Abstract: A curable composition comprising (i) a polymerizable monomer, (ii) irregular-shaped inorganic particles (A) having an average particle diameter of from 1 to 9 .mu.m, and containing particles having particle diameters of not smaller than 10 .mu.m in an amount of not larger than 3% by weight, such as silica-zirconia irregular-shaped particles, (iii) spherical inorganic particles (B) having an average particle diameter of from 0.1 to 5 .mu.m, such as spherical silica-zirconia particles; (iv) inorganic fine particles (C) having an average particle diameter of from 0.01 to 0.1 .mu.

Abstract: An inorganic composition comprises (A) 60 to 99% by weight of spherical inorganic oxide particles having a mean particle diameter greater than 0.1 .mu.m but not greater than 1 .mu.m, and (B) 40 to 1% by weight of inorganic oxide fine particles having a mean particle diameter not greater than 0.1 .mu.m, wherein a volume of micro pores due to strongly aggregated particles having pore diameters not smaller than 0.08 .mu.m is not greater than 0.1 cc per gram of the inorganic composition. The inorganic composition, when mixed with a polymerizable monomer and a catalyst, provides a composite useful for dental applications which has excellent surface smoothness, can be polished in a short time, exhibits improved bending strength, compressive strength, surface hardness and wear resistance and causes little wear on an antagonistic tooth.

Abstract: Disclosed is an amorphous, spherical inorganic compound having a particle size of 0.1 to 1.0 .mu.m, which comprises as main constituents (1) an oxide of at least one metal selected from the group consisting of metals of the Groups I, II, III and IV of the Periodic Table, said metal oxide being capable of combining with silicon dioxide, and (2) silica.

Abstract: A crystalline metal oxide in the form of a solid solution comprising an oxide of a metal of Group II of the periodic table, titanium oxide and silicon dioxide as main components and having main peaks at about 26.7.degree. and about 20.9.degree. in its Cu-K.alpha. X-ray diffraction pattern (2.theta.) and a specific refractive index. The crystalline metal oxide is produced, for example, by dissolving a compound of a metal of Group II of the periodic table, a hydrolyzable organic silicon compound and a hydrolyzable titanium compound in an organic solvent, hydrolyzing said starting compounds in said solution or after said solution is added to a separately prepared solvent incapable of dissolving the reaction product, thereby to form a sol- or gel-like product, and thereafter calcining the sol- or gel-like product at a temperature and for a period of time sufficient to crystallize said product.

Abstract: Disclosed is an amorphous, spherical inorganic compound having a particle size of 0.1 to 1.0 .mu.m, which comprises as main constituents (1) an oxide of at least one metal selected from the group consisting of metals of the Groups I, II, III and IV of the Periodic Table, said metal oxide being capable of combining with silicon dioxide, and (2) silica.