残根の生物学的研究

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A biological study was undertaken on the correlationship possibly existing between the tooth stump remaining in the mandible and its neighboring tissues. Tooth stumps were prepared in dogs as experimental animal from both vital teeth and non-vital filled teeth, and longitudinal observations ware made patho-histologically for possible changes occurring in the tooth stump and its periphery. Results were summarized as follows. 1) After preparation of the tooth stumps, some remained in the original site, while others moved toward the oral direction and some of these came to show the amputated end in the mouth. This movement of the stumps largely depends on the extent of injuries to which the neighboring tissues suffered and other various factors. 2) In early stages of post operation, there was always inflammatory symptom seen in the periphery of stumps. The intensity of the inflammation also depends greatly on the severity of surgical attack given to any tooth. The inflammation disappeared sooner when it dealt with the stump containing the vital pulp and when the surgical attack for preparing the stump was mild. In the cases where the stump contained necrotic pulp or was treated with root filling material, these continued to irritate the tissues and prolong the inflammation considerably. 3) Regeneration of bone tissues at the site where the tooth was separated from its root began earlier or later depending on the severity of surgical attack given. Regeneration of bone was also affected by the kind of root filling materials used in the experiment and further by such factor as death or life of the tooth pulp involved. When regeneration of bone was retarded traveling of the stump became greater. 4) There were often observed resorption occurring in the periphery of stump. The resorption may have been caused as results of pathologic change of the root stump into foreign body or as consequence of inflammation which occurred in the stump's peripheral tissues. This phenomenon was seen more frequently in root-filled teeth. 5) Apposition of cementum substance on the stump surface was frequently observed. This may be related to increased proliferative drive in the tissues near the focus of inflammation on one hand, but there may also be operating an effect of uncontroled activity on the side of cementoblast cells as resulted from abolition of occluding function. 6) The apposition of cementum on the surface of cut end of stump may be seen in those cases where dense connective tissues resembling those of periodontal membrane have covered the part adjoining stump's cut end. 7) Among the experimental tooth stumps containing vital pulps, some lost their pulps in necrosis and others kept them intact. The necrosis occurred most frequently in those cases where the surgical attack was severe, accompanying severe inflammation. In cases of stump where the pulp was kept in vital state and where no sign of movement was noticed with the stump itself, the pulp was considered to be keeping a vital communication with the periodontal membrane through the apical foramen, and the periodontal membrane was considered to be playing its biological role in detaining the stump on the spot. 8) The periodontal membrane remaining around the tooth stump was shown to have suffered certain destructive changes due to inflammation, and there occurred even some degenerative symptoms such as hyaline degeneration. It may be generally stated that severer the pathologic change of periodontal membrane, greater the movement of the tooth stump, suggesting that there existed a distinct correlationship between the appearance of periodontal membrane and the tooth stump as buried in the mandible. 9) On the other hand, however, there were frequent instances of stumps which were intimately connected with periodontal membrance in spite of the fact that they were moved in considerable distances. Around the surface of these stumps, there did not exist any fraction of alveolar bone, and, instead, the surface of these stumps was connected with both granular tissues and bone marrows by dint of the periodontal membrane. These findings suggested the presence of an organic association between the periodontal membrane and the cementum which was not readily destructible.
九州歯科学会の論文
1978-03-31

残根の生物学的研究

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