Curable composition

A curable composition comprising:

• (i) a polymerizable monomer;
• (ii) amorphous inorganic particles (A) consisting chiefly of silica-zirconia and 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;
• (iii) spherical inorganic particles (B) consisting chiefly of silica-zirconia and having an average particle diameter of from 0.1 to 5 .mu.m;
• (iv) inorganic fine particles (C) consisting chiefly of at least one inorganic oxide selected from the group consisting of silica, alumina, silica-zirconia, and silica-titania and having an average particle diameter of from 0.01 to 0.1 .mu.m;
• and
• (v) a polymerization initiator;
• wherein the irregular-shaped inorganic particles (A), spherical inorganic particles (B) and inorganic fine particles (C) are used in a total amount of from 500 to 1200 parts by weight per 100 parts by weight of the polymerizable monomer, and, when the total amount of the spherical inorganic particles (B) and the inorganic fine particles (C) is set to be 100% by weight, the spherical inorganic particles (B) are used in an amount of from 60 to 90% by weight and the inorganic fine particles (C) are used in an amount of from 40 to 10% by weight, the weight ratio ›(A)/{(B)+(C)}! of the irregular-shaped inorganic particles (A) to the total amount of the spherical inorganic particles (B) and the inorganic fine particles (C) is from 0.7 to 1.5, and wherein the irregular-shaped inorganic particles (A), spherical inorganic particles (B) and inorganic fine particles (C) in a state of being mixed together have an integrated volume of strongly aggregated pores having pore diameters of not smaller than 0.08 .mu.m of not larger than 0.1 cc/g, and the polymerization initiator is used in an amount of from 0.01 to 5 parts by weight per 100 parts by weight of the polymerizable monomer.