A Study on Movenent of TMJ Condyle and Disk with Magnetic Resonance Imaging

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The purpose of this study is to investigate movement of TMJ condyle and disk. MRI instruments were used to observe movement of TMJ disk which is really soft tissue and TMJ condyle. Taking condyle and disk by MRI has started recently, and its technical conditions have not been established yet. Therefore, this study was firstly set out to establish them.Two MRI instruments, 1.5 and 0.2 tesra, were used in this study. Comparing from one another, it was found that MRI of 1.5 tesra was superior to that of 0.2 tesra as regard to the S/N ratio and clearness of pictures, but that the later one was enough to be clinically used.As for the coil, an improved surface coil was used. The characteristics of this coil are those ; It makes the imagine time shorter and patients feel less suffering since it can take both sides of TMJ at the same time. However, the coil should be improved still more, because it is not useful enough to judge accurate position and movement of the disk.At the present time, no other means are left except dividing mandibular movement into several fixed points where the distance is 0, 2, 4, ・・・Millimeters away from maximum opening point and taking MRI at each point for analysing the movement of TMJ with MRI. Therefore, Their Mandibular Movement on cine film were not so smoothed and could be very different from their real one.In this study, the right disk of the patient was judged to be situated anteriorly from the condyle at the maximum opening point, and the right condyle resorbed more than the left. Judging from these, the patient might have a problem with right TMJ. This results coincided with his clinical complaints, and the MRI instrument is probably useful to diagnose TMJ dysfunction.