FC 断髄における歯髄内神経線維の消長について

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The aim of this paper is to determine whether or not formocresol technic fulfills its purpose as vital pulpotomy. A histopathological investigation therefore was made of the behavior of nerve fibers in the residual pulp tissue after pulpotomy, which contributes to the clinical diagnosis of vitality of pulp tissue. Of the rats in which vital pulpotomy was performed by formocresol technic, 111 out of 120 cases retained vital pulps up to three months after operation, and these 111 cases were examined chronologically. The results were as follows : Pulp tissue findings 1. No uniform changes were observed in tissue fixation effect of formocresol. Some showed fixation as far as the middle or the apical third of the pulp on the first day after operation. Initially, a necrobiotic layer, in which the cell number was greatly reduced with hypochromatosis, was observed in the border between the fixed layer and vital residual tissue. 2. On the third day after operation, proliferation of fibroblast-like cells was observed in the vital residual tissue. From the seventh day after operation, the necrobiotic layer and fixed layer were replaced by granulation tissue. Thereafter, apposition of osteodentin was observed in the root canal walls. 3. In the cases in which apposition of osteodentin was significant in the middle third of the pulp, the residual pulp tissue was normal. However, in the cases in which the apposition of osteodentin was limited, the reparative term for the residual pulp tissue was long and granulation tissue took a turn for fibrosis. Neuro-histological findings 1. The nerve fibers below the pulpotomy site were fixed by formocresol as far as the middle third of the pulp on the first day after operation, and degenerative findings of the nerve fibers were observed in the portion further below. Degeneration extended to the apical third of the pulp in some cases. 2. On the third day after operation, proliferation of fibroblast-like cells was observed in the residual pulp tissue, and the nerve fibers were in a stage where findings of the beginning of regeneration and findings of degeneration were concurrent. 3. Between the seventh and fourteenth days after operation, the regenerated nerves were extending toward the region below the pulpotomy site, along with the replacement of the necrotic region (fixed layer and necrobiotic layer) by granulation tissue. 4. After 14th day after operation, degeneration recurred from the periphery of the regenerated nerve and macrophage was observed in the adjacent area. 5. From 30th to 92nd days chronologically, chronic inflammation, fibrosis, and apposition of osteodentin were in progress, and the nerve fibers were degenerating and disappearing again from the superficial layer to the apex and were reduced in distribution. On the basis of the foregoing histological findings on pulp tissue and nerve fibers, formocresol technic may be evaluated as acceptable as vital pulpotomy. However, the cases in which apposition of osteodentin was insufficient showed a tendency toward a reduction in the residual pulp tissue quantitatively and toward fibrosis qualitatively. Also, the cases of total necrosis of the pulp were inclined to increase in number chronologically. For these reasons, a further long-time observation, including nerve fibers, is necessary in the future.
九州歯科学会の論文
1983-02-25

FC 断髄における歯髄内神経線維の消長について

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