| 摘要 |
This invention is directed to lithium disilicate (Li2 Si2 O) based glass-ceramics comprising silica, lithium oxide, alumina, phosphorus pentoxide, and optionally potassium oxide or tantalum oxide. 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 an embodiment directed to the process of making the glass-ceramics, the starting compositions are melted at about 1200 DEG to about 1600 DEG 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 DEG to about 1100 DEG 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. |
