Performance of a photostimulable storage phosphor digital system with or without the sharpen filter and cone beam CT for detecting approximal enamel subsurface demineralization

Objectives: The aim of this study was to assess the performance of photostimulable storage phosphor (PSP) radiographs with or without using the sharpen filter and cone beam CT (CBCT) for detecting enamel subsurface demineralization. Methods: Enamel subsurface demineralization was induced on one of the approximal surfaces of 120 sound human teeth. Standardized images of all teeth were acquired after the demineralization phase using the Digora (R) Optime (Orion Corp./Soredex, Helsinki, Finland) (PSP) and the i-CAT (TM) (Imaging Sciences International, Hatfield, PA) (CBCT) systems. Three calibrated observers interpreted the images using a five-point scale (1, demineralization definitely absent; 2, demineralization probably absent; 3, unsure; 4, demineralization probably present; and 5, demineralization definitely present). Diagnoses were validated by cross-sectional microhardness profiling in the test areas of the approximal surfaces. Interobserver agreement was analysed using kappa statistics. Accuracy was estimated by the areas under the receiver operating characteristic curves (4,), which were compared using the Kruskal Wallis test (alpha = 5%). Results: Interobserver agreement was higher for CBCT (kappa = 0.7-0.8), followed by sharpen-filtered (kappa = 0.6-0.7) and original (kappa = 0.5-0.6) images. CBCT presented the highest accuracy value (A(z) = 0.897) compared with the original (A(z) = 0.792) and sharpen-filtered (A(z) = 0.712) images. However, no statistical differences were observed between the imaging modalities (p = 0.0794). Conclusions: It can be concluded that PSP radiographs with or without using the sharpen filter and the CBCT images may be useful adjuncts for detecting subtle approximal enamel demineralization.