実験的咬合異常がラット下顎頭に及ぼす影響に関する病理組織学的及び走査電子顕微鏡的研究

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There are various studies in which malocclusion was experimentally induced and its influence on the temporomandibular joint was histopathologically examined. The mandibular condyle, especially the cartilaginous layer undergoes main changes, which are greatly varied and on which there has been no uniform view yet. Therefore, in order to make a more minute examination of the influence of malocclusion on the temporomandibular joint, malocclusion was experimentally induced in rats by upper, right and left, total molar extraction (A group, forty animals) and by periodic grinding of upper, right and left incisors plus the foregoing total extraction (B group, forty animals), and histopathological and scanning electron microscopic examinations were made of the changes in the mandibular condyle. The results were as follows : 1. Both experimental A and B groups showed the same weight gain tendency as control group. 2. Specific changes were observed early at the embryonic zone ranging from the central to internal area in experimental A group. a. Light microscopic observations revealed that from the first post-operative week, cells in the area adjacent to the articular zone presented roundness. These cells covered the entire embryonic zone at the sixth week, and thereafter the cellular arrangement became irregular with an increase in cartilage matrix. b. SEM observations revealed that from the first post-operative week, cells near the articular zone presented many processes, which continued to grow up remarkably up to the second week, and the cells presented roundness morphologically. Thereafter these processes decreased and from the ninth week the collagenous fibrils of the matrix traveled irregularly in part. 3. Greater specific changes were observed early at the embryonic zone of the internal area in experimental B group than in experimental A group. a. Light microscopic observations revealed that the cartilage matrix increased by the week, and that cellular morphology presented roundness and cellular arrangement became irregular to the most remarkable extent at the fourth week. Thereafter cellular arrangement became a little regular, but cellular morphology presented more roundness and was no longer distinguishable from the transitional zone. b. SEM observations revealed that changes of the collagenous fibrils of the matrix began as their disturbed traveling, leading to their small fasciculation to the most remarkable extent at the fourth week. Thereafter their traveling became regular and showed a tendency toward compactification. 4. The cartilaginous layer of the mandibular condyle was already thin, especially at the hypertrophic zone, at the third post-operative day in both experimental A and B groups. However, by the third week the layer became hypertrophic inversely, and from the fourth week it was re-thinned. 5. In neither A nor B group any great change was observed at the external area of the mandibular condyle. 6. Bone resorption of the lateral pterygoid attached bone margin of the mandibular internal neck stopped almost completely at the ninth week in control group, while in experimental groups there still remained bone resorption picture even then. 7. Ossification of the mandibular condyle proceeded in the order of control group, experimental A group, and experimental B group. The above results suggested that difference in malocclusion was correlated with the extent of abnormality of the temporomandibular joint.
九州歯科学会の論文
1985-02-25

実験的咬合異常がラット下顎頭に及ぼす影響に関する病理組織学的及び走査電子顕微鏡的研究

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