Accuracy of radiographic caries diagnosis at different kilovoltages and two film speeds.

Different kilovoltages (50, 60, 70, 90) and two films differing in speed (Kodak Ultra-Speed and Ektaspeed) were examined with regard to the diagnostic accuracy at detection of dental caries. Ten observers graded the occurrence of caries in radiographs of extracted premolars and their findings were compared with the actual presence or absence of caries. The ROC-technique was used to evaluate the results using the area under the curve as a measure of diagnostic accuracy. A significant difference was found between kilovoltages with better diagnostic accuracy for the lower kilovoltages. No significant difference was found between the two types of film. Our results suggest that a kilovoltage of 60 offers a proper balance between absorbed radiation dose and diagnostic accuracy. The use of Kodak Ektaspeed offers a diagnostic accuracy similar to that of Kodak Ultra-Speed.