Two-stage photocuring process for a dental composition

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.

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.