The invention relates to a blank for producing a dental molded part such as an inlay, onlay, crown or bridge, and to a method for producing the blank. To be able to machine a dental molded part, in particular one having thin wall thicknesses, from the blank without difficulty, the blank is designed to consist of a glass ceramic having a density of between 30 and 60% of theoretical density, and of glass-ceramic powder particles with a particle size distribution d.sub.90≦80 μm, lithium silicate crystals being present in an amount of 10 to 90% by volume.

Provided is a method that can manufacture a glass material having excellent homogeneity by containerless levitation. A block (12) of glass raw material is heated and melted by irradiation with a plurality of laser beams with the block (12) of glass raw material held levitated, thus obtaining a molten glass, and the molten glass is then cooled to obtain a glass material. The plurality of laser beams include a first laser beam (13A) and a second laser beam (13B). A size () of an angle formed between the first laser beam (13A) and the second laser beam (13B) is 0 or more but less than 180. A center (C1) of a spot (S1) of the first laser beam (13A) on the surface of the block (12) of glass raw material and a center (C2) of a spot (S2) of the second laser beam (13B) on the surface of the block 12 of glass raw material are different from each other.

A method for manufacturing glass, including the steps of heat-melting a raw material for producing glass by using a melting furnace having a plurality of gas flow paths while the raw material is levitated from the melting furnace by a gas ejected from the gas flow paths, and performing cooling so as to produce glass, wherein the melting furnace includes a recess portion, at least one first gas flow path configured to eject the gas in the vertical direction into the recess portion, a plurality of second gas flow paths configured to eject the gas in the direction toward the center axis of the melting furnace into the recess portion, the raw material is heat-melted while the raw material is levitated by the gas ejected from the first gas flow path and the gas ejected from the second gas flow paths, and the molten raw material is cooled.

A method for producing a dental prosthesis based on lithium silicate glass or lithium silicate glass-ceramic, including the steps of: melting a powder mixture containing at least SiO.sub.2, Li.sub.2O, Al.sub.2O.sub.3; producing spherical, lens-shaped or rod-shaped glass particles solidified from the melt; portioning the glass particles and filling them into a crucible; melting the glass particles in the crucible and setting a viscosity v, wherein 4 dPa.Math.sv80 dPa.Math.s; casting the thus produced melt into a negative mold which is enclosed by an embedding compound and corresponds to the dental prosthesis and; solidifying the melt in the negative mold, and crystallizing lithium metasilicate and/or lithium disilicate from the solidified melt.

Provided is a method that can manufacture a glass material having excellent homogeneity by containerless levitation. A block (12) of glass raw material is heated and melted by irradiation with a plurality of laser beams with the block (12) of glass raw material held levitated, thus obtaining a molten glass, and the molten glass is then cooled to obtain a glass material. The plurality of laser beams include a first laser beam (13A) and a second laser beam (13B). A size () of an angle formed between the first laser beam (13A) and the second laser beam (13B) is 0 or more but less than 180. A center (C1) of a spot (S1) of the first laser beam (13A) on the surface of the block (12) of glass raw material and a center (C2) of a spot (S2) of the second laser beam (13B) on the surface of the block 12 of glass raw material are different from each other.