Effect of rapidly resorbable bone substitute materials on the temporal expression of the osteoblastic phenotype \u3cem\u3ein vitro\u3c/em\u3e

Ideally, bioactive ceramics for use in alveolar ridge augmentation should possess the ability to activate bone formation and, thus, cause the differentiation of osteoprogenitor cells into osteoblasts at their surfaces. Therefore, in order to evaluate the osteogenic potential of novel bone substitute materials, it is important to examine their effect on osteoblastic differentiation. This study examines the effect of rapidly resorbable calcium–alkali– orthophosphates on osteoblastic phenotype expression and compares this behavior to that of ß-tricalcium phosphate (TCP) and bioactive glass 45S5. Test materials were three materials (denominated GB14, GB9, GB9/25) with a crystalline phase Ca2KNa(PO4)2 and with a small amorphous portion containing either magnesium potassium phosphate (GB14) or silica phosphate (GB9 and GB9/25, which also contains Ca2P2O7); and a material with a novel crystalline phase Ca10[K/Na](PO4)7 (material denominated 352i). SaOS-2 human bone cells were grown on the substrata for 3, 7, 14, and 21 days, counted, and probed for an array of osteogenic markers. GB9 had the greatest stimulatory effect on osteoblastic proliferation and differentiation, suggesting that this material possesses the highest potency to enhance osteogenesis. GB14 and 352i supported osteoblast differentiation to the same or a higher degree than TCP, whereas, similar to bioactive glass 45S5, GB9/25 displayed a greater stimulatory effect on osteoblastic phenotype expression, indicating that GB9/25 is also an excellent material for promoting osteogenesis

Structural and spectroscopic characterization of a series of potassium-and/or sodium-substituted beta-tricalcium phosphate

International audienceIn this paper, we report X-ray diffraction investigations as well as Raman and solid-state (31)P and (23)Na magic angle spinning nuclear magnetic resonance (NMR) characterization of three series of calcium orthophosphates. The general formulae of the studied compounds are Ca(10.5-x/2)M(x)(PO(4))(7), where M=K or Na and x=0, 0.25, 0.50, 0.75, 1.0; and Ca(10)K(x)Na(1-x)(PO(4))(7), where x=0, 0.25, 0.5, 0.75, 1.0. These calcium orthophosphates are found to be isostructural with β-tricalcium phosphate (β-TCP, Ca(3)(PO(4))(2)) with the substitution of some calcium sites by potassium and/or sodium cations. The unit cell parameters vary continuously with the level of substitution, a characteristic of these solid solutions. The Raman spectra show the different vibrational bands of the phosphate groups PO(4), while the NMR chemical shifts are sensitive to the non-equivalent phosphorus and sodium ions present in these substituted samples. As both Raman and NMR spectroscopies are local probes, they offer tools to distinguish between these different phosphorus and phosphate groups, according to their structural site and local environment, especially the type of cation substituent. A convenient decomposition of the Raman and NMR spectra into Gaussian-Lorentzian components leads us to propose an assignment of the main observed bands of these substituted β-TCPs

Resorbierbare Glaskