Abstract: A dental filling composition comprising(a) from 60 to 80% by weight of the composition of an inorganic particulate filler selected from glass, quartz or silica of which at least 50% of the particles have a maximum dimension of not greater than 300 microns, and(b) a polymerizable material comprising:A polymerizable prepolymer being the reaction product of a urethane prepolymer and 2-hydroxy-ethyl methacrylate;The said urethane prepolymer being the reaction product of a di-isocyanate selected from the group consisting of 4,4'-di-isocyanatodiphenylmethane, hexamethylene di-isocyanate, 4,4'-dicyclohexylmethane di-isocyanate and 2,4-tolylene di-isocyanate, and a diol being the condensate obtained by reacting 2,2-bis-(p-hydroxyphenyl)propane and propylene oxide in a molar ratio of 1:2;Up to 100% by weight of the polymerizable prepolymer of methacrylic acid or an ester of methacrylic acid selected from the group consisting of methyl methacrylate, ethylene glycol dimethacrylate, hydroxyethyl methacrylate, triethylene