Abstract
The purpose of the present study was to clarify the mechanism of the fibrous attachment accompanied with the new cementum formation following flap surgery at the fine level. Three adult monkeys were used in a standardized flap operation; Mucoperiosteal flaps were made on the buccal aspect of 5 4/6 5|4 5/5 6 and elimination of alveolar bone approximately 2mm to the apical direction was performed. In order to expose the dentin surface, the root cementum was curetted. The surgical procedure and sacrifice of animals were scheduled to allow for observation periods of 2, 3, 4, 5, 6 and 8 weeks. The biopsies including the tooth, gingiva and bone were comparatively examined in light and electron microscopes.
The results obtained were as follows:
Light microscopical: Connective tissue reattachment to the dentin surface was observed two weeks postoperatively, subsequently the new cementum was deposited in the notch and the cementoid was also deposited on the dentin surface at three weeks. In the specimens obtained at longer intervals the new cementum formation took place coronally. Especially in the specimen obtained at six weeks, a considerable regeneration of the alveolar bone took place and the new cementum was also deposited from the notch to the termination of the junctional epithelium.
The resorption lacunae on the dentin surface were observed two weeks postoperatively as well as longer periods.
Electon microscopical: In early stage of healing, elongated fibroblasts were aligned parallel to and in close proximity to the dentin surface. Subsequently, the initial cementum, which were deposited over the dentin surface, consisted of individual collagen fibrils frequently running parallel or in a haphazard manner. As the new cementum increased in thickness, the superficial cementum was visible in well-defined fiber bundles. Cementoblasts were observed synthesizing collagen fibrils adjacent to the new cementum. A dense granular layer was present between the dentin surface and the regenerated connective tissue, or between the former and the new cementum.
In the resorption areas which arose on the dentin surface the dense granular layer was not visible when odontoclasts were actively involved in the dentin resorption. In accordance with reduction of the odontoclastic activity, collagen fibrils were quickly formed adjacent to the resorbed dentin surface and the dense granular layer was visible again. In these areas interdigitation of newly formed collagen fibrils with denuded ones on the resorbed dentin surface was observed, resulting in a more intimate union of the tissues.
