Calcium depleted aluminum fluorosilicate glass powder for use in dental or bone cements

US4376835A · kind A · utility

Assignee

• ESPE Fabrik Pharmazeutischer Praparate GmbH · DE

Inventors

• Werner Schmitt · Starnberg, DE
• Robert Purrmann · Starnberg, DE
• Peter Jochum · Meiningen, AT
• Oswald Gasser · Hanerau-Hademarschen, DE

Key dates

• Filing date: Jan 4, 1982
• Grant date: Mar 15, 1983
• Expiry date: Jan 4, 2002

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2996
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

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.