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Visually detectable resolution of intraoral dental films
A Künzel1, D Scherkowski, R Willers
1Department of Oral Surgery, Faculty of Dentistry, Heinrich Heine University Düsseldorf, Moorenstrasse 5, 40225 Düsseldorf, Germany. kuenzel@uni-duesseldorf.de
Objectives:
The visually utilizable resolution of intraoral dental films was examined with the naked eye, with two-fold optical magnification and after digitization using a computer display.
Methods:
Agfa Dentus M2, Kodak Ektaspeed Plus and Kodak InSight dental films were exposed with a line pair (lp) test pattern providing frequencies up to 16.6 lp mm(-1). Films were developed at 24 degrees C in a Dürr Periomat machine and at 28 degrees C in a Dürr AC245 machine. Forty dental students evaluated the maximum visually detectable resolution with their naked eye, with an X-ray viewer (providing two-fold magnifying lenses and eliminating disturbing light) and following digitization and monitor display examination.
Results:
The best detectable resolution was achieved through digitization, reaching a mean of up to 16.5 lp mm(-1). With two-fold magnification, a mean of up to 13.3 lp mm(-1) could be resolved, while only 11.7 lp mm(-1)could be resolved with the naked eye. Unlike the other film types, the resolution of Ektaspeed depended on the processing type when viewing digitized images or when viewing with the naked eye. There was a trend for students above 29 years of age to detect a lower resolution with the naked eye, although they performed comparably with students below 29 years when using the X-ray viewer or viewing digitized images.
Conclusions:
Film resolution is utilized best through digitization and secondly using a magnifying lens. With the naked eye, a mean of 11 lp mm(-1) with a broad distribution can be resolved. A magnifying lens is recommended if resolution is important or if the viewer's eyesight is reduced. Compared with E-speed films, Kodak Insight was less dependent on processing conditions.