Comparison of diagnostic accuracy of film and digital tomograms for assessment of morphological changes in the TMJ

Objective: To compare diagnostic accuracy of tomograms obtained with film and three digital image receptor modalities for detection of morphological changes in the temporomandibular joint (TMJ). Methods: Lateral and frontal cross-sectional tomograms of 158 TMJs in 80 dry human skulls were obtained with four X-ray receptors: one conventional film (Agfa-Gevaert), two photostimulable phosphor (PSP) plates: VistaScan and Digora PCT and one charge-coupled device (CCD): ProMax. The film and the PSP plate tomograms were exposed in a Cranex Tome X-ray unit and the CCD tomograms in the ProMax X-ray unit. The tomograms were examined by three observers for the presence of morphological changes in the condyle, the mandibular fossa and the articular tubercle. Naked-eye inspection of the articular surfaces of the TMJs performed by the same three observers served as the gold standard for the true presence of morphological changes. Results: For examination of TMJ changes using lateral and frontal tomograms in combination and lateral tomograms separately, the ProMax modality obtained a significant lower diagnostic accuracy than the other three modalities, between which no significant differences were found. For morphological changes localized to the condyle in which the highest number of changes were present according to the gold standard, the same result was found. Conclusion: The ProMax modality was significantly less accurate than the film, VistaScan and Digora PCT modalities for the detection of overall TMJ morphological bone changes as well as condylar bone changes.