| Co-Investigator(Kenkyū-buntansha) |
BABA Otto Tokyo Medical and Dental University, Bioatructural Science, Research Associate, 大学院・医歯学総合研究科, 助手 (90251545)
SAKAMOTO Yujiro Tokyo Medical and Dental University, Biostructural Science, Research Associate, 大学院・医歯学総合研究科, 助手 (90242205)
TERASHIMA Tatuo Tokyo Medical and Dental University, Biostructural Science, Associate Professor, 大学院・医歯学総合研究科, 助教授 (20114770)
TAKAHASHI Nobuyuki Seikagaku-Kogyo Co. Ltd. Tokyo Research Center, Investigator, 東京研究所, 研究員
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| Research Abstract |
In order to elucidate the role of enamel matrix proteins in the regeneration of periodontal tissues such as cementum, alveolar bone, and periodontal ligament, and also to reveal the mechanisms whereby the spatial arrangement of these tissues is determined, the following in vivo experiments were attempted.
(1) Induction of hard tissue formation by the enamel matrix proteins in the periodontal ligament of the HEBP-affected guinea pig tooth ; A long term administration of HEBP, a type of bisphosphonates, to the guinea pig caused a leakage of newly formed enamel matrix proteins into the periodontal ligament, and formed the "enamel matrix pools". Bone or cartilage-like tissue was formed around the enamel matrix pools as well as on the enamel surface being exposed by disruption of the enamel organ at the secretory or early stage of maturation. These data implicated a potential of enamel matrix proteins to induce differentiation of dental follicle-derived PDL cells into hard tissue forming cel
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(2) Tissue reactions on the exposed enamel surface in the ectopic transplantation model of rat incisors :The incisors extracted from young rats were immediately freed of the enamel organ and transplanted subcutaneously in the dorsal region of the littermate animals. First, cells attached to the immature enamel surface displayed rich cytoplasm, and extended numerous cytoplasmic processes deep into the enamel, preferentially through the interprismatic regions. These cells deposited mineralized matix and by 4 weeks, thick layers of bone or cementum-like tissue was formed on the enamel. Deposition occurred only on the immature enamel surface, and also only in a small percentage of the transplanted incisors.
(3) Effect of enamel matrix proteins on the peripheral connective tissue : Administration of EMDOGAIN (a crude extract of immature porcine enamel) in subcutaneous or intramuscular regions did not induce osteogenic or cementogenic cells nor the deposition of mineralized tissues. Same result was gained when pieces of immature enamel isolated from rat incisors were embedded in the subcutaneous regions.
These data suggested that enamel matrix proteins have no substantial effects on the peripheral connective tissue but have a potential to induce dental follicle-derived undifferentiated cells to become hard tissue forming cells, and to facilitate regeneration of periodontal tissues. Less
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