Process for preparating dental prosthesis

To prepare a dental prosthesis that has a shape exactly the same as in the form at the time of sound state, with superior intra-oral fitness precision, a process for preparing a dental prosthesis utilizing a CAD/CAM system includes subjecting three-dimensional coordinate information of an intra-oral shape measured by impression taking or by photographing within an oral cavity of a patient, to three-dimensional graphic display on a graphic display device and designing a dental prosthesis on the three-dimensional graphic, wherein three-dimensional coordinate information of a previously preserved intra-oral shape of a patient at the time of sound state is subjected to graphic display simultaneously on the graphic display device; the dental prosthesis of an objective tooth is designed so as to have a shape same as the shape at the time of sound state; the obtained design data of the dental prosthesis is transmitted to a milling processor as a processing command; and a block material is subjected to milling processing to prepare a dental prosthesis.