Diagnosis of Approximal Caries after Delayed Scanning of Photostimulable Phosphor Plates

Considering the high diagnostic accuracy and wide dynamic range of photostimulable phosphor plates (PSPs), they can be a good alternative for radiographic films. This study was aimed to assess the effects of delay in scanning PSPs on the diagnostic accuracy of detection of approximal caries. Radiographs from fifty-two extracted molar and premolar teeth were radiographed using DIGORA PSP (Soredex Corporation, Helsinki, Finland). The teeth were either intact or with non-cavitated approximal caries. The plates were scanned immediately (time zero) and at 10 min, 30 min, 60 min and 120 min after exposure. Sixty-five images were obtained and evaluated for presence or absence of approximal caries by two oral and maxillofacial radiologists and 2 restorative specialists. The diagnostic accuracy of approximal caries detection was measured using a 5-point rating scale. Definite presence of caries was confirmed using a stereomicroscope. Analysis of caries detection data was performed by calculating sensitivity and specificity using repeated measures with ANOVA. Significant differences were found in complete negative predictive value, absolute negative predictive value and complete dentine sensitivity value between different scan times ( < 0.05). These values were significantly different at 10 min, 60 min and 120 min ( < 0.05). However, immediate scan and 30 min delay were not significantly different ( > 0.05). The accuracy of approximal caries detection at 120 min was less than at 60 min and at 60 min was less than at 30 min. In order to detect approximal caries more accurately, DIGORA PSPs should be scanned within 30 min after exposure.