Effects of magnesia and potassium sulfate on gypsum-bonded alumina dental investment for high-fusing casting.
The purpose of this study was to improve the characteristics of gypsum-bonded alumina investments using magnesia and potassium sulfate as chemical additives. Magnesia content improved fluidity, delayed setting reaction, increased green strength, and decreased setting expansion, when mixed with distilled water. When the investment was mixed with potassium sulfate, the setting time and setting expansion were reduced, and the thermal expansion increased, however, the green strength decreased. Therefore, the investment with a small amount of magnesia mixed with potassium sulfate was considered a suitable composition, having adequate setting behavior, enough green strength and sufficient compensate expansion for casting.
Yan
M
M
Department of Dental Technology I, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Takahashi
H
H
D000537:Aluminum Oxide / Q000737:chemistry*; D002133:Calcium Sulfate / Q000737:chemistry; D019245:Compressive Strength; D003734:Dental Casting Investment / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D013816:Thermodynamics; D013997:Time Factors; D014961:X-Ray Diffraction
D003734:Dental Casting Investment; D008277:Magnesium Oxide; D000537:Aluminum Oxide; D002133:Calcium Sulfate