1996 Volume 2 Issue 2 Pages 141-149
The purpose of this study was to determine an optimal projection method in order to obtain reformatted sagittal CT images (CT) for condylar position measurements and to estimate the accuracy of the measurements.
Three human dried skulls (6TMJs) were employed in this study. The reformatted sagittal CT images and the sagittal tomograms (TG) were compared for evaluating the accuracy of the condylar position measurements. Impressions of the joint space were obtained in order to estimate the actual dimensions. The CTs, TGs and impressions were measured with a profile projector. The errors, differences between the values from the impressions and the values from CTs and TGs, were calculated.
The reformatted sagittal CT images of 40TMJs in 20patients were also observed for clinical evaluation.
The results were as follows:
1) The reformatted CT images from the coronal scan projected at 90°, 80°or 70°to the F-H plane clearly depicted the condyle and fossa.
2) The mean measurement error on the CTs was 0.1mm and that on the TGs was 0.25mm.
3) The measurement error on the TG in one of 6 TMJs was especially great while the measurement errors on the TGs in the other 5 TMJs were of the same range of the CTs. Therefore, there ma a considerable number of errors in the measurement on the TGs in the case of particular morphological types of joints.
4) The reformatted sagittal CT images from the coronal scan of 28 TMJs were clearly depicted the condyle and fossa in the same manner as the dried skulls.
These results suggest that the sagittal CT reformatted from the coronal scan is useful for accurate measurement of the condylar position and clinical application on all types of TMJs.
