切削荷重が歯髄へ及ぼす影響
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概要
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In order to investigate the effect of the difference in magnitude of cutting load, one of the cutting conditions, on the dental pulp immediately after cutting in cavity preparation by high-speed cutting on vital tooth, a cutting device capable of exerting a given cutting load was designed. With the use of this device, 80g or 120g cutting load was applied on the six lower anterior teeth of dogs in performing cutting preparation, and light and electron microscopic observations were made. The results were as follows : 1. Scanning electron microscopic observation of the three dimensional structure of dentinal fibers of non-cut dogs' teeth with application of cryofracture and the HCl-collagen digestive method showed that most of the dentinal fibers, as in the human teeth, ran in the three dimensional curve from the odontoblasts arranged in a line and reached the enamel-dentin junction. 2. Light microscopic observation of cavity preparated teeth of dogs showed irregular arrangements, reticular atrophy, and appearance of aspirated bodies in the odontoblasts under the cavity in both 80g and 120g cutting load cases. At the same time, no significant changes were observed in the proper dental pulp under the odontoblasts. 3. Aspirated bodies appeared in 52% of cavity preparations with 80g cutting load and in 60% of 120g load. 4. The fact that the aspirated bodies which had appeared immediately after cavity preparation showed Feulgen positive nuclear reaction suggested that each was the nucleus of the odontoblast. 5. Transmission electron microscopic observation showed morphological changes in odontoblasts in both 80g and 120g preparation cases. Namely, atrophy, pyknosis, and aspiration of some or most the nuclei of odontoblasts which penetrate into the dentinal tubules were observed. However, alterations of the odontoblasts in 120g preparation were more conspicuous than those of 80g preparation. Almost all of the aspirated bodies observed in 120g preparation were located deeply in the dentinal tubules and their nuclei occasionally showed dissolutive appearance. 6. It was suggested that one of the pathogenesis for the appearance of aspirated bodies might result from dragging-in of the dentinal fibers by air-turbine revolution. 7. It was observed in this study that the less cutting load made the impairment to the odontoblast slighter. The necessity of less cutting load in clinical work was confirmed again.
- 九州歯科学会の論文
- 1984-02-25