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For understanding of anatomy, physiology, and diseases of human TMJ, it is required to evaluate quantitatively the movement of the disc and condyle head of mandible. The histologic section of cadaver TMJ were examined, and the magnification of the MR image and its details of anatomy were evaluated. And then a quantitative analytic method, by comparing the Sectograph and the MR image of vital human. TMJ, was proposed. For this study, 15 subjects(male, 24~35years) were selected from a prosthodontic examination randomly, and each subject’s five interocclusal rubber registration records were made on the ICP, and 5, 10, 15, and 20mm jaw opening positions. All subjects were radiographed with a Denar Quint Sectograph Image System (Denar Corp. USA),and imaged with a MRP-20EX MR Image System(0.2T, Permanent Mgnet Type, Hitachi Medical Corp, Japan) using an 100mm diameter bilateral type surface coil. These images were traced on the acetate tracing paper, and analyzed. @ES In this study, the findings led to the following conclusions. @EN 1. In comparison of the histologic section of autopsy specimen weth the MR image at the same section, the size (dimension) of MR image was 70% of the real one. It was possible to recognize the shape of articulr disc, anterior and posterior attachments, and adjacent soft tissues, because of the excellent reproducibility of anatomical structure. 2. When we compared the amount of joint space on MR image with that of joint space on sectograph, the amount of joint space on sectograph was significantly greater than that of joint space on MR image, except at the top of condylar head. 3. The position of minimum joint space on sectograph at intercuspal position didn’t coincide with the middle position of articular disc on MR image, and was approximately in the anterior third of posterior band of articular disc. 4. The amount of condylar movement on MR image at opening movement was greater than that of articular disc movement. From intercuspal position to 5mm jaw-opening movement, the condylar movement showed hinge one, and over the range 5mm jaw-opening, it suggested hinge & translatory one. 5. In terms of area variation of articular disc measured on MR image in sagittal plane, the area of posterior band increased with increasing the amount of jaw opening, but the area of anterior band decreased conversely.
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