Dual-cure dental resins and adhesives with increased cure and color stability and low color

A hardenable composition comprising a light-curable component and a self-curable component, wherein said light-curable component comprises:

• an onium compound,
• a photosensitizer,
• and a resin system comprising a free radically active functional group and having no cationically active functional group, wherein said light-curable component is not miscible in water, and
• said self-curable component comprises a reducing agent and an oxidizing agent, wherein the reducing agent is selected from the group consisting of a urea reducing agent and a thiourea reducing agent,
• wherein the hardenable composition is formed by free radical polymerization of the resin system, and
• wherein the hardenable composition has an initial b* color value of less than 20 and a ΔE of less than 10, wherein ΔE represents the color change of the composition upon curing and is calculated using the equation ΔE=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2, and L* represents the lightness variable of the composition's color and a* and b* represent the chromatic characteristics of the composition's color in the CIE color system.