US 6,455,451 B1
Pressable lithium disilicate glass ceramicsGeneral
US 6,455,451 B1
Pressable lithium disilicate glass ceramics
Tech Center:
1700 Chemical and Materials Engineering
Examiner:
C. Melissa Koslow
Art Unit:
1755 UNKNOWN
Agent:
ANN M KNAB
Inventors:
DMITRI BRODKIN; CARLINO PANZERA; PAUL PANZERA
Assignee:
Priority:
12/11/98
Filed:
12/10/99
Granted:
09/24/02
Expiration:
12/10/19
Abstract
This invention is directed to lithium disilicate (Li2Si2O5) based glass-ceramics comprising silica, lithium oxide, alumina, potassium oxide and phosphorus pentoxide. The glass-ceramics are useful in the fabrication of single and multi-unit dental restorations (e.g. anterior bridges) made by heat pressing into refractory investment molds produced using lost wax techniques. The glass-ceramics have good pressability, i.e., the ability to be formed into dental articles by heat-pressing using commercially available equipment. In accordance with one embodiment directed to the process of making the glass-ceramics, the compositions herein are melted at about 1200° to about 1600° C., thereafter quenched (e.g., water quenched or roller quenched) or cast into steel molds, or alternately, cooled to the crystallization temperature. The resulting glass is heat-treated to form a glass-ceramic via a one or two step heat-treatment cycle preferably in the temperature range of about 400° to about 1100° C. The resulting glass ceramics are then pulverized into powder and used to form pressable pellets and/or blanks of desired shapes, sizes and structures which are later pressed into dental restorations.