The Fifth Asian Indoor and Martial Arts Games in Turkmenistan - A dentist's perspective.

This article is a personal view of two dentists who were invited to attend the recent Fifth Asian World Indoor and Martial Arts Championships in Ashgabat, Turkmenistan. We relate the issues of getting to the venue, challenges during our stay and the role of the dentist in the sporting arena.

Immediate reconstruction of massive cranio-orbito-facial defects with allogeneic and alloplastic matrices in baboons.

40 cranio-orbito-facial osseous defects were created in 20 adult male baboons (Papio ursinus) to test the effectiveness of an allogeneic and an alloplastic matrix implant for the functional and morphological repair of the disassembled craniofacial complex. In each animal, one defect was reconstructed with a craniofacial bone segment harvested from donor adult baboons, and processed so as to obtain autolysed antigen-extracted allogeneic (AAA) bone matrix, preserving the bone morphogenetic protein (BMP) activity essential for bone induction. The contralateral defect was implanted with spherical macrobeads of polymethylmethacrylate (PMMA) coated with poly-2-hydroxyethylmethacrylate (PHEMA), and sintered into a porous molded implant, replicating the structural anatomy of the avulsed osseous segment. Histological analysis was carried out on undecalcified and decalcified bone sections prepared from specimens harvested at 3, 6 and 12 months after surgery. In AAA bone, the morphogenetic response was characterized by vascular invasion and mesenchymal cell aggregation after partial resorption of the implanted matrix. This was followed by bone deposition at the osteotomy interfaces and within the medullary spaces of the implanted AAA bone. Although bone ingrowth did occur in some PMMA/PHEMA specimens, the majority of implants showed fibrous union at the recipient interfaces. The limited bone ingrowth may be related to narrow interconnections between larger porous spaces after chemical synthesis of the two polymeric components. Osteogenesis in AAA bone appeared consistent with osteoconductive invasion from the viable bone at the recipient interfaces. In addition, the finding of a delicate trabecular-like bone, appositional to the central areas of the implanted matrix, suggests bone formation by induction.

Primate dentine extracellular matrix induces bone differentiation in heterotopic sites of the baboon (Papio ursinus).

In rodents, demineralized dentine matrix induces local differentiation of endochondral bone. This study investigated the osteoinductive potential of primate dentine matrices when implanted extraskeletally in allogeneic recipients. Demineralized dentine cylinders prepared from adult baboon incisors and demineralized dentine matrix pulverized to a particle size of 74-420 microns were implanted into the rectus abdominis of 4 subadult male baboons (Papio ursinus). Specimens were harvested 30 and 90 d after implantation. Histological analysis on serial sections showed bone differentiation in demineralized dentine cylinders after partial resorption of the external demineralized layer, and in resorption lacunae and excavation chambers within the matrix. Implants of demineralized dentine matrix of 74-420 microns particle size showed no osteoinductive activity as determined biochemically (alkaline phosphatase activity) and histologically. The demonstration of bone induction by primate dentine prepared from fully erupted tooth matrix suggests that putative osteogenic proteins may be conserved after dentinogenesis and embryonic tooth development, and may play a role during healing after surface demineralization of exposed root surfaces during regenerative procedures in humans.

Xenogeneic osteogenin, a bone morphogenetic protein, and demineralized bone matrices, including human, induce bone differentiation in athymic rats and baboons.

Subcutaneous implantation of xenogeneic demineralized bone matrix does not initiate endochondral bone differentiation. Dissociative extraction in 4 M guanidine-HCl or 6 M urea has shown that the apparent species-specificity of intact bone matrix resides in its insoluble immunogenic component, since there is homology in solubilized osteogenic proteins amongst mammals. To further investigate the species-specificity and cross-species reactivity of bone matrix components, baboon and human demineralized bone matrix (DBM) and bovine osteogenin, purified greater than 50,000-fold and with an apparent molecular mass of 28-42 kilodaltons, were implanted in the subcutaneous space of athymic and euthymic rats and into the rectus abdominis of 16 baboons (Papio ursinus). Baboon DBM was also implanted in athymic and euthymic mice. Alkaline phosphatase activity and histology of implants harvested at day 11 and 30 showed that baboon and human DBM induced endochondral bone differentiation both in athymic rats and baboons. Bovine osteogenin in conjunction with baboon insoluble collagenous matrix induced extensive bone differentiation in athymic rats and baboons. Baboon and human DBM did not induce bone differentiation in euthymic rats and, in athymic mice, baboon DBM failed to induce bone differentiation, determining instead the recruitment of multinucleated giant cells. The results indicate that in rodents bone differentiation induced by intact bone matrix is species specific and that T-cell functions are not a requirement for bone induction, although immunologically competent rats block bone differentiation from xenogeneic matrix. Bone differentiation induced by human DBM in baboons suggests that intact bone matrices may not be species-specific amongst primates.(ABSTRACT TRUNCATED AT 250 WORDS)