A dental adhesive composition is described comprising a photocurable ionomer, radiopaque metal oxide nanoparticles, a phosphorous-containing acidic monomer, other polymerizable resin components, and a polar solvent. In a favored embodiment, the adhesive composition comprises a photocurable ionomer in an amount up to 15 wt-%； 5 wt-% to 30 wt-% of radiopaque metal oxide nanoparticles that comprise a basic surface (such as zirconia) wherein the nanoparticles comprise an organosilane surface treatment； a phosphorous-containing acidic monomer in an amount up to 10 wt-%； and 10 wt-% to 50 wt-% of solvent comprising water and at least one alcohol, ketone, or mixture thereof.
