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 comprising:

1) a labile addition-fragmentation group; and

2) at least two surface-binding functional groups; and

c) optionally an inorganic oxide filler,

wherein the addition-fragmentation agent is of the formula:

wherein

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

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

Y is a surface-binding organic functional group;

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

wherein

Y-Q′ is selected from a monophosphate, a phosphonate group, a phosphonic acid group, a hydroxamic acid group, a carboxylic acid group, and acetoacetate group, an anhydride group, an isonitrile group, a silyl group, a disulfide group, a thiol group, an amino group, a sulfinic acid group, a sulfonic acid group, a phosphine group, a phenolic group or a heterocyclic aromatic group.

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

3. The dental composition of claim 1 wherein Q′ is an alkylene of the formula —C r H 2r —, where r is 1 to 10.

4. The dental composition of claim 1 wherein Q′ is a hydroxyl-substituted alkylene of the formula —CH 2 —CH(OH)—CH 2 —.

5. The dental composition of claim 1 wherein Q′ is an aryloxy-substituted alkylene, or an alkoxy-substituted alkylene.

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

7. The dental composition of claim 1 wherein the dental resin comprises an aromatic monomer having a refractive index of at least 1.50.

8. The dental composition of claim 1 wherein the dental resin is a low volume shrinkage resin.

9. 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.

10. The dental composition of claim 1 wherein the dental composition further comprises at least one other (meth)acrylate monomer is selected from the group consisting of 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. A method of treating a tooth surface, the method comprising

a) providing a curable dental resin of claim 1 ;

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

c) hardening the hardenable dental composition.

14. 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, relative to 100 parts by weight of a) and b),

said curable composition further comprising an initiator and;

<2% of stabilizers and pigments.

15. 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,

f) optionally 5-60 wt. % monomers having an acid-functional group; and

g) an initiator.

16. 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;

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

g) an initiator.

17. The curable dental composition of claim 1 further comprising a surface-modified inorganic filler of the formula:

where

Filler is an inorganic filler particle,

R 2 is Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group;

Q′ is a covalent bond or an organic (hetero)hydrocarbyl linking group having a valence of p+1;

Y′ is the residue of the surface-binding functional group Y;

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.

18. The curable dental composition of claim 17 wherein the Filler is silica.

19. The curable dental composition of claim 17 wherein the group Filler-Y′ p — is of the formula Silica-O—Si(R 7 ) 2 —

wherein each R 7 group is independently selected from the group of alkoxy, acetoxy, and halide.