Two-stage photocuring process for a dental composition

Claim 2

A process for curing a photocurable dental composition comprising: first irradiating said dental composition comprising: (a) 5 to 70% by weight based on the weight of and (b), of an ethylenically unsaturated polymerizable monomer, an unsaturated polymer of said monomer or a mixture thereof, wherein said ethylenically unsaturated polymerizable monomer is an acrylate or a methacrylate, (b) 30 to 95% by weight, based on the weight of (a) and (b), of fillers, (c) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (I) having a light absorption maximum of <450 nm and a molar extinction coefficient of <10 at wavelengths of 470 nm or higher, (d) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (II) having a molar extinction coefficient of >20 at a wavelength of >450 nm, and (e) optionally pigments, X-ray-opaque additives, thixotropy adjuvants or mixtures thereof; with light of wavelengths >450 nm to effect partial curing of said dental composition to between 50 and 70% of its maximum hardness; and subsequently irradiating said dental composition with light including wavelengths <450 nm to effect complete curing of said dental composition.

Claim 3

The process according to claim 1, further comprising the step of removing excess amounts of said dental composition after said first irradiation step, but before said subsequent irradiation step.

Claim 4

The process according to claim 1, wherein said photoinitiator (II) and any activators therefor, are selected such that the surface hardness of said dental composition after partial curing is <200 MPa.

Claim 5

The process according to claim 3, wherein said photoinitiator (II) is an α-diketone.

Claim 6

The process according to claim 4, wherein said photoinitiator is camphor quinone.

Claim 7

The process according to claim 1, wherein said photoinitiator (I) has an absorption maximum from 360 to 410 nm.

Claim 8

The process according to claim 6, wherein said photoinitiator (I) has a molar extinction coefficient >25 at 400 nm.

Claim 9

The process according to claim 7, wherein said photoinitiator (I) is a bisacylphosphine oxide.

Claim 10

The process according to claim 8, wherein said bisacylphosphine oxide is represented by the formula: ##STR2## wherein R 1 is a straight-chain or branched C 1-18 -alkyl radical, a cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl radical; a cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl radical substituted with F, Cl, Br, I, C 1 -C 12 -alkyl, C 1 -C 12 -alkoxyl, or mixtures thereof; a S or N containing 5-membered or 6-membered heterocyclic ring, and R 2 and R 3 , which may be identical or different, each represents a cyclohexyl, cyclopentyl, phenyl, naphthyl, or biphenylyl radical; a cyclopentyl, cyclohexyl, phenyl, naphthyl, or biphenylyl radical substituted with F, Cl, Br, I, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxyl, or mixtures thereof; a S or N containing 5-membered or 6-membered heterocyclic ring; or R 2 and R 3 are joined to form a ring containing from 4 to 10 carbon atoms and optionally substituted by 1 to 6 C 1-4 -alkyl radicals.

Claim 11

The process according to claim 1, wherein the wavelengths of said first irradiation step are obtained by filtering out light with wavelengths <450 nm with a suitable optical cut-off filter and the wavelengths of said subsequent irradiation step are obtained by omitting said optical cutoff filter.

Claim 12

A process of preparing a dental tooth filling, said method comprising the steps of: Step 1) providing a two-stage curable dental composition comprising: (a) 5 to 70% by weight based on the weight of (a) and (b), of an ethylenically unsaturated polymerizable monomer, an unsaturated polymer of said monomer or a mixture thereof, wherein said ethylenically unsaturated polymerizable monomer is an acrylate or a methacrylate, (b) 30 to 95% by weight, based on the weight of (a) and (b), of fillers, (c) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (I) having a light absorption maximum of <450 nm and a molar extinction coefficient of <10 at wavelengths of 470 nm or higher, (d) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (II) having a molar extinction coefficient of >20 at a wavelength of >450 nm, and (e) optionally pigments, X-ray-opaque additives, thixotropy adjuvants or mixtures thereof; Step 2) shaping the dental composition to the desired shape; Step 3) irradiating said dental composition with light of wavelengths >450 nm, thus obtaining a partially-cured dental composition, with up to 70% of its maximum hardness; Step 4) removing any excess amount of said dental composition with carving tools; Step 5) irradiating said remaining dental compositions with light including wavelengths <450 nm, to obtain a fully-cured, dental tooth filling at its final hardness.

