Detection of proximal caries in conventional and digital radiographs: an in vitro study

Abstract

Objectives: To compare digital images to conventional film radiography in the diagnosis of proximal caries.

Methods: Fifty-one molars and 24 premolars were studied and divided in groups of three teeth. They were fixed in silicone and radiographed using InSight film (Kodak) and the digital systems Digora (Soredex), DenOptix (Gendex) and CygnusRay MPS (Progeny). Twenty-five radiographs were obtained in each modality and four proximal surfaces were analyzed in each radiograph. Radiographs were interpreted individually by one observer at three different sessions for each imaging modality. Caries lesions were classified according to their depth: (0) absent; (1) restricted to enamel; (2) reaching the dentino-enamel junction; and (3) reaching the dentin. The teeth were sectioned and ground in order to obtain the gold standard and were examined histologically by stereomicroscopy.

Results: The Kendall test was employed and showed a good intra-observer agreement among the three evaluations implemented. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were all calculated, and there were no significant differences observed among the four imaging modalities studied (ANOVA, p< or =0.05). Besides, the ROC curve was determined for each modality and no statistically significant differences were observed when comparing the areas under the ROC curve at the 5% level of significance.

Conclusions: The results demonstrate that the diagnostic accuracy of digital images is similar to that of conventional film radiography in the detection of proximal caries.