Dental compositions comprising nanoparticles providing a refractive index differential between polymerizable resin and filler

1. A dental composition comprising:

a polymerizable resin comprising:

a homogenous organic phase comprising:

one or more addition-fragmentation material represented by Formulae I:

wherein:

R 1 , R 2 , and R 3 are independently Z—Y—, a (hetero)alkyl group, or a (hetero)aryl group, with the proviso that at least one of R 1 , R 2 and R 3 is Z—Y—,

each X 1 is independently —O— or —NR 4 —,

each Z is independently

each Y is independently —R 5 —, —C(O)—O—R 6 —, —C(O)—NR 4 —R 6 —, —R 6 —C(O)—O—R 6 —, —O—R 6 —, —S—R 6 —, —NR 4 —R 6 —, —SO 2 —R 6 —, —C(O)—R 6 —, —OC(O)—R 6 —, or —NR 4 —C(O)—R 6 —,

each R 4 is independently —H or C 1-4 alkyl,

each R 5 is independently C 1-10 alkylene optionally substituted with hydroxyl or alkoxy,

each R 6 is independently C 1-6 alkylene, 5- or 6-membered cycloalkylene, or

C 6-16 arylene,

n is 0 or 1,

one or more low shrinkage monomer represented by the Formulae II:

wherein:

each G is independently selected from:

each Q is independently hydrogen, methyl, phenyl, and phenoxymethyl,

U is selected from:

each of a, b, c, and d is an integer independently selected from 0-3, wherein a+b=1-6, and c+d=1-6, and

one or more low viscosity polymerizable diluent characterized by a viscosity of no greater than 300 Pa*s, and

nanoparticles having a refractive index of at least 1.600 and an average discrete or aggregate particle size of no greater than 100 nm; and

inorganic metal oxide filler characterized by a discrete or aggregate average particle size of at least 200 nm;

wherein the nanoparticles are present at a concentration to provide a refractive index differential between the polymerizable resin in a cured state and the inorganic metal oxide filler such that the contrast ratio of the dental composition is at least 40.

2. A method of treating a tooth surface, the method comprising:

providing a dental composition according to claim 1 ;

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

curing the polymerizable resin thereby hardening the dental composition.

3. A dental article comprising the dental composition of claim 1 , wherein the dental composition is at least partially hardened.

4. The dental composition of claim 1 , the addition-fragmentation material represented by Formula Ia:

5. The dental composition of claim 1 , the one or more addition-fragmentation material present in the dental composition in an amount of no greater than 2 wt %.

6. The dental composition of claim 1 , the one or more low shrinkage monomer being present within the homogenous organic phase in an amount of 50-70 wt %.

7. The dental composition of claim 1 , the one or more low shrinkage monomer being present within the dental composition in an amount 15-20 wt %.

8. The dental composition of claim 1 , one or more low shrinkage monomer represented by Formulae IIa:

9. The dental composition of claim 8 , wherein each G is

10. The dental composition of claim 1 , comprising a low shrinkage monomer represented by formula IIb:

11. The dental composition of claim 10 , the low shrinkage monomer of Formula III being present within the homogenous organic phase in an amount of 50-70 wt %.

12. The dental composition of claim 10 , the low shrinkage monomer of Formula III being present within the dental composition in an amount of 15-20 wt %.

13. The dental composition of claim 1 , the one or more low viscosity polymerizable diluent present in the dental composition in an amount of 2-10 wt %.

14. The dental composition of claim 1 , the one or more low viscosity polymerizable diluent selected from 1,12-dodecanediol dimethacrylate (DDDMA), urethane dimethacrylate (UDMA), triethylene glycol dimethacrylate (TEGDMA), glycerol dimethacrylate (GDMA), ethyleneglycol dimethacrylate, neopentylglycol dimethacrylate (NPGDMA), polyethyleneglycol dimethacrylate (PEGDMA), and a combination thereof.

15. The dental composition of claim 1 , comprising low viscosity polymerizable diluents of formula III and formula IV:

16. The dental composition of claim 1 , one or more of:

the nanoparticles comprising silica nanoparticles, zirconia nanoparticles, or a combination thereof, and

the inorganic metal oxide filler comprising silica particles, zirconia particles, or a combination thereof.

17. The dental composition of claim 16 , the silica nanoparticles present in the dental composition in an amount no greater than 5 wt %, and the silica nanoparticles and the zirconia nanoparticles present in a weight ratio of 1:1 to 1:10.

18. The dental composition of claim 1 , the inorganic metal oxide filler being present in the dental composition in an amount of 60-70 wt %.

19. The dental composition of claim 1 , the inorganic metal oxide filler comprising silica particles, zirconia particles, or a combination thereof.

20. The dental composition of claim 1 , further comprising one or more:

a photoinitiator system,

one or more pigment, and

yitterbium fluoride.