Abstract: Amorphous inorganic particles as a dental material includes silica and inorganic oxide(s) other than silica and has high x-ray impermeability. The inorganic particles as a dental material includes silica with the content in the range from 70 to 98 weight % and oxide(s) of one or more elements selected from the group of Zr, Ti, La, Ba, Sr, Hf, Y, Zn, AL, and B, wherein 5 to 70 weight % of the silica is originated from an acidic silicic acid solution and 30 to 95 weight % of the silica is originated from a sol of silica. The inorganic particles as a dental material have an average particle diameter in the range from 1 to 10 ?m, specific surface area in the range from 50 to 350 m2/g, pore volume in the range from 0.05 to 0.5 ml/g, amorphous crystallinity as observed by x-ray diffraction, and the refractive index in the range from 1.47 to 1.60.

Abstract: The present invention provides amorphous inorganic particles as a dental material comprising silica and inorganic oxide(s) other than silica and having high x-ray impermeability. The inorganic particles as a dental material comprise silica with the content in the range from 70 to 98 weight % and oxide(s) of one or more elements selected from the group consisting of Zr, Ti, La, Ba, Sr, Hf, Y, Zn, AL, and B, wherein 5 to 70 weight % of the silica is originated from an acidic silicic acid solution and 30 to 95 weight % of the silica is originated from a sol of silica. This inorganic particles as a dental material have average particle diameter in the range from 1 to 10 &mgr;m, specific surface area in the range from 50 to 350 m2/g, pore volume in the range from 0.05 to 0.5 ml/g, amorphous crystallinity as observed by x-ray diffraction, and the refractive index in the range from 1.47 to 1.60.