SUMMARY

Dental compositions typically comprise pigments to obtain the desired opacity (e.g. contrast ratio) and aesthetic shade. It has been found that the inclusion of pigments, especially titania, can hinder the depth of cure. Although various hardenable dental compositions have been described, industry would find advantage in compositions having improved properties such as a high depth of cure in combination with a high contrast ratio.

In one embodiment, a dental composition is described comprising a polymerizable resin comprising one or more ethylenically unsaturated monomers or oligomers and nanoparticles. The nanoparticles have a refractive index of at least 1.600 and an average discrete or aggregate particle size of no greater than 100 nm. The dental composition further comprises inorganic metal oxide filler having a discrete or aggregate average particle size of at least 200 nm. The nanoparticles are present at a concentration to provide a refractive index differential between the cured polymerizable resin inclusive of the nanoparticles and inorganic metal oxide filler such that the contrast ratio of the dental composition is at least 40.

In favored embodiments, the refractive index differential is balanced to maximize the contrast ratio, yet provide a depth of cure of at least 3.5 mm.

In another embodiment, a dental composition is described comprising a polymerizable resin comprising one or more ethylenically unsaturated monomers or oligomers wherein the polymerizable resin is substantially free of bisphenol-derived monomer. The polymerizable resin further comprises high refractive index nanoparticles as previously described. The concentration of components of the polymerizable resin and nanoparticles are selected such that the cured polymerizable resin inclusive of nanoparticles has a refractive index that differs from the (e.g. inorganic metal oxide) filler by at least 0.005, 0.006, 0.007, 0.008, 0.009, or 0.010.

In another embodiment, a dental composition is described comprising a polymerizable resin comprising at least one bisphenol-derived monomer and high refractive index nanoparticles (as just described). The concentration of components of the polymerizable resin and nanoparticles are selected such that the cured polymerizable resin inclusive of the nanoparticles has a refractive index that differs from the (e.g. inorganic metal oxide) filler by at least 0.010, 0.011, 0.012, 0.013, 0.014, or 0.015.

Also described are methods of treating a tooth surface, dental articles, and methods of making a dental composition.

