ラット臼歯歯根膜における神経線維分布の加齢的変化に関する研究

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Studies were carried out on the age changes of the nerve fibers, innervation to the periodontium of the rat molars from the stage of the root formation, one month after birth, to the aged stage, two and a half years after birth, through the stage of the completed root formation. The following results were obtained. 1. At the stage of root formation, the periodontal space was vast and the periodontal membrane was cellular with enormous collagen fibers, but undeveloped periodontal fiber bundles. The nerve fibers supplying the periodontal membrane penetrated through the vasoneural channel straight underneath the root apex and the interdental channel opening on the alveolar wall. At this stage the innervation was totally scanty, and the scantiness rates were in the order as follows : at the middle portion of the root and bifurcation, at the alveolar crest, and the root apex. The nerve fiber bundles mainly passed along the vessels near the alveolar wall. 2. As the root apex formation progressed, the periodontal fiber bundles were developed and showed the functional arrangement. The nerve fibers showed a gradual distribution in the periodontal membrane at the middle lateral portion of the root and the side of the cementum. When the root apex was completed in five months after birth, the nerve fibers were the most abundant. 3. The proliferation of the secondary cementum at the root apex was marked, and the periodontal spaces were strangulated, and the periodontal fibers showed the irregular functional arrangement with aging from six months to one year after birth. The degenerative findings such as the separation between the fibers of nerve fiber bundles, the partial swelling of the nerve fibers and the lowering of staining, were observed. 4. After the first postnatal year, the degeneration of the nerve fibers increased with aging and the degeneration with the form like a string of beads was abundantly seen. The intact nerve fibers were frequently observed in the portion where the remarkable strangulated periodontal membrane and no functional arrangement of the periodontal fiber bundles were seen ; on the contrary no degenerative change was seen in the portion where the intense degeneration of the nerve fibers was observed in the periodontal membrane. Therefore no correlation between the changes of periodontal membrane and the degeneration of the nerve fibers was noted. 5. After the second postnatal year, the advanced marginal periodontitis and dental caries abundantly appeared, and the functional arrangement of the periodntal membrane almost disappeared. The degenerated nerve fibers were numerously noted. It was suggested that the effect of periodontal disease as well as the aging changes exerted a synergistic action on the remarkable appearance of the degenerated nerve fibers.
九州歯科学会の論文
1985-02-25

ラット臼歯歯根膜における神経線維分布の加齢的変化に関する研究

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