one. After the best one is determined, a thorough study is done on it. The SPSS statistics software evaluates the differences between our domestic material and the special material.Results: The setting time, setting expansion rate, total expansion rate, density before heating, density after heating, rate of open hole, compressive strength at 2 hours after setting and compressive strength after heating to 920 of the special investment material for IPS-Empress2 are 17.1minutes, 8.58 ‰, 11.7 ‰, 1.576g/cm3, 1.320g/cm3, 38.8‰, 0.71MPa and 6.07MPa respectively; while the setting time, setting expansion rate, total expansion rate, density before heating, density after heating, rate of open hole, compressive strength at 2 hours after setting and compressive strength after heating to 920 of our domestic investment material are 9 minutes, 7.98‰, 11.6‰, 1.813g/cm3, 1.402g/cm3,38.1%, 5.42MPa and 8.37MPa respectively. And it can bear the temperature of at least 1000 . There are no statistical differences in the setting expansion rate, total expansion rate, rate of open hole, density after heating between the two materials. The setting time of our material is statistically shorter. The compressive strength before and after heating, the density before heating of our domestic investment material are statistically higher than that of IPS special investment material. Under the scanning electronic microscope, the crystals of the phosphate hydrate in our domestic material are smaller than those in the IPS special material.Conclusion: The domestic investment material for the IPS-Empressl heat-pressed castable ceramic system is comparable to its special investment material, thus has a promising prospect of future clinical application.