A comparison of a film-based and a direct digital dental radiographic system using a proximal caries model

Objectives: To compare the diagnostic accuracy of a dental radiographic film (Ektaspeed Plus) with the Sens-A-Ray direct digital imaging system using a proximal caries model. To study the effects of a scattering medium and compare the interpretations of dentists with dental students. Methods: We used 20 extracted premolar and molar teeth with 10 sound and 15 naturally carious surfaces, and prepared artificial cavities in the remaining 15 surfaces. Seven dentists and seven senior dental students reported the presence of lesions using a five point confidence scale. We analysed our data by Receiver Operating Characteristic (ROC) analysis and by obtaining sensitivities and specificities. Results: ROC areas showed no significant differences in the diagnostic accuracy achieved by dentists and dental students or by the addition of 20 mm of water as a scattering medium. A paler set of exposures produced significantly poorer diagnostic accuracy, but a darker set gave insignificant differences. Highly significant differences were found between the ROC areas for film and Sens-A-Ray and natural caries and artificial cavities, but the magnitudes of the differences were small. Sensitivities and specificities showed greater differences between methods and identified inferior interpretation of sound surfaces by students. Conclusions: Film was superior to Sens-A-Ray in the interpretation of proximal caries. The effects of a scattering medium were insignificant or trivial. Students were less reliable than dentists in the interpretation of sound surfaces but performed equally well with respect to natural caries and artificial cavities.