Abstract
The purpose of this study is to evaluate the effects of oral microorganisms and the conditions of the roots upon the reattachment of the gingiva to the denuded surface of the root. Experiments were performed using germfree (GF) and conventional (CV) rats. A small elastic ring was applied around the cervix of the mandibular first molar of the rat. The ring produced continuous pressure against the periodontium to make a pocket. The evaluation of the condition of the teeth and the periodontium was made on 0, 2, 4, 7, 14, 28 and 56 days following the removal of the rings from the teeth.
The histopathological pattern of the periodontium, the level of the epithelial attachment and the height of the alveolar bone were the items observed.
The results were as follows:
1. Periodontal pockets were produced by the elastic ring, applied for 14 days, both in GF and in CV.
2. The periodontal pocket in CV, measured at the removal of the ring, was about 1.5 times the depth of the one in GF.
3. Histopathological changes observed near the pocket in GF were the decrease of epithelial thickness and the hyaline degeneration together with irregular arrangement of the transseptal fibers. The changes in CV were the ulceration or the proliferation of the epithelium lining the lateral wall and the diffuse infiltration of round cells from the base of the pocket to the margin and to the alveolar bone. Numerous, newly formed engouged capillaries, and partial disappearance of the collagen fibers were also seen.
4. The resorption of the alveolar bone observed at the removal of the ring existed both in GF and in CV. The extent of the resorption in CV was greater than the one in GF.
5. The level of the base of the epithelial attachment in GF moved coronally, following the removal of the ring. This indicated that the reattachment process was in progress. The reattachment was significantly observed at the medial side. In CV, the apical migration of the epithelial attachment together with the proliferation of the epithelium was observed. Little change was seen at the distal side in CV.
6. The height of the alveolar bone in GF was not changed following the removal of the elastic ring. The reduction in the height of the alveolar bone was observed at the medial side in CV following the removal of the ring. Significant changes were not found at the distal side.
7. The histological pattern of the reattachment in GF at the medial side differed from the one at the distal side. The absorption of the cementum was often encountered and the collagen fibers arranged parallel to the root at the medial side. The pattern of the reattachment observed at the distal side was characterized by the collagen arrangement which was vertical to the surface of the root.
8. It was suggested that the gingival reattachment to the denuded surface of the root was strongly affected by the microorganisms and their metabolic products..
