Patent ID: 8129443

Claim:
A powder of a cured product of a polymerizable composition comprising: (A) an inorganic oxide having an X-ray contrast property and an average particle diameter of 100 nm or smaller, said inorganic oxide being that of at least one element selected from the group consisting of Ti, Zr and lanthanide, (B) a surface modifier comprising an alkoxysilane, said alkoxysilane being selected from the group consisting of γ-methacryloxypropyl methyl dimethoxysilane and γ-methacryloxypropyl trimethoxysilane and the amount of said surface modifier being 100 to 500 parts by weight based on 100 parts by weight of the inorganic oxide (A), (C) a polymerizable compound, said inorganic oxide being uniformly dispersed in the polymerizable compound (C), and (D) a polymerization initiator, whose cured product having a thickness of 2.0 mm shows a light transmittance at a visible light wavelength of 560 nm of 1% or higher and an X-ray contrast property in terms of Al equivalent of 45% or higher; and said powder having an average particle diameter of 1 to 100 μm.