Intraoral storage phosphor radiography for approximal caries detection and effect of image magnification - Comparison with conventional radiography

Objectives. The aim of this study was first to test the newly developed storage phosphor (SP) system Digora for diagnostic accuracy of approximal caries detection with Special emphasis on image magnification compared with conventional radiography, and second, to test whether the image surroundings could have an influence on observer performance. Design. SP plates and Ektaspeed films were exposed simultaneously to 50 extracted premolars/molars, and the SP image files were transported to a different platform for processing. Ten observers rated 95 approximal surfaces for caries with four imaging modalities: (1) SP images at dental film size viewed with black surroundings, (2) magnified (x4) images viewed in the same manner, (3) magnified (x4) images viewed with text and graphics framing, and (1) films viewed on a light box. The observations were validated with microscopy. Diagnostic accuracy was calculated as the area beneath the receiver operating characteristic curve (A(z)). Results. No significant differences were found between SP images and films. Magnified SP images with text and graphics demonstrated significantly higher A(z) values than nonmagnified images both for enamel and dentin, and magnified images with black surroundings demonstrated similar results for dentin. Conclusions. In this in vitro material the observer performance for approximal caries detection with SP images was comparable to that with Ektaspeed films. The magnified SP images generally showed a significantly higher diagnostic accuracy than the nonmagnified SP images.