Abstract: Apparatus for obtaining extra- and/or intra-oral dental X-ray photographs comprising an X-ray tube having an anticathode with a plane target surface inclined with respect to the cathode-ray axis. The anticathode is disposed in a small tube within an X-ray-permeable protective sleeve. For changing the mode of operation from extra-oral to intra-oral, an adapter is fitted over the protective sleeve and actuates a change-over switch disposed within the housing of the X-ray tube. Regulating means control the intensity of the cathode-ray depending upon the position of the change-over switch for making either extra- or intra-oral photographs.