The present invention relates to a glass ceramic for veneering a dental frame structure, wherein said glass ceramic is characterized by a high content of B.sub.2O.sub.3, to a process for the preparation thereof, and to the use thereof in the production of dental restorations.

The invention relates to a medical form body of lithium silicate glass ceramic. To increase its strength it is proposed that a surface compressive stress is created in a form body of lithium silicate glass, or containing lithium silicate glass, through the replacement of lithium ions by alkali metal ions of greater diameter. For this purpose the form body is covered with a paste that contains alkali metal.

To provide a dental porcelain paste which can maintain maintaining the paste state and have excellent application property for a long period of time and hardly causes carbonization or bubbles due to the influence of an organic component or a polymer component during firing. The present invention provides a dental porcelain paste for preparing a dental prosthesis device, comprising: 50.0 to 80.0 wt. % of a glass powder (a) having a maximum particle diameter of 100 m or less and an average particle diameter of 1 to 20 m, 0.5 to 10.0 wt. % of a hydrophobized fine particle silica (b) having an average primary particle diameter of 1 to 50 nm, and 10.0 to 49.5 wt. % of an organic solvent (c) having a boiling point it is within (bp) of 100 to 300 C.

A dental polymerizable composition including a glass powder and a (meth)acrylate is provided. The glass powder includes zinc, silicon, and fluorine and is substantially free of aluminum.

A process for the preparation of multi-coloured glass ceramic blanks for dental purposes is described, in which lithium silicate glasses with different compositions are introduced into a mould in order to form a glass blank, the glass blank is optionally compacted by pressing, the glass blank is heat-treated in order to obtain a glass ceramic blank with lithium silicate as main crystal phase, and the glass ceramic blank is compacted by hot pressing.

The invention relates to glass-ceramics based on the lithium silicate system which can be mechanically machined easily in an intermediate step of crystallisation and, after complete crystallisation, represent a very strong, highly-translucent and chemically-stable glass-ceramic. Likewise, the invention relates to a method for the production of these glass-ceramics. The glass-ceramics according to the invention are used as dental material.

The invention relates to glass ceramics and glasses with cerium and tin content, which comprise the following components:

TABLE-US-00001 Component wt.-% SiO.sub.2 42.0 to 80.0 Al.sub.2O.sub.3 0.1 to 42.0 Cerium, calculated as CeO.sub.2 0.5 to 10.0 Tin, calculated as SnO 0.1 to 4.0
and which are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth.

The invention relates to glass ceramics and glasses with a europium content, containing the following components:

TABLE-US-00001 Component wt.-% SiO.sub.2 30.0 to 75.0 Al.sub.2O.sub.3 10.0 to 45.0 Europium, calculated as Eu.sub.2O.sub.3 0.05 to 5.0
and which are suitable in particular for the production of restorations, the fluorescence properties of which largely correspond to those of natural teeth.

The invention relates to a method to produce a medical form body of lithium silicate glass ceramic. To increase its strength it is proposed that a surface compressive stress is created in a form body of lithium silicate glass, or containing lithium silicate glass, through the replacement of lithium ions by alkali metal ions of greater diameter. For this purpose the form body is covered with a paste that contains alkali metal.

The invention relates to a method for the preparation of a lithium silicate glass or a lithium silicate glass ceramic which comprise cerium ions and are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth. The invention also relates to a lithium silicate glass and a lithium silicate glass ceramic which can be obtained using the method according to the invention, the use thereof as dental material and in particular for the preparation of dental restorations, as well as a glass-forming composition which is suitable for use in the method according to the invention.