The difference of regenerating speed between the epithelium and the secondary cementum may determine the extent of the fibrous reattachment of the flaps to the exposed surface of the roots. If the speed of the epithelium is higher than that of secondary cementum, the area of the fibrous reattachment will be restricted within the narrow limits.
The aims of this study are to estimate the influence of the surgical trauma and of the remnant of periodontal pocket upon the regenerating speed of secondary cementum, and to examine the effect of the regenerating alveolar bone on the apposition of secondary cementum.
The experiments were carried out on 26 dogs with healthy periodontal conditions. Maxillary 3rd incisors, canines, 1st premolars, mandibular 3rd incisors and canimes were used. The alveolar bone, 4x4mm, was chiseled away from the buccal margin. A groove was prepared on the surface of the apical border of exposed root.
Experiment I: After the alveolar bone, 4x4mm, was removed from buccal margin, and the groove was prepared, the flap was repositioned and sutured. The animals were kept alive from 1 to 25 weeks.
Experiment II: The alveolar bone was removed and groove was prepared as the experiment I. Then a sheet of alminium foil was inserted between the exposed surface of the root and the repositioned flap. The foils were kept in the place from 1 to 42 weeks.
Experiment III: The same procedures were taken place as the experiment II. At the end of the inserting period of the foils, periodontal flap operations were performed and the animal were kept alive for the additional 13 or 15 weeks.
The animals were sacrificed after the experimental periods ranging from 1 to 42 weeks, and the histopathological examination of the roots and the periodontia were performed.
The growth of the granulation tissue between the alminium foil and the surface of the root was observed. The periodontal pockets were not significant in all of the animals. The insertion of the alminium foil inhibited the regeneration of the alveolar bone. The differences of the regeneration of secondary cementum among the 3 groupes were not found. The maxillary 3rd incisors tended to receive more apposition of secondary cementum than the mandibular canines and premolars. The width of the alveolar bone removed, was related to the speed of the regeneration of the bone. No significant relationship was found between the regeneration of the alveolar bone and that of secondary cementum.
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