Accuracy in radiographic diagnosis: Dutch practitioners and dental caries

The effective diagnostic accuracy of dentists is the missing link in models for calculating the optimal frequency for radiographic recall. The purpose of this study was to describe the accuracy of Dutch general dental practitioners using bitewing radiographs for the diagnosis and treatment of approximal caries in dentine. Practitioners from a 10 per cent (n = 444) national random sample were sent a set of simulated bitewings, a patient description and a diagnostic response form. The radiographs showed tooth surfaces with (n = 45) and without (n = 60) dentine caries. Microradiography of the sectioned teeth was used as a diagnostic reference standard. The participants were asked to diagnose dentine caries using a five-point certainty scale and decide if restorative treatment was indicated. The response was 62 per cent (n = 276). The area under a mean receiver operating characteristic curve for the practitioners was 88 per cent of the area representing optimal accuracy. Diagnostic accuracy, however, varied considerably between dentists. For caries considered to be 'probably' in the dentine mean sensitivity was 54 per cent (s.d. 14 per cent) and specificity was 97 per cent (s.d. 5 per cent). The pooled restorative treatment decisions of the dentists had a mean sensitivity of 62 per cent and a specificity of 96 per cent. More surfaces were considered in need of treatment than were diagnosed as 'probably' having dentine caries. Treatment decisions were more accurate than diagnostic ability might indicate. Paradoxically this may be because errors in visual ability were partly compensated for by 'over treatment' decisions.