Abstract: A permanent magnet assembly for stably fixing a denture comprising a permanent magnet, a casing made of a corrosion-resistant, magnetic material having a cavity for receiving the permanent magnet, and a seal plate for covering an opening of the casing to prevent the permanent magnet from exposing outside, the seal plate consisting of a seal ring member made of a corrosion-resistant, non-magnetic material and a disc plate made of a corrosion-resistant, soft-magnetic material and having substantially the same outer diameter as the inner diameter of the seal ring member, the seal ring member and the disc plate being concentrically arranged in the same plane, the disc plate being welded to the seal ring member in their abutment, and the seal ring member being welded to the casing. Laser welding is utilized.

Abstract: An artificial tooth for anterior teeth portions including a concave hollow extending from a basal segment to a lingual incisal segment and located in a substantially central segment, wherein: a percentage of the major diameter of the hollow to the full length is in a range of 10% to 100%, a maximum depth of the hollow is in a range of 0.5 mm to 5.0 mm and a minimum thickness of a cervical segment is in a range of 0.1 mm to 5.0 mm, and a width and length of the cervical segment being defined in terms of a percentage of the cervical minimum mesiodistal length to the maximum mediodistal length being in a range of 50% to 100% and a percentage of the cervical major diameter to the full major diameter being in a range of 10% to 50%.

Abstract: An artificial tooth has a length of its buccal side substantially equal to that of a natural tooth and a length of its lingual side in the range of 4.0 mm to a length shorter than the length of its buccal side by at least 2.5 mm. A basal surface is of a concave shape in engagement with a more convex shape than the shape in cross-section of the alveolar ridge. One or two proximal surfaces of the basal surface is or are provided at the substantial center with an occlusally inclined smooth groove having a width of 1.5 to 5.0 mm, a maximum depth of 0.5 to 3.0 mm, and an proximal upper end located away from the highest position. The occlusal surface has a mesiodistal length substantially equal to that of a natural tooth and a W.sub.2 /W.sub.1 ratio falling in the range of 55 to 95% of that of a natural tooth, wherein W.sub.1 is the mesiodistal length and W.sub.2 is the buccolingual length.

Abstract: An improved device for measuring an inclination angle of the tapered surface of a plaster die duplicated from the prepared tooth in the field of restorative dentistry is disclosed. The device is used also for scraping operation for the was pattern. It includes a turnable tool holding plate which is turnably held in a slot formed on the lower part of a core so as to turn about a support shaft. A rotary ring with its lower end face cut to a predetermined inclination angle, for instance, 7 degrees is rotatably fitted onto the core in such a manner that the lower inclined face comes in contact with the upper faces of wing-shaped lateral projections of the tool holding plate with a transversely extending shaft disposed therebetween. The transversely extending shaft is inserted through the tool holding plate at the same inclination angle as that of the lower inclined end face of the rotary ring so that its axis intersects with the axis of the support shaft.