The invention concerns a dental filling material with dual hardening mechanism, wherein i) a first hardening mechanism is based on a photocuring reaction, preferably a radical reaction, and ii) a second hardening mechanism is dependent on H.sub.2O as a reactant, especially as a ligand. Preferably, the second hardening mechanism is a gypsum-type reaction. Owing to the expansion of the composition an excellent marginal seal can be achieved, while the first hardening mechanism allows for a rapid cure on demand.