Abstract: Disclosed is a method for producing silica-zirconia composite oxide particles each coated with a silica layer, which is characterized in that a liquid dispersion of silica-zirconia composite oxide particles is obtained by reacting an alkoxide of silicon and/or a condensable compound derived from the alkoxide with an alkoxide of zirconium and/or a condensable compound derived from the alkoxide in a water-containing solvent that contains acetonitrile so that the reaction liquid is to contain not less than 10% by mass of acetonitrile, and then the surface of each silica-zirconia composite oxide particle is coated with a silica layer by reacting the silica-zirconia composite oxide particles dispersed in the liquid dispersion with an alkoxide of silicon and/or a condensable compound derived from the alkoxide in the liquid dispersion of silica-zirconia composite oxide particles.

Abstract: Disclosed is a method for producing silica-zirconia composite oxide particles each coated with a silica layer, which is characterized in that a liquid dispersion of silica-zirconia composite oxide particles is obtained by reacting an alkoxide of silicon and/or a condensable compound derived from the alkoxide with an alkoxide of zirconium and/or a condensable compound derived from the alkoxide in a water-containing solvent that contains acetonitrile so that the reaction liquid is to contain not less than 10% by mass of acetonitrile, and then the surface of each silica-zirconia composite oxide particle is coated with a silica layer by reacting the silica-zirconia composite oxide particles dispersed in the liquid dispersion with an alkoxide of silicon and/or a condensable compound derived from the alkoxide in the liquid dispersion of silica-zirconia composite oxide particles.

Abstract: A method of preparing a ceramic artificial crown by applying at least one kind of dental porcelain onto the surface of a ceramic core molded by heating and softening a ceramic material and putting it into a mold with the application of pressure followed by firing wherein said mold is the one formed by burning a wax pattern after having removed a crucible former from an assembly which makes it possible to efficiently prepare a fully ceramic artificial crown of a high quality in a short period of time.

Abstract: A method of preparing a ceramic artificial crown by applying at least one kind of dental porcelain onto the surface of a ceramic core molded by heating and softening a ceramic material and putting it into a mold with the application of a pressure followed by firing; wherein said mold is the one formed by burning a wax pattern after having removed a crucible former from an assembly which makes it possible to efficiently prepare a fully ceramic artificial crown of a high quality in a short period of time.

Abstract: A method of preparing a ceramic artificial crown by applying at least one kind of dental porcelain selected from the group consisting of a body porcelain, an incisal porcelain and a translucent porcelain onto the surface of a ceramic core molded by heating and softening a ceramic material and putting it into a mold with the application of a pressure followed by firing; wherein

Abstract: A pressure molding apparatus comprises a furnace defining a heating space for accommodating a mold assembly including a mold body charged with a raw material to be molded, and a pressure piston for pressurizing the raw material; heating means for heating the heating space; and load imposing means for imposing a load on the pressure piston to mold the raw material. The load imposing means includes at least one weight means and weight supporting means. The weight supporting means is selectively set in a load-free state in which the weight supporting means supports the weight means so that the weight of the weight means is not imposed on the pressure piston, and a load imposed state in which the weight supporting means releases the support of the weight means so that the weight of the weight means is imposed on the pressure piston.

Abstract: Provided is a porcelain which is suitable as a dental porcelain capable of being fired on a ceramics core and has a low firing temperature and a low thermal expansion coefficient and which is excellent in a chemical durability. The above dental porcelain comprises glass containing silicon oxide, aluminum oxide, boron oxide, zinc oxide, sodium oxide and lithium oxide as principal components. The contents of these respective components in the above glass are 57 to 65% by weight of SiO2, 8 to 18% by weight of Al2O3, 15 to 25% by weight of B2O3, 0.1 to 2% by weight of ZnO, 3 to 7% by weight of Na2O and 2 to 8% by weight of Li2O respectively in terms of a percent by weight based on the total of the respective components when the respective components are reduced to SiO2, Al2O3, B2O3, ZnO, Na2O and Li2O respectively. The particularly preferred dental porcelain comprises glass having a thermal expansion coefficient of 6.0×10−6 (1/°C.) or less as a principal structural component.