Dental compositions and initiator systems with color-stable amine electron donors

1. A hardenable dental composition comprising:

a polymerizable component; and

an initiator system comprising at least one electron donor having the following formula:

wherein

N is nitrogen;

R1 is an alkyl group having 1 to 16 carbon atoms, or is CH 2 CH 2 X2;

R2, R3, R4, R5, R6, R7, R8 and R9 are independently selected from H or an alkyl group having 1 to 4 carbon atoms, with the proviso that at least one carbon atom at a position alpha to the nitrogen is bonded to at least one hydrogen atom;

X1 is selected from CO 2 R10, C(O)R11, C(O)R10, and CONR10R11 and X2 is selected from CN, CO 2 R10, C(O)R11, and C(O)R10, where each R10 and R11 are independently selected from H, alkyl groups having 1 to 6 carbon atoms, aryl groups, and aralkyl groups.

2. The composition of claim 1 , where in R1 is CH 3 , CH 2 -(lower alkyl), or CH 2 CH 2 X2;

R2 and R6 are independently H or CH 3 ;

R3 and R5 are H;

R4 is H, CH 3 or CH 2 - (lower alkyl); and

R7, R8, R9 and R10 are H.

3. The composition of claim 1 , wherein the electron donor has the following formula:

wherein R is an alkyl group having 1 to 4 carbon atoms.

4. The composition of claim 1 , wherein the electron donor has the following formula:

wherein R is an alkyl group having 1 to 4 carbon atoms.

5. The composition of claim 1 , wherein the polymerizable component comprises an ethylenically unsaturated component.

6. The composition of claim 5 , wherein the ethylenically unsaturated component comprises a meth(acrylate).

7. The composition of claim 1 , wherein the initiator system further comprises a visible light absorber.

8. The composition of claim 7 , wherein the visible light absorber comprises camphorquinone (CPQ).

9. The composition of claim 1 , wherein the initiator system further comprises an iodonium salt.

10. The composition of claim 9 , wherein the iodonium salt is diphenyliodonium hexafluorophosphate.

11. The composition of claim 1 , wherein the initiator system further comprises an second electron donor.

12. The composition of claim 11 , wherein the second electron donor comprises a polycyclic aromatic compound.

13. The composition of claim 12 , wherein the polycyclic aromatic component is selected from the group consisting of an anthracene derivative, a biphenylene derivative, and combinations thereof.

14. The composition of claim 1 , further comprising a filler.

15. The composition of claim 14 , wherein the filler comprises nanoparticles.

16. The composition of claim 1 , wherein the composition is substantially free of UV stabilizers.

17. The composition of claim 1 , wherein the composition has natural tooth fluorescence.

18. A photoinitiator system comprising:

a visible light absorber;

an iodonium salt; and

at least one electron donor having the following formula:

wherein

N is nitrogen;

R1 is an alkyl group having 1 to 16 carbon atoms, or is —CH 2 —CH 2 X2;

R2, R3, R4, R5, R6, R7, R8, and R9 are independently selected from H or an alkyl group having 1 to 4 carbon atoms, with the proviso that at least one carbon atom at a position alpha to the nitrogen is bonded to at least one hydrogen atom;

X1 is selected from CO 2 R10, C(O)R11, C(O)R10, and CONR10R11 and X2 is selected from CN, CO 2 R10, C(O)R11, and C(O)R10, where each R10 and R11 are independently selected from H, alkyl groups having 1 to 6 carbon atoms, aryl groups, and aralkyl groups.

19. The photoinitiator system of claim 18 , wherein the electron donor has the following formula:

wherein R is an alkyl group having 1 to 4 carbon atoms.

20. The photoinitiator system of claim 18 , wherein the electron donor has the following formula:

wherein R is an alkyl group having 1 to 4 carbon atoms.

21. The photoinitiator system of claim 18 , wherein the visible light absorber comprises camphorquinone (CPQ).

22. The photoinitiator system of claim 18 , wherein the iodonium salt comprises diphenyliodonium hexafluorophosphate.

23. The photoinitiator system of claim 18 , wherein the photoinitiator system further comprises a second electron donor.

24. The photoinitiator system of claim 23 , wherein the second electron donor comprises a polycyclic aromatic compound.

25. The photoinitiator system of claim 24 , wherein the polycyclic aromatic component is selected from the group consisting of an anthracene derivative, a biphenylene derivative, and combinations thereof.

26. A hardenable composition comprising a polymerizable component and a photoinitiator system of claim 18 .

27. A dental article made by polymerizing the composition of claim 1 .