2003 Volume 28 Issue 1 Pages 27-36
The COMMCAT IS-2000TM (Imaging Sciences International, Hatfield, PA, USA) is a tomographic machine for scanning the dentomaxillofacial region and is capable of imaging the sagittal and coronal sections of the temporomandibular joint (TMJ). The feasibility and accuracy of tomography for the TMJ were examined by use of the COMMCAT IS-2000TM and four dried human skulls with radiopaque steel markers. To assess the setting accuracy of the slice position, a steel marker was fixed at the center of the superior surface of the condyle, and images of five sagittal sections were taken, i.e., directly above the marker and 1 mm and 2 mm distance from it in both the medial and distal planes. The deviation of the slice position was found to be within ± 1 mm for all test subjects. To evaluate the dimensional accuracy of this method, the difference between the actual value and the graphically observed value with respect to the tomographic image of the condyle was examined using a digital caliper. The difference between values for the anteroposterior distance was 0.43 mm and that for the mediolateral distance was 0.52 mm. The effect of the difference in tomographic motion and slice thickness on the image quality was then evaluated. Under identical exposure conditions, hypocycloidal tube motion and the slice thickness of 1 mm produced the best image quality because blurring of the image and the degree of superimposition of the surrounding structures were minimal. These results suggest that the COMMCAT IS-2000TM is a high-quality diagnostic tool for visualizing the bone structure of the TMJ.
