歯根未完成歯の根尖閉鎖に関する実験的研究
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概要
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Immature permanent teeth, numbering 72 in 34 young mongrel dogs, were given root canal filling with Calvital, a calcium hydroxide, after pulp extirpation. Radiological and histopathological investigations were then made of apexification and the healing process. The results were as follows : 1. In radiological investigations, the apex showed continuity of radiopacity on the 35th day after treatment and much denser radiopacity after the 62nd day in the control groups. In the experimental groups, appearances of radiopacity were observed from the 62nd day and these were recognized more clearly on the 180th day. 2. In histopathological findings between the 1st and the 3rd day after treatment, Hertwig's epithelial sheaths and the external layer of the periodontal membrane were necrotic. Calcific clods appeared in the necrotic layers and in the adjacent healthy tissue and showed a positive von Kossa reaction. 3. Between the 7th and the 14th day, part of the necrotic layers dissolved and was resorpted and giant cells appeared. The calcific clods gradually decreased in number and in size. 4. On the 21st day, apical closure by cellular cementum, though irregular because of many and thick accessary roots, was observed in the control groups. In the experimental groups, many giant cells appeared around the necrotic tissue, but the periodontal membrane showed a trend toward recovery. Many young fibers and capillary vessels were observed. 5. On the 35th day, the calcific clods seen to the 21st day disappeared. In the external layer of the periodontal membrane under the residual medication, thick bundles of collagen fibers were seen running vertically toward the root canal. This finding was recognized as the commencement of calcification. Arrangement of the periodontal membrane was irregular in comparison with that in the control groups. 6. On the 62nd day, apexification by cementum-like tissue began and nearly complete apexification was observed in part. Around the hard tissue formed, cementoblast-like cells were seen and collagen fibers penetrating from the periodontal membrane were observed between these cells. 7. On the 180th day, the cementum-like tissues formed became thicker and accessary-root-like tissues were observed in these tissues. However, no complete apexification was observed. 8. No dentin formation was observed in any of the experimental groups, nor was growth of root observed. 9. Hertwig's epithelial sheath became necrotic on the 3rd day and disappeared thereafter. Its relation with apexification and growth of root was not recognized.
- 九州歯科学会の論文
- 1980-11-25