In vitro comparison between the image obtained using PSP plates and Kodak E-speed films. 
The aim of this study was to compare the intra-oral radiographic images obtained by a PSP digital radiography system ("Orex", Israel) with that obtained using Kodak Ultra speed films in terms of image quality, radiation dosage and diagnostic value.  The physical measurement of image quality was conducted with an aluminum step-wedge.  Radiation dosage was measured with a dosimeter.  Fog and base levels were measured by developing unexposed films and scanning unexposed PSP plates.  The in vitro model included preparation and radiographic evaluation of approximal artificial lesions in premolars and molars in depths ranging from 0.25 mm to 1.00 mm.  Radiographs were evaluated for the existence of a lesion and its size by 8 experienced clinicians.  Relative contrast was similar in both methods.  The resolving power of the digital system was lower than that of the E-speed film.  As for the subjective evaluation of artificial lesions, there was no significant difference between the two methods excluding those tooth images without lesions, where the analog method was found to be more accurate.  The PSP system ("Orex") provides good image quality and diagnostic information with reduced exposure when compared with E-speed film.