Abstract: An apparatus for making a mold for forming positive models identical to a positive master has upper and lower mold shells having confronting and contiguous rims lying in respective planes. The shells are dimensioned when juxtaposed to spacedly contain the master. A clamp is engageable with the shells generally at the rims to hold the shells together with the plane of their rims spaced apart.

Abstract: A method of making a dental prosthesis by forming a model of a tooth stump, coating with a layer of electrically conductive material, galvanically plating over the conductive material with a layer of copper, exposing occlusal surfaces of the model, coating the exposed occlusal surfaces of the model with an electrically conductive material followed by a galvanic plating on the model occlusal surfaces, and separating the copper layers form each other at about the tooth equator into an occlusal mold/electrode and a stump mold/electrode. The electrodes are used in a spark erosion process to form a dental prosthesis from a solid matrix body.

Abstract: A method of inspecting a positive dental model having an impression plane comprises the step of first projecting a small beam of light of predetermined cross section on individual teeth of the model generally perpendicular to the impression plane, that is the plane perpendicular to which the impression fork was fitted to and removed from the patient's jaw. Thus the beam forms on each tooth a spot having a shape dependent on the contours of the respective tooth and the inclination of the respective tooth surface to the beam. The spot is moved from tooth to tooth on the model and the shapes of the spots of the beam on adjacent teeth are compared. If the shape changes, the teeth are not parallel and if there is a shadow or interruption of the teeth there is an undercut, and both conditions have to be corrected by regrinding the patient's tooth stumps. Similarly as the spot is moved, it can be used to measure the height and width of the teeth, the space between them, and even the overall arch length.