Abstract: Apparatus for smoothing, cutting, grinding and polishing with a disc, comprise a disc drive having a head including a disc retainer member insertable for formfitting interlock into an oblong central hole of the disc. The head is undercut by grooves cooperating with the disc and delimiting means forming a bayonet-type interlock for rotation in a first sense as well as for rotation in an opposite second sense.

Abstract: A device (1) for holding X-ray film (2) during the taking of radiographs of patients' teeth with X-rays emanating from a cone (13) of an X-ray source has a bite wing (3) extending in a horizontal center plane perpendicularly to an X-ray film plane, for retention of the device by patients' teeth. An X-ray film holder is carried by the bite wing for retaining X-ray film centered relative to the horizontal center plane and alternatively vertically offset from that horizontal center plane. A guide rod (5) is connected laterally to the bite wing and extends in the horizontal center plane perpendicularly away from the X-ray plane, for guidance of X-ray cone. An aiming rod (7) extends in a vertical center plane of the centered and the vertically offset X-ray film. A transverse rod (6) extends in the horizontal center plane from the guide rod to the aiming rod, for mounting that aiming rod (7) at a distance from the bite wing.

Abstract: Honing and polishing instrument especially intended for dental use and being provided with a rotatable shaft. A replaceable honing or polishing unit made of a flexible elastic material can be attached to the free end of the shaft. An undercut indent in the unit embraces a radial sleeve at the free end of the shaft. The shaft also has an end portion extending axially beyond the sleeve which is inserted in a corresponding bore at the bottom of the indent in the unit.