A method for producing a guide rail which is provided for guiding a mobile milling head (2, 12, 14) or cutting tool during the machining of prefabricated prosthetic teeth, wherein the method is characterized by the following steps: A) Generating or Providing a virtual 3D model of a dental prosthesis (16, 18) with a virtual model of a prosthesis base (26, 28) as a gum imitation and with at least one virtual model of at least one machined prosthetic tooth (20, 24) to be arranged in the prosthesis base (26, 28) to reproduce at least one tooth; B) Calculating a volume to be removed from at least one prefabricated prosthetic tooth by comparing the at least one virtual model of the at least one machined prosthetic tooth (20, 24) with at least one virtual model of the at least one prefabricated prosthetic tooth using a CAD method; C) Generating a virtual model of a guide rail using a CAD method, which guide rail is fixed or fixable to a mount for fastening the at least one prefabricated prosthetic tooth, wherein the guide rail is modeled such and the mount is positioned relative to the guide rail such and the at least one prefabricated prosthetic tooth is fastened in the mount in an orientation such that the guide rail enables guidance of at least one milling head (2, 12, 14) and/or at least one cutting tool of known dimensions, in such a manner that the volume to be removed from the at least one prefabricated prosthetic tooth is traversed with the at least one milling head (2, 12, 14) and/or the volume to be removed from the at least one prefabricated prosthetic tooth is cut away with the at least one cutting tool; and D) Producing a physical guide rail on the basis of the virtual model of the guide rail using a CAM method. A) Generating or Providing a virtual 3D model of a dental prosthesis (16, 18) with a virtual model of a prosthesis base (26, 28) as a gum imitation and with at least one virtual model of at least one machined prosthetic tooth (20, 24) to be arranged in the prosthesis base (26, 28) to reproduce at least one tooth; B) Calculating a volume to be removed from at least one prefabricated prosthetic tooth by comparing the at least one virtual model of the at least one machined prosthetic tooth (20, 24) with at least one virtual model of the at least one prefabricated prosthetic tooth using a CAD method; C) Generating a virtual model of a guide rail using a CAD method, which guide rail is fixed or fixable to a mount for fastening the at least one prefabricated prosthetic tooth, wherein the guide rail is modeled such and the mount is positioned relative to the guide rail such and the at least one prefabricated prosthetic tooth is fastened in the mount in an orientation such that the guide rail enables guidance of at least one milling head (2, 12, 14) and/or at least one cutting tool of known dimensions, in such a manner that the volume to be removed from the at least one prefabricated prosthetic tooth is traversed with the at least one milling head (2, 12, 14) and/or the volume to be removed from the at least one prefabricated prosthetic tooth is cut away with the at least one cutting tool; and D) Producing a physical guide rail on the basis of the virtual model of the guide rail using a CAM method.