The invention describes a polymerisable mixture composition containing a liquid or semi-solid component A with at least one monomer portion and one, preferably powdery, solid component B on a polymethyl methacrylate (PMMA) base with a filler and/or additives, the liquid or semi-solid component A additionally having at least one oligomeric or polymeric compound modifying the monomer portion and which is miscible with the monomer portion. Furthermore, use of the mixture composition and a moulded part, for example a dental prosthesis, produced from the latter, is specified.