Repair in Different Zones of the Periodontium After Tooth Reimplantation

This study was undertaken to clarify the dynamics of tissue repair in the transseptal region and periodontal ligament after tooth reimplantation. Twelve teeth, distributed in four squirrel monkeys, were extracted and reimplanted within 3 minutes. The reimplantation schedule provided three teeth at 1, 3, 7 and 21 days after reimplantation. Tritiated proline was injected 8 hours before animal sacrifice. Histologic characteristics and autoradiographic grain densities were compared in the transseptal and periodontal ligament areas. One day after reimplantation there was a distinct break in the continuity of transseptal and periodontal ligament fibers. Regions bordering the tear, and the entire ligament, were virtually acellular. Cell repopulation was occurring in the transseptal region at 3 days, in contrast to the ligament which was still acellular. At 7 days, cell repopulation appeared complete in the transseptal area, and new fibers were evident bridging the tear. The periodontal ligaments still had acellular areas, lacked fiber continuity, and were repopulating primarily from the adjacent alveolar bone which had enlarged marrow spaces and active osteoclastic resorption. Proline grain density was significantly greater in the transseptal area compared with the periodontal ligament. In 21 day specimens, the transseptal region appeared normal. Although cell repopulation and restoration of fiber continuity had occurred in the periodontal ligament, normal orientation was absent. Grain density in the periodontal ligament was significantly greater than in the transseptal region. The results indicated that healing after tooth reimplantation occurred more rapidly in the transseptal region than within the periodontal ligament. The transseptal healing resembled that reported following incisional wounds, whereas healing in the periodontal ligament was dependent primarily upon repopulation from the adjacent alveolar bone.