Claim 13

A process of preparing a dental tooth filling, said method comprising the steps of: Step 1) providing a two-stage curable dental composition comprising: (a) 5 to 70% by weight based on the weight of (a) and (b), of an ethylenically unsaturated polymerizable monomer, an unsaturated polymer of said monomer or a mixture thereof, wherein said ethylenically unsaturated polymerizable monomer is an acrylate or a methacrylate, (b) 30 to 95% by weight, based on the weight of (a) and (b), of fillers, (c) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (I) having a light absorption maximum of <450 nm and a molar extinction coefficient of <10 at wavelengths of 470 nm or higher, (d) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (II) having a molar extinction coefficient of >20 at a wavelength of >450 nm, and (e) optionally pigments, X-ray-opaque additives, thixotropy adjuvants or mixtures thereof; Step 2) shaping the dental composition to the desired shape; Step 3) irradiating said dental composition with light of wavelengths >450 nm, thus obtaining a partially-cured dental composition, with up to 70% of its maximum hardness; Step 4) removing any excess amount of said dental composition with carving tools; Step 5) irradiating said remaining dental compositions with light including wavelengths <450 nm, to obtain a fully-cured, dental tooth filling at its final hardness.

Claim 14

The method of claim 11, wherein in the two-stage curable dental composition: the photoinitiator (I) comprises a bisacylphosphine oxide of the general formula: ##STR3## wherein R 1 is a straight-chain or branched C 1-18 -alkyl radical, a cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl radical; a cyclohexyl, cyclopentyl, phenyl, naphthyl or biphenylyl radical substituted with F, Cl, Br, I, C 1 -C 12 -alkyl, C 1 -C 12 -alkoxyl, or mixtures thereof; a S or N containing 5-membered or 6-membered heterocyclic ring, and R 2 and R 3 , which may be identical or different, each represents a cyclohexyl, cyclopentyl, phenyl, naphthyl, or biphenylyl radical; a cyclopentyl, cyclohexyl, phenyl, naphthyl, or biphenylyl radical substituted with F, Cl, Br, I, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxyl, or mixtures thereof; a S or N containing 5-membered or 6-membered heterocyclic ring; or R 2 and R 3 are joined to form a ring containing from 4 to 10 carbon atoms and optionally substituted by 1 to 6 C 1-4 -alkyl radicals.

Claim 15

A process for mounting sufficiently transparent dental inlays, onlays and facing shells, comprising the following steps: Step 1) fastening said inlay, onlay or facing shell to a tooth with a composition comprising; (a) 5 to 70% by weight based on the weight of (a) and (b), of an ethylenically unsaturated polymerizable monomer, a polymer of said monomer or a mixture thereof, wherein said ethylenically unsaturated polymerizable monomer is an acrylate or a methacrylate, (b) 30 to 95% by weight, based on the weight of (a) and (b), of fillers, (c) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (I) having a light absorption maximum of <450 nm and a molar extinction coefficient of <10 at wavelengths of 470 nm or higher, (d) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (II) having a molar extinction coefficient of >20 at a wavelength of >450 nm, and (e) optionally pigments, X-ray-opaque additives, thixotropy adjuvants or mixtures thereof; Step 2) irradiating the composition in a first curing step with light of wavelengths >450 nm, forming a resultant mounted product; Step 3) carving any excess composition from the rim of the mounted product with carving instruments, to form a finished product; and Step 4) irradiating the finished product in a final curing step with light including wavelengths <450 nm, securing the finished product to the tooth.

Claim 16

A process for mounting sufficiently transparent dental inlays, onlays and facing shells, comprising the following steps: Step 1) fastening said inlay, onlay or facing shell to a tooth with a composition comprising; (a) 5 to 70% by weight based on the weight of (a) and (b), of an ethylenically unsaturated polymerizable monomer, a polymer of said monomer or a mixture thereof, wherein said ethylenically unsaturated polymerizable monomer is an acrylate or a methacrylate, (b) 30 to 95% by weight, based on the weight of (a) and (b), of fillers, (c) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (I) having a light absorption maximum of <450 nm and a molar extinction coefficient of <10 at wavelengths of 470 nm or higher, (d) 0.05 to 3% by weight, based on the weight of (a), of a photoinitiator (II) having a molar extinction coefficient of >20 at a wavelength of >450 nm, and (e) optionally pigments, X-ray-opaque additives, thixotropy adjuvants or mixtures thereof; Step 2) irradiating the composition in a first curing step with light of wavelengths >450 nm, forming a resultant mounted product; Step 3) carving any excess composition from the rim of the mounted product with carving instruments, to form a finished product; and Step 4) irradiating the finished product in a final curing step with light including wavelengths <450 nm, securing the finished product to the tooth.