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AssigneeESPE Fabrik Pharmazeutischer Praparate GmbH
InventorsWerner Schmitt, Robert Purrmann, Peter Jochum, Oswald Gasser
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A calcium aluminum fluorosilicate glass powder is disclosed which has average particle size of at least 0.5 microns, and is characterized in that the calcium in the surface of the powder's particles is depleted so that the quotient of the atomic ratio Si/Ca at the surface of the particles and the atomic ratio Si/Ca in the core region of the particles is at least 2.0, more preferably at least 3.0 and most preferably at least 4.0. The glass powder may be prepared by surface treating calcium aluminum fluorosilicate glass powder particles with an acid which forms calcium salts, washing the calcium salts off the treated particles and drying the washed particles. The glass powder has utility in self-hardening glass ionomer cements, such as dental or bone cements. Cements formed from the glass powder exhibit reduced periods of water sensitivity, while permitting sufficient time for processing.
A calcium aluminum fluorosilicate glass powder reactable with a mixing fluid to form a self hardening glass ionomer cement exhibiting properties of reduced period of water sensitivity and at the same time insuring a sufficiently long processing period, said glass powder being characterized by particles having an average size of at least 0.5 microns, and in that the level of calcium present at the surface of the powder particles is depleted relative to the level of the calcium present in the core region and to the extent that the quotient of the atomic ratio Si/Ca at the surface of the powder particles and the atomic ratio Si/Ca in the core region is at least 2.0, with the calcium content increasing asymptotically from the surface to the core region.
Dependencies are inferred from the claim text.