乳歯窩洞形成後の歯髄組織の変化に関する神経組織学的研究
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概要
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Cavity preparation was performed on deciduous teeth characterized by physiologic root resorption, and general changes in the pulp and the state of nerve fibers in the pulp were investigated. The results were as follows : 1. Thirty minutes after the cavity preparation, no changes were observed in the predentin and odontoblastic layer at the cavity floor and at the regions of the cavity walls. In the cell-free and the cell-rich layer adjacent to the odontoblastic cells and in the dental pulp, no reactive inflammatory state was observed. As for distribution of the nerve fibers, no changes were observed. 2. After 24 hours, appearance of rods was significant in the dentin and predentin at the cavity floor and the regions of the cavity walls and no nerve fibers were observed in these areas. Because of the reactive inflammatory state, atrophy and disappearance of the odontoblastic cells directly under were extensive, the junction between the cell-free and cell-rich layers become indistinct, and inflammation extended as far as the central region of the dental pulp. Although most of the nerve fibers in these areas disappeared, some degenerative nerve fibers showing laceration or granular destruction were still observed. In the healthy odontoblastic cells and cell-rich layer slightly under the regions of the cavity walls, small nerve bundles, small nerve fibers, and single nerve fibers were still observed. 3. On about third day, appearance of rods decreased in number as compared with that after 24 hours and was rarely observed on 7th day. Reactive inflammatory state still continued but showed a tendency to disappear. On 3rd and 7th days, appearance of regenerated nerve fibers from the healthy pulp tissue under the regions corresponding to the cavity walls was observed significantly. 4. On 14th day, formation of the stroma of predentin was in progress at the cavity floor and the regions corresponding to the cavity walls, and inclusion of cells in it was observed in places. Ovoid cells, polymorphous cells, and taller cells were observed adjacent to the stroma. Relatively larger cells were beginning to be disposed and differentiated into odontoblastic cells presenting the morphology resembling odontoblastic cell. In the nerve fibers distributed nearby, medium nerve bundles, small nerve bundles, and single nerve fibers were noticeable and they ran relatively monotonously. 5. After 35th days, formation of secondary dentin was observed directly under the cavity floor and the number and running of dentinal tubules were distinct and regular in the transitional region from primary dentin but dentinal tubules were still indistinct in the central region of the secondary dentin. Odontoblastic cells directry under the secondary dentin were arranged regularly for the most part. The cell-free and cell-rich layers were indistinct and a few inflammatory cells were observed in the dental pulp. Relatively abundant nerve fibers were beginning to be observed in the dental pulp directly under the secondary dentin, and congregation of some nerve fibers was noticeable. They were beginning to present compactness through complexity and anastomosis. 6. On 95th day, the secondary dentin formed was thicker than that on 35th day, and the dentin presented the dentinal tubular structure quite similar to that of the primary dentin. The predentin and odontoblastic layer were about normal. The cell-free layer and cell-rich layer were clearly demarcated. At this time, the distribution of nerve fibers was abundant, several nerve fibers congregated in bundles, and minute nerve fibers branching out from them began to appear. They were more compact and formed plexuses as compared with those on 35th day and were beginning to form Raschkow's plexus. Although very few in number, inflammatory cells were observed in the dental pulp.
- 九州歯科学会の論文
- 1984-02-25