Dental compositions

Claim 1

A method of coating a tooth to provide the tooth with a curved layer of a dental composition for sealing dental fissures, dental glazing and/or orthodontic bonding, said method comprising the sequential steps of: (i) applying a liquid dental composition to a surface of a tooth, said composition comprising: (A) a polymerizable vinyl urethane prepolymer which is the reaction product of (a) a urethane prepolymer having the structure: OCN--(R.sub.1 --NH--CO--OR.sub.2 --O--OC--NH)--.sub.n R.sub.1 NCO derived by the reaction of a diisocyanate of the structure OCN--R 1 NCO and a diol of the structure HO--R 2 --OH, where R 1 in at least 80% of the urethane prepolymer units is aliphatic and contains 4 to 8 carbon atoms, inclusive, n is an integer not greater than 10, and R 2 is the residue of a condensate of not more than 8 moles alkylene oxide per mole of a compound containing two phenolic groups or the residue of an alkylene glycol, and (b) hydroxyalkyl acrylate or methacrylate; (B) 50% to 150% by weight of A of a liquid glycol diacrylate or dimethacrylate, and a photosensitive catalyst which comprises (C) 0.25 to 0.75 parts by weight per 100 parts by weight of A+B of at least one organic amine, and (D) 0.3 to 1.0 parts by weight per 100 parts by weight of A+B of at least one α-diketone which is selected from norbornane dione and substituted derivatives thereof; (ii) allowing the liquid dental composition to flow over a predetermined area of the tooth surface; and (iii) polymerizing the dental composition by exposure to visible radiation of a wavelength in the range of 400-500 μm to form said cured layer.

Claim 2

A method of coating a tooth to provide the tooth with a curved layer of a dental composition for sealing dental fissures, dental glazing and/or orthodontic bonding, said method comprising the sequential steps of: (i) applying a liquid dental composition to a surface of a tooth, said composition comprising: (A) a polymerizable vinyl urethane prepolymer which is the reaction product of (a) a urethane prepolymer having the structure: OCN--(R.sub.1 --NH--CO--OR.sub.2 --O--OC--NH)--.sub.n R.sub.1 NCO derived by the reaction of a diisocyanate of the structure OCN--R 1 NCO and a diol of the structure HO--R 2 --OH, where R 1 in at least 80% of the urethane prepolymer units is aliphatic and contains 4 to 8 carbon atoms, inclusive, n is an integer not greater than 10, and R 2 is the residue of a condensate of not more than 8 moles alkylene oxide per mole of a compound containing two phenolic groups or the residue of an alkylene glycol, and (b) hydroxyalkyl acrylate or methacrylate; (B) 50% to 150% by weight of A of a liquid glycol diacrylate or dimethacrylate, and a photosensitive catalyst which comprises (C) 0.25 to 0.75 parts by weight per 100 parts by weight of A+B of at least one organic amine, and (D) 0.3 to 1.0 parts by weight per 100 parts by weight of A+B of at least one α-diketone which is selected from norbornane dione and substituted derivatives thereof; (ii) allowing the liquid dental composition to flow over a predetermined area of the tooth surface; and (iii) polymerizing the dental composition by exposure to visible radiation of a wavelength in the range of 400-500 μm to form said cured layer.