CAD/CAM - international magazine of digital dentistry

08 I I special _ science & practice culty regenerating, such as the nervous tissue, whereas bone and blood, for instance, are consid- ered more suitable for stem cell therapy. In dentistry, pulp from primary teeth has been thoroughly investigated as a potential source of stem cells with promising results. However, the regeneration of an entire tooth, known as third dentition, is a highly complex process, which de- spitesomepromisingresultswithanimalsremains veryfarfromclinicalapplicability.Theoppositehas beenobservedintheareaofjawboneregeneration, where there is a higher level of scientific evidence for its clinical applications. Currently, adult stem cells have been harvested from bone marrow and fat, among other tissues. Bone marrow is haematopoietic, that is, capa- bleofproducingallthebloodcells.Sincethe1950s, when Nobel Prize winner Dr E. Donnall Thomas demonstrated the viability of bone marrow trans- plants in patients with leukaemia, many lives have been saved using this approach for a variety of immunological and haematopoietic 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 stemcells(whichwillbecomebone,muscleandfat tissues, for instance; Fig. 3). Bone marrow harvesting is carried out under local anaesthesia using an aspiration needle through the iliac (pelvic) bone. Other than requir- ingacompetentdoctortoperformsuchatask,itis not regarded as an excessively invasive or complex procedure. It is also not associated with high lev- els of discomfort either intra or post-operatively (Figs. 4a & b). Bone reconstruction is a challenge in dentistry (also in orthopaedics and oncology) because re- building bony defects caused by trauma, infec- tions, tumours or dental extractions requires bone grafting. The lack of bone in the jaws may impede the placement of dental implants, thus adversely affecting patients’ quality of life. In order to rem- edy bone scarcity, a bone graft is conventionally harvested from the chin region or the angle of the mandible. If the amount required is too large, bone from the skull, legs or pelvis may be used. Unliketheprocessforharvestingbonemarrow,the process involved in obtaining larger bone grafts is often associated with high levels of discom- fort and, occasionally, inevitable post-operative sequelae (Figs. 5a–e). The problems related to bone grafting have en- couraged the use of bone substitutes (synthetic materials and bone from human or bovine donors, for example). However, such materials show infe- riorresultscomparedwithautologousbonegrafts (from the patient himself/herself), since they lack autologous proteins. Therefore, in critical bony defects, that is, those requiring specific therapy to recover their original contour, a novel concept to avoid autologous grafting, involving the use of bone-sparing material combined with stem cells from the same patient, has been gaining ground as a more modern philosophy of treatment. Con- Fig. 11a_Bone marrow. Fig. 11b_Bone marrow transfer into a conic tube in a sterile environment (laminar flow). Fig. 11c_Bone marrow homogenisation in a buffer solution (laminar flow). Fig. 11d_Bone marrow combined with Ficoll (to aid cell separation). Fig. 11e_Pipette collection of the interface containing the mononuclear cells (where the stem cells are present). Fig. 11f_Second centrifuge spin. CAD/CAM 2_2013 Fig. 11d Fig. 11e Fig. 11f Fig. 11a Fig. 11b Fig. 11c