Mechanically induced images on dental x-ray film

The appearance on processed x-ray film of images due to mechanical manipulation (bending, pressure, biting, etc.), as well as the influence of a number of other factors (degree and direction of bending, protective effect of film packet, etc.), was studied. A variety of very dissimilar images was produced. Some appeared as plus density artifacts, others as minus density artifacts. A critical influence on the nature of the image was observed with manipulation of film that was unexposed or was exposed before or after manipulation. The emulsions on the two sides of the film base responded differently to different types of manipulation. Forces exerted on the unprotected film (in the darkroom) induced images different than corresponding forces exerted through the film packet.