[An experimental study on healing process of replanted mature permanent teeth. Changes of periodontal vascular network].

This study was conducted to clarify both changes of periodontal vascular architecture and concomitant remodelling phenomena associated with hard tissues in the healing process of replanted teeth of first premolar. Utilizing both vascular corrosive resin casts method, scanning electron microscopy, and histological examinations, 45 matured mongrel dogs were used for this study. The results were as follows: 1. 4 days after operation: Newly formed vascular networks with a exceedingly irregular course were observed on lower two thirds of the alveolar wall. They derived from comparatively less damaged periodontal vascular components. No vascular networks were observed surrounding in the crevicular area of the replanted tooth where the periodontal membrane tissue was thoroughly damaged when tooth was extracted. 2. 1 week after operation: Newly formed periodontal vascular networks with a slightly irregular course were observed over the entire alveolar bone surface. 3. 2 weeks after operation: Formation of Sharpey's fibers occurred. The surrounding alveolar bone was remodelled and rearrangement of periodontal vascular architecture was observed. Also, several Howship's lacunae were observed on the root surface where characteristic capillary loops with glomerular-like appearance penetrated into these lacunae. 4. 3 weeks after operation: Root resorption was advanced and capillary loops with glomerular-like appearance were extensively distributed in association with each lacunae. On the other hand, the less space where periodontal membrane vasculature occupied, the more space was occupied by osteoid tissue. 5. 4 weeks after operation: Blood vessels within the periodontal space were reduced in number and the osteoid tissue showed bony fusion adjacent to the extensively resorbing surface of dentin. 6. 12 weeks after operation: Functional arrangement of Sharpey's fibers was completed. Restoration of Howship's lacunae on the root surface and two layered arrangements of vascular network within the periodontal space were observed. Newly formed periodontal vascular architecture showed a fine meshwork pattern, which was somewhat different from that of the control (noreplantation) group. 7. 20 weeks after operation: Increased number of capillary loops was observed with leakage of methacrylate resin through the weakened endothelial linings of capillaries in one case. It is supposed that this leakage through capillaries is correlated with the inflammatory root resorption that occurs clinically in marginal periodontitis. Also in some cases, periodontal capillary network showed secondary occlusal traumatic changes. Above results indicated that periodontal vascular architecture varied depending upon the reactions of periodontium following tooth replantation and the prognosis of replanted tooth was deeply associated with repair of periodontal vascular network.