Light and electron microscopic study of autologous implants of dental roots in the subcutaneous tissue of rats.
Maxillary first molars of rats were extracted. The roots were separated and subsequently implanted in the dorsal subcutaneous tissue of the same animal. In Experiment 1, the roots were implanted immediately after removal; in Experiment 2, the roots were subjected to freeze-thawing (devitalized) before implantation. After 4, 8, and 15 weeks of implantation, the roots were removed and processed for light and transmission electron microscopy. Roots of Experiment 1 showed an amorphous clear material filling depressions on the irregular surface of the cementum. This material consisted predominantly of collagen fibrils. Cells adjacent to the amorphous clear material exhibited numerous cytoplasmic processes surrounded by collagen fibrils. Globular structures with an electron-opacity similar to that of neighbouring cementum were observed within the bundles of collagen fibrils. Multinucleated cells with features of osteo/odontoclasts were often closely apposed to deep depressions of the cementum. In Experiment 2, only large multinucleated giant cells appeared around the surfaces of the roots. It seems therefore that, in Experiment 1, precementum formation and osteo/odontoclast mediated destruction occurred. It is likely that these activities may have originated from periodontal ligament cells carried to the implantation site. This conclusion is supported by the observation that such activities were absent in Experiment 2. Devitalized roots were unable to form precementum and were surrounded by foreign body giant cells.
Cerri
P S
PS
Department of Morphology, Federal University of São Paulo, Brazil.
Freymüller
E
E
Katchburian
E
E
D000818:Animals; D003787:Dental Pulp Devitalization; D008437:Maxilla; D008854:Microscopy, Electron; D008963:Molar; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014092:Tooth Root / Q000637:transplantation* / Q000648:ultrastructure; D019553:Tooth, Nonvital / Q000473:pathology; D014182:Transplantation, Autologous; D016042:Transplantation, Heterotopic