Cementum attachment protein (CAP) has been isolated from bovine and human cementum and purified, and many of its properties studied. CAP is chemotactic for a subpopulation of periodontal ligament cells which selectively adhere to CAP and differentiate into cells that produce calcified cementum-like nodules in culture. Cells that produce CAP are present in periodontal ligament cell cultures as well as in alveolar bone. Recent studies show that the immunosuppressive drug cyclosporin A (CsA) stimulates deposition of cementum on tooth root surfaces and by cells located some distance from the tooth roots. Using CAP and CsA and beagle dogs, we proposed to develop a model in which cementum is laid down on the surface of titanium dental implants allowing ligamentous attachment to bone to form. There is evidence that this is biologically possible (Buser et al., 1990) Hydroxyapatite-coated titanium dental implants will be machined to allow for spaces of 0.5 mm or 1.0 mm between the implant surface and the bony wall. These will be coated with CAP, CsA or CAP/CsA and implanted into the edentulous ridge in dogs and flaps sutured.. Implants not coated with CAP or CsA will serve as controls. Standardized radiographs of the implants will be made monthly. After 4 months the animals will be euthanized and block sections of the jaws containing the implants harvested and fixed. Sections will be made of the calcified implant-containing blocks for light microscopic evaluation. The presence or absence of cementum on the implant surface and an organized ligamentous attachment of the implant to bone will be assessed. Successful development of the model will permit detailed studies on regulation of cementum deposition and ligament formation by agents such as oncostatin M. In addition, the case types in which implants can be used would be greatly expanded, including their use in children and in bridges and other constructions involving both implants and natural teeth.
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