Dental compositions comprising addition-fragmentation agents

1. A curable dental composition comprising:

a) at least one dental resin comprising at least two ethylenically unsaturated groups;

b) an addition-fragmentation agent of the formula:

wherein

R 1 , R 2 and R 3 are each independently Z m -Q-, Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least one of the R 1 , R 2 and R 3 is Z m -Q-, and with the proviso that at least one of the R 1 , R 2 and R 3 is Y p -Q′-

Q is a covalent bond or a linking group, having a valence of m+1;

Q′ is a covalent bond or a linking group, having a valence of p+1;

Z is an ethylenically unsaturated polymerizable group,

Y is a functional group that bonds to, or etches a dental structure on which the addition-fragmentation agent is disposed;

m is 1 to 6;

p is 1 or 2;

each X 1 is independently —O— or —NR 4 —, where R 4 is H or C 1 -C 4 alkyl, and

n is 0 or 1; and

c) optionally an inorganic oxide filler.

2. The dental composition of claim 1 wherein at least on of R 1 , R 2 and R 3 of the addition-fragmentation agent contain both Z m -Q- and Y p -Q′-, where

Q is a covalent bond or a linking group, having a valence of m+1;

Q′ is a covalent bond or a linking group, having a valence of p+1;

Z is an ethylenically unsaturated polymerizable group,

m is 1 to 6;

p is 1 or 2; and

Y is a functional group that bonds to, or etches a dental structure on which the addition-fragmentation agent is disposed.

3. The dental composition of claim 2 wherein Z of the addition-fragmentation agent comprises a vinyl, vinyloxy, (meth)acryloxy, (meth)acrylamido, styrenic and acetylenic functional groups.

4. The dental composition of claim 1 wherein Q is selected from —O—, —S—, —NR 4 —, —SO 2 —, —PO 2 —, —CO—, —OCO—, —R 6 —, —NR 4 —CO—NR 4 —, —NR 4 —CO—O—, —NR 4 —CO—NR 4 —CO—O—R 6 —, —CO—NR 4 —R 6 —,—R 6 —CO—O—R 6 —, —O—R 6 —S—R 6 —, —NR 4 —R 6 —,—SO 2 —R 6 —, —PO 2 —R 6 —,—CO—R 6 —, —OCO—R 6 —, —NR 4 —CO—R 6 —, —NR 4 —R 6 —CO—O—, and —NR 4 —CO—NR 4 —,

wherein each R 4 is hydrogen, a C 1 to C 4 alkyl group, or aryl group, each R 6 is an alkylene group having 1 to 6 carbon atoms, a 5- or 6-membered cycloalkylene group having 5 to 10 carbon atoms, or a divalent arylene group having 6 to 16 carbon atoms, with the proviso that Q-Z does not contain peroxidic linkages.

5. The dental composition of claim 1 wherein Q and/or Q′ is an alkylene.

6. The dental composition of claim 1 wherein Q and/or Q′ is a hydroxyl-substituted alkylene.

7. The dental composition of claim 1 wherein the ethylenically unsaturated groups of the dental resin are (meth)acrylate groups.

8. The dental composition of claim 1 wherein the dental resin is an isocyanurate resin, a tricyclodecane resin, cyclic allylic sulfide resins; methylene dithiepane silane resins; and poly(meth)acryloyl-containing resins, or mixtures thereof.

9. The dental composition of claim 1 wherein the hardened dental composition exhibits a stress deflection no greater than 0.6.

10. The dental composition of claim 1 wherein the dental composition further comprises at least one other (meth)acrylate monomer is selected from ethoxylated bisphenol A dimethacrylate, 2-hydroxyethyl methacrylate, bisphenol A diglycidyl dimethacrylate, urethane dimethacrylate, triethlyene glycol dimethacrylate, glycerol dimethacrylate , ethylenegylcol dimethacrylate, neopentylglycol dimethacrylate (NPGDMA), polyethyleneglycol dimethacrylate, and mixtures thereof.

11. The dental composition of claim 1 wherein the inorganic oxide filler comprises nanoparticles.

12. The dental composition of claim 1 comprising a surface modified inorganic oxide filler.

13. The curable dental composition of claim 12 comprising a surface-modified inorganic oxide filler of the formula:

where

Filler is an inorganic oxide filler particle,

R 2 and R 3 are each independently Z m -Q-, Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group;

Q is a covalent bond or a linking group, having a valence of m +1;

Q′ is a covalent bond or an or a linking group, having a valence of p +1;

Z is an ethylenically unsaturated polymerizable group,

Y′ is the residue of the functional group Y;

m is 1 to 6;

p is 1 or 2;

X 1 is independently —O- or —NR 4 —, where R 4 is H or C 1 -C 4 alkyl, and

n is 0 or 1.

14. A method of treating a tooth surface, the method comprising

a) providing a curable dental composition of claim 1 ;

b) placing the dental composition on a tooth surface in the mouth of a subject; and

c) curing the curable dental composition.

15. The curable dental composition of claim 1 comprising a universal dental restorative comprising:

a) 15-30 wt % of a curable dental resin comprising at least two polymerizable, ethylenically unsaturated groups;

b) 70-85 wt % of an inorganic filler;

c) 0.1 to 10 parts by weight of the addition-fragmentation agent of claim 1 , relative to 100 parts by weight of a) and b),

said curable composition further comprising an initiator and;

<2%, stabilizers, or pigments.

16. The curable dental composition of claim 1 comprising a flowable restorative composite comprising:

a) 25-50 wt % of a curable dental resin comprising at least two polymerizable, ethylenically unsaturated groups;

b) 50-75 wt % of an inorganic filler;

c) 0.1 to 10 parts by weight of the addition-fragmentation agent, relative to 100 parts by weight of a) and b);

d) an initiator;

e) <2% stabilizers and pigments, and

f) optionally 5-60 wt. %% monomers having a acid- functional group.

17. The curable dental composition of claim 1 comprising a resin-modified glass-ionomer adhesive comprising:

a) 10-25 wt. % of a partially (meth)acrylated poly(meth) acrylic acid;

b) 5-20% of a hydroxyalkyl (meth)acrylate;

c) 30-60% of fluoroaluminosilicate (FAS) acid reactive glass;

d) 0-20% non-acid reactive fillers;

e) 10-20% water; and

f) 0.1 to 10 wt. % of the addition-fragmentation agent, relative to 100 parts by weight of a) and b).

18. The curable dental composition of claim 1 comprising a dental adhesive comprising:

a) 30-8-wt. % mono (meth)acrylate) monomers;

b) 1-10 wt. % polyfunctional (meth)acrylate monomers;

c) 5-60 wt. % monomers having a acid- functional group;

d) 0-10, poly(meth)acrylic acid methacrylate monomers;

e) 0.1 to 10 wt. % of the addition-fragmentation agent, relative to 100 parts by weight of a) to d);

f) an initiator,

g) 0-30% inorganic filler, relative to 100 parts by weight of a) to d);

h) 0 to 25 wt. % solvent relative to 100 parts by weight of a) to d);

i) 0 to 25 wt. % water relative to 100 parts by weight of a) to d); and

<2% stabilizers and pigments.