Glass-ceramics, process of producing the glass-ceramics and dental crown

Abstract

Disclosed is glass-ceramics produced by and a method of producing the glass-ceramics comprising the step of precipitating a calcium-potassium mica crystal consisting of Ca-K-Mg-Al-Si-O-F and at least one crystal selected from the group consisting of an enstatite crystal, an akermanite crystal and a diopside crystal, from glass containing components, in percent by weight, 2 to 17% of CaO, 0.5 to 5% of K.sub.2 O, 20 to 35% of MgO, 30 to 50% of SiO.sub.2, 5 to 30% of Al.sub.2 O.sub.3, and 1.5 to 14% of Fluorine (Calculated as F); or precipitating a calcium-potassium-sodium mica crystal consisting of Ca-K-Na-Mg-Al-Si-O-F and at least one crystal selected from the group consisting of an enstatite crystal, an akermanite crystal, a diopside crystal, an anorthite crystal and a richterite crystal, from glass containing components, in percent by weight, 2 to 17% of CaO, 0.5 to 5% of K.sub.x O, 0.1 to 4% of Na.sub.2 O, 15 to 35% of MgO, 30 to 49% of SiO.sub.2, 5 to 30% of Al.sub.2 O.sub.3, and 1.5 to 14% of Fluorine (calculated as F). In the above method, the glass is heat treated successively at a temperature higher than its glass transition point by a range of from 10.degree. to 100.degree. C. and at a temperature higher than its glass transition point by a range of from 100.degree. to 500.degree. C. to thereby precipitate the above-mentioned matters. Further disclosed is an artificial dental crown composed of the above-mentioned glass-ceramics.