The present invention relates to a glass ceramic material comprising a core-rim structure, wherein the core-rim structure comprises an amorphous SiO.sub.2 matrix, ZrO.sub.2 crystals, and hardness-enhancing additive, the ZrO.sub.2 crystals are present in cores that are at least partly surrounded by a rim comprising hardness-enhancing additive.

The present invention relates to a glass ceramic material comprising a core-rim structure, wherein the core-rim structure comprises an amorphous SiO.sub.2 matrix, ZrO.sub.2 crystals, and hardness-enhancing additive, the ZrO.sub.2 crystals are present in cores that are at least partly surrounded by a rim comprising hardness-enhancing additive.

Radically polymerizable dental material which contains at least one compound of Formulae I to III: ##STR00001## The material preferably additionally contains a radically polymerizable monomer, an initiator for the radical polymerization and filler. It is characterized in particular by a low polymerization contraction stress.

Lithium silicate glass ceramics and precursors thereof are described, which comprise copper and are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

Lithium silicate glass ceramics and precursors thereof are described, which contain tin and are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

What is described is a dental light-curable composition for elective production of a visible restoration in the anterior region or for filling of a cavity in the posterior region, comprising a total amount (A) of free-radically polymerizable monomers, where this total amount (A) consists of one, two, three or more than three free-radically polymerizable monomers and has a refractive index n.sub.A, 470nm in the range from 1.470 to 1.560, a total amount (B1) of nonaggregated and nonagglomerated inorganic filler particles having a particle size in the range from 7 to 70 nm, where this total amount (B1) has a refractive index n.sub.B1, 470nm in the range from 1.460 to 1.570 and where this total amount (B1) is in the range from 10 to 30 percent by volume, based on the overall dental light-curable composition, a total amount (B2) of inorganic filler particles having a particle size in the range from 0.12 μm to 10 μm, where this total amount (B2) has a refractive index n.sub.B2,470nm in the range from 1.450 to 1.560, and a total amount (C) of photoinitiators.

ZrO.sub.2-toughened glass ceramics having high molar fractions of tetragonal ZrO.sub.2 and fracture toughness value of greater than 1.8 MPa.Math.m.sup.1/2. The glass ceramic may also include also contain other secondary phases, including lithium silicates, that may be beneficial for toughening or for strengthening through an ion exchange process. Additional second phases may also decrease the coefficient of thermal expansion of the glass ceramic. A method of making such glass ceramics is also provided.

ZrO.sub.2-toughened glass ceramics having high molar fractions of tetragonal ZrO.sub.2 and fracture toughness value of greater than 1.8 MPa.Math.m.sup.1/2. The glass ceramic may also include also contain other secondary phases, including lithium silicates, that may be beneficial for toughening or for strengthening through an ion exchange process. Additional second phases may also decrease the coefficient of thermal expansion of the glass ceramic. A method of making such glass ceramics is also provided.

To provide a dental lithium silicate glass composition capable of providing a dental lithium silicate glass ceramic capable of efficiently precipitating the main crystals (lithium disilicate and/or lithium metasilicate) even after heat treatment. To provide a Al.sub.2O.sub.3-free dental lithium silicate glass composition including the following components: SiO.sub.2: 60.0 to 80.0% by weight, Li.sub.2O: 10.0 to 17.0% by weight, K.sub.2O: 0.5 to 10.0% by weight, ZrO.sub.2: 0.0 to 5.0% by weight, a nucleating agent: 1.0 to 6.0% by weight, a glass stabilizer: 0.0 to 8.0% by weight and a colorant: 0.0 to 10.0% by weight.

The present invention relates to a method of fabricating an improved lithium silicate glass ceramic and to that material for the manufacture of blocks for dental appliances using a CAD/CAM process and hot pressing system. The lithium silicate material has a chemical composition that is different from those reported in the prior art with 1 to 10% of germanium dioxide in final composition. The softening points are close to the crystallization final temperature of 800° C. indicating that the samples will support the temperature process without shape deformation.