Abstract: A composite filler obtained by precuring the acrylate or methacrylate of a polyhydric alcohol having at least three ethylenically unsaturated groups in the molecule thereof by using a free-radical initiator in the presence of an inorganic filler, followed by grinding the resultant prepolymer is described. This composite filler remarkably improves the stiffness and hardness of organic resins and rubbers, and prevents a decrease in the impact strength and bending strength of organic resins and rubbers when the composite fillers are compounded into the organic resins and rubbers. Furthermore, a dental composition obtained from the polymerization of a vinyl compound in the presence of the above-mentioned composite filler is described. This dental composition has excellent properties, such as, high hardness, high strength, good adhesiveness, and is suitable for use as dental materials.

Abstract: A curable composition comprising an aromatic dibasic acid having an ethylenically unsaturated group, such as 4-methacryloxyethyltrimellitate, or an acid anhydride thereof, other ethylenically unsaturated monomer and a catalyst is disclosed. This composition is applied between articles to be bonded together and is polymerized and cured to form an adhesive layer excellent in the water resistance and durability. This composition is especially valuable as a dental adhesive or as an undercoating agent for a paint or adhesive.