PubMed · 2382088
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J M Sautier. 1990. [Root growth].. https://pubmed.ncbi.nlm.nih.gov/2382088/
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OBJECTIVE: Enamel matrix-derived proteins (EMD) are thought to trigger the formation of acellular extrinsic fibre cementum (AEFC), while other reports indicate that EMD may have osteogenic potential. The aim of the present study was to characterize the tissues developing on the root surface following application of EMD. METHODS: Twelve human periodontitis-affected teeth, scheduled for extraction, were treated with EMD. Two to 6 weeks later, the teeth were extracted, demineralized and processed for embedding in acrylic and epoxy resins. New tissue formation was analysed by light and transmission electron microscopy. RESULTS: New tissue formation on the root was observed in the notch and on both scaled and unscaled root surfaces distant of the notch area in six defects. The newly formed tissues on the root were thick, collagenous, devoid of extrinsic fibres, and had an irregular surface contour. The presence of electron-dense, organic material in the collagenous matrix indicated at least partial mineralization. Embedded cells were numerous and the cells on the matrix surface were very large in size. Abundant rough endoplasmic reticulum and a prominent Golgi complex were evident. The presence of a split between the treated root surfaces and the newly formed tissue was a common observation, as was the presence of bacteria and host cells in the interfacial gap. CONCLUSION: Following treatment with EMD, a bone-like tissue resembling cellular intrinsic fibre cementum may develop on the root surfaces, instead of AEFC. Furthermore, EMD may both induce de novo formation of a mineralized connective tissue on scaled root surfaces and stimulate matrix deposition on old native cementum. Interfacial bonding appeared to be weak after 6 weeks of healing.
The structure of reparative tertiary dentin in human deciduous teeth has been studied. Reparative dentin is secreted by a new generation of odontoblast-like cells which have been subject to strong stimuli, e.g., trauma or deep active caries lesions with associated pulp inflammation. Ground sections of 25 teeth were prepared, and contact microradiographs were produced. Another 30 teeth were demineralized, embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Some demineralized sections from each tooth were also studied in the scanning electron microscope. Most of the teeth showed some type of tertiary dentin formation. Mineralized tissue with a varied morphology was observed. In teeth which had been subject to trauma, the entire pulp chamber was sometimes obliterated. Mineralization seemed to start in the incisal region, and the central part of the pulp was the last part to be obliterated. Radiolucent voids and canals were seen. The organic matrix was dense and fibrous. In the pulp chamber and especially in the root canals, resorption had often occurred, indicating that signals giving rise to odontoclasts were also present. Resorption was often followed by deposition of various amounts of cementum-like repair tissue. The cells responsible for the formation of reparative dentin are believed to be subodontoblasts or undifferentiated ectomesenchymal cells. The varied morphology of the reparative dentin, observed in the pulp of the teeth examined, indicates that different stimuli lead to induction of hard-tissue-forming cells which produce different types of hard tissue.
It was recently shown that application of enamel matrix derivatives (EMDs) on denuded root dentin promotes periodontal regeneration. EMD is shown to adhere to the etched dentin, but its adherence to root-end filling materials is not known. The purpose of this study was to evaluate the adherence of a commercially available EMD product to root-end filling materials. Dentin sections were embedded in blocks made of acrylic resin. Cavities were prepared in similar acrylic resin blocks and were filled with amalgam, IRM, or composite resin. EMD was labeled with radioactive iodine and applied to the surfaces of the dentin sections, freshly made fillings, or acrylic resin controls. The specimens were rinsed, and the amount of radioactive iodine was determined in a gamma counter. Substantial amounts of EMD adhered to dentin sections. EMD adherence to amalgam and IRM was significantly less than to dentin or composite resin.