Cationically curing dental composition containing polymeric particles and use thereof

1. A curable dental composition comprising:

a cationically hardenable compound (A) comprising at least two aziridine moieties,

a starter (B) being suitable to cure the hardenable compound (A),

polymeric particles as filler component (C),

the polymeric particles having a maximum particle size of 150 μm or below and

the component(s) the polymeric particles are made of being based on fluoropolymers comprising more than 99% monomer repeating units of tetra fluoro ethylene.

2. The composition of claim 1 , filler component (C) being characterized by at least or all of the following parameters:

maximum particle size: 150 μm or below;

d50/μm: 50 or below;

d90/μm: 100 or below;

average particle size: 1 to 30 μm;

BET surface according to DIN ISO 9277: 1 to 20 m 2 /g;

bulk density according to DIN EN ISO 60: below 2 g/cm 3 or from 0.1 to 2 g/cm 3 ;

melting peak temperature according to DIN EN ISO 12086: above 100° C.;

Shore hardness A: below 70;

molecular weight: 10 4 to 10 8 g/mol;

polymerization type: particles obtained by emulsion or suspension polymerization or thermal degradation,

non-swellable.

3. The composition of claim 1 , comprising in addition an inorganic filler (D), the inorganic filler being characterized by the following feature: BET surface: from 50 to 400 m 2 /g.

4. The composition of claim 1 , the starter being selected from Lewis acids or Broensted acids or precursors of Lewis acids which can be activated by radiation to produce a Lewis acid.

5. The composition of claim 1 , the cationically hardenable compound (A) comprising a backbone containing moieties selected from polyether, polyesters, polyamides, polyurethanes, silicones and combinations thereof.

6. The composition of claim 1 , the aziridine moiety of compound (A) being characterized by the following formula

wherein

R represents H, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkinyl, C7-C15 alkylaryl, C7-C15 arylalkyl or C3-C12 cycloalkyl, and wherein hydrogen atoms can be replaced by C1 or F and/or wherein up to 5 carbon atoms may be replaced by atoms or group of atoms selected from O, CO, N or S,

E represents a C1-C18 branched or unbranched hydrocarbon chain wherein up to 5 carbon atoms can be replaced by atoms or group of atoms selected from O, CO, N or S, G represents a group selected from C(O)O, C(O)NR, C(O), C(O)C(O), C(O)(CH 2 ) m C(O) with m=1 to 10, C(S)NR or CH 2 ,

L represents O, S or NR, with x=0 or 1.

7. The composition of claim 1 , filler component (C) being present in an amount from 2 to 70 wt.-% with respect to the weight of the whole composition.

8. The composition of claim 3 , comprising the individual components in the following amounts:

cationically hardenable compound (A) comprising at least two aziridine moieties: from 5 to 90 wt.-%,

starter (B): from 0.25 to 50 wt.-%,

polymeric particles (C): from 2 to 70 wt.-%,

inorganic filler (D): from 1 to 80 wt.-%,

wt.-% with respect to the weight of the whole composition.

9. The composition of claim 1 , being characterized by at least one or all of the following parameters after hardening:

L* value: below 50%;

Tensile strength according to DIN 53504: at least 1.2 MPa;

Elongation at break according to DIN 53504: at least 100%;

Recovery from deformation according to ISO 4823: at least 90%;

Shore A hardness according to DIN 53505 after 24 h: below 70.

10. The composition of claim 3 , comprising:

the cationically hardenable compound (A) comprising at least two aziridine moieties and being present in an amount from 20 to 70 wt.-%,

the starter (B) being a Lewis or Broensted acid or precursor of a Lewis acid and being present in an amount from 1 to 25 wt.-%,

the polymeric particles (C) in an amount from 2 to 60 wt.-%,

inorganic filler (D) containing SiO2 particles in an amount from 5 to 50 wt.-%,

wt.-% with respect to the weight of the whole composition,

the polymeric particles having a maximum particle size of 150 μm or below and being composed of fluoropolymers comprising more than 99% monomer repeating units of tetra fluoro ethylene.

11. A kit of parts for preparing an elastomeric composition comprising

Part I and Part II,

Part I comprising a cationically hardenable compound (A) and polymeric particles (C),

Part II comprising a starter (B),

wherein inorganic filler (D) are either present in Part I or Part II or Part I and Part II, wherein the compound (A), the starter (B), the polymeric particles (C) and the inorganic filler (D) are of claim 3 .

12. A method of using the composition of claim 1 or the kit of parts according to claim 11 for producing a dental impression material or a dental retraction material.

13. The composition of claim 1 , wherein the scannability is enhanced, the hardness is reduced, or a combination thereof when in its hardened state.