Abstract: A method of repairing teeth which comprises applying to the teeth a composition comprising (a) an inert, translucent, inorganic particulate filler (b) a polymerizable material comprising a polymerizable prepolymer containing at least two polymerizable ethylenically unsaturated groups and being the reaction product of a urethane prepolymer and a polymerizable ethylenically unsaturated monomer reactive with the urethane prepolymer; the urethane prepolymer being the reaction product of a diisocyanate and a diol; up to 100% by weight of the polymerizable prepolymer of a liquid ethylenically unsaturated monomer which is copolymerizable with the polymerizable prepolymer; and from 0.01 to 10% by weight of the polymerizable material of a photosensitive catalyst capable of curing the composition on exposure to visible light and comprising a photosensitizer selected from fluorenone and an .alpha.-diketone of the formula A.CO.CO.

Abstract: A photopolymerizable composition comprising at least one polymerizable ethylenically unsaturated material, for example, an ethylenically unsaturated monomer, and a photosensitive catalyst comprisingA. at least one photosensitizer having the structure ##STR1## where X is >C=O, >CR.sub.1 R.sub.2 or >CR.sub.3 OR.sub.4, especially >C=O, R.sub.1 to R.sub.4 and hydrogen or hydrocarbyl groups, n is 0 or 1, and the groups A are hydrocarbyl or substituted hydrocarbyl groups, the groups A being aromatic or substituted aromatic when n is 1 and X is >CR.sub.1 R.sub.2 and when n is 0, andB. at least one reducing agent, for example, an amine or a phosphine, capable of reducing the photosensitizer when the photosensitizer is in an excited state.