A method for making a cast of a tooth using a curable dental impression compound containing a ferromagnetic compound, preferably an iron powder additive as well as a method for guiding the compound into the sub-gingival areas of the tooth by the use of a magnetic field. The term “ferromagnetic” as used herein is used to describe a substance that is capable of being attracted by a magnetic field, in particular a substance that exhibits a high degree of magnetic permeability.