Curable composition for producing a dental composite crown and process of production

1. A curable composition for producing dental composite crowns, the curable composition comprising

a resin matrix comprising:

polymerizable (meth)acrylate(s) not comprising a urethane moiety present in an amount of 40 to 85 wt %, and

polymerizable urethane(meth)acrylate(s) present in an amount from 1 to 35 wt %;

a filler matrix present in an amount of 5 to 45 wt %, the filler matrix comprising:

nanocluster(s) present in an amount of 5 to 40 wt %,

optionally fumed silica present in an amount below 8 wt. %,

wherein any optional fumed silica excludes (meth)acrylate silane surface treatment;

an initiator system comprising:

photoinitiator(s) present in an amount of 0.01 to 3 wt %, and

organic dye(s) present in an amount of 0.001 to 0.5 wt %; and

a softener in an amount of no greater than 5 wt. %,

wherein the curable composition is characterized by a viscosity below 150 Pa*s at 23° C. and a shear rate of 1 s −1 , and

wherein wt. % is with respect to the weight of the curable composition.

2. The curable composition of claim 1 ,

the resin matrix being present in an amount of 40 to 85 wt. %,

wherein wt. % is with respect to the weight of the curable composition.

3. The curable composition of claim 1 , being characterized by one or more of the following features:

curable by radiation having a wavelength of in the range of 350 to 600 nm;

viscosity: 1 to 100 Pa*s at 23° C. at a shear rate of 1 s −1 ; and

pH value: 6 to 8.

4. The curable composition of claim 1 , comprising a fumed silica characterized by one or more of the following features:

BET surface: 100 to 300 m 2 /g; and

being surface-treated with an alkyl silane.

5. The curable composition of claim 1 , the composition comprising:

fumed silica present in an amount of 0.5 to 5 wt. %.

6. The curable composition of claim 1 , comprising one or more of the following components:

X-ray visible particles present in an amount of 0.1 to 5 wt. %

stabilizer, present in an amount of 0.001 to 0.5 wt. %; and

pigments, present in an amount of 0.001 to 0.5 wt. %;

wherein wt. % is with respect to the weight of the curable composition.

7. The curable composition of claim 1 , the composition not comprising one or more of the following components:

redox initiator system;

fumed silica surface treated with (meth)acrylate silanes in an amount of more than 2 wt. %; and

glass or glass ceramic particles in an amount of more than 5 wt. %,

wherein wt. % is with respect to the weight of the curable composition.

8. The curable composition of claim 1 , being characterized as follows:

polymerizable (meth)acrylate(s) not comprising a urethane moiety, comprising at least two (meth)acrylate moieties,

having a molecular weight of 170 to 3,000 g/mol, and

the polymerizable urethane(meth)acrylate(s), comprising at least three urethane moieties,

having a molecular weight of 450 to 3,000 g/mol, and

nanocluster comprising Si or Zr based particles, and

optionally fumed silica being present in an amount of 0.5 to 7 wt. %,

X-ray visible particles being present in an amount of 0 to 15 wt. %

photoinitiator comprising a phosphine oxide moiety, and

stabilizer being present in an amount of 0.001 to 0.5 wt. %,

wherein wt. % is with respect to the weight of the curable composition.

9. A cured article obtained by radiation curing the curable composition of claim 1 .

10. The cured article of claim 9 , being characterized by one or more of the following features:

flexural strength: 50 to 200 MPa determined according to ISO 4049:2009;

E-modulus: 1,000 to 4,000 MPa determined according to DIN EN 843-2:2007;

impact strength: 5 to 15 kJ/m 2 determined according to DIN 53453:175-05;

abrasion: less than 20 mm 3 ;

being autoclaveable; and

being tooth coloured.

11. The cured article of claim 9 , having the shape of a dental crown, bridge, inlay, onlay, veneer, table-top, or part thereof.

12. A kit of parts comprising at least two cured articles of claim 9 , the cured articles having the shape of a dental crown and differing from each other in one or more of the following features: size; colour; and shape.

13. A kit of parts comprising:

at least one cured article of claim 9 , the cured article having the shape of a dental crown, and

one or more of the following items:

self-adhesive dental cement; and

instruction for use.

14. A process for producing a cured article, the process comprising:

providing a curable composition of claim 1 ; and

processing the curable composition by applying an additive-manufacturing technique,

wherein the processing comprises radiation.

15. The process of claim 14 , the processing of the curable composition comprising:

producing a cured article precursor with a 3d-printer having a vat,

removing the cured article precursor from the vat of the 3d-printer,

cleaning the cured article precursor,

post-curing the cured article precursor to obtain a cured article, and

optionally polishing at least parts of the surface of the cured article.