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Dental Tribune Middle East & Africa Edition

38 Dental Tribune Middle East & Africa Edition | May - June 2014implant tribune > Page 39 < Page 37 are not considered as versatile as embryo stem cells because they are widely regarded as multipotent, that is, capable of giving rise to certain types of specific cells/tissues only, whereas the embryo stem cells can differentiate into any types of cells/tissues. Advances in scientific research have deter- mined that some tissues have greater difficulty regenerat- ing, such as the nervous tissue, whereas bone and blood, for instance, are considered more suitable for stem cell therapy. In dentistry, pulp from primary teeth has been thoroughly in- vestigated as a potential source of stem cells with promising results. However, the regener- ation of an entire tooth, known as third dentition, is a highly complex process, which de- spite some promising results with animals remains very far from clinical applicability. The opposite has been observed in the area of jawbone regenera- tion, where there is a higher level of scientific evidence for its clinical applications. Cur- rently, adult stem cells have been harvested from bone marrow and fat, among other tissues. Bone marrow is haematopoi- etic, that is, capable of produc- ing all the blood cells. Since the 1950s, when Nobel Prize winner Dr E. Donnall Thomas demonstrated the viability of bone marrow transplants in patients with leukaemia, many lives have been saved using this approach for a variety of immunological and haema- topoietic illnesses. However, the bone marrow contains more than just haematopoietic stem cells (which give rise to red and white blood cells, as well as platelets, for example); it is also home to mesenchymal stem cells (which will become bone, muscle and fat tissues, for instance; Fig. 3). Bone marrow harvesting is carried out under local anaes- thesia using an aspiration nee- dle through the iliac (pelvic) bone. Other than requiring a competent doctor to perform such a task, it is not regarded as an excessively invasive or complex procedure. It is also not associated with high levels Fig. 5a: A bone graft being har- vested from the chin (mentum). Fig. 5b: A bone graft being harvest- ed from the angle of the mandible (ramus). Fig. 5c: A bone graft being har- vested from the angle of the skull (calvaria). Fig. 5d: A bone graft being harvest- ed from the angle of the leg (tibia or fibula). Fig. 5e: A bone graft from the pelvic bone (iliac). Fig. 6: A critical bony defect created in the skull (calvaria) of a rabbit. Fig. 7: A primary culture of adult mesenchymal stem cells from the bone marrow after 21 days of culture. Fig. 8a: A CT image of a rabbit?s skull after bone-sparing grafting without stem cells (blue arrow). Note that the bony defect remains. Fig. 8b: A CT image of a rabbit?s skull after bone-sparing grafting with stem cells. Note that the bony defect has almost been resolved. Fig. 9: A bone block from a mus- culoskeletal tissue bank combined with a bone marrow concentrate. Fig. 10a: A histological image of the site grafted with bank bone com- bined with bone marrow. Note the presence of considerable amounts of mineralised tissue. Fig. 10b: A histological image of the site grafted with bank bone not combined with bone marrow. Note the presence of low amounts of min- eralised tissue.

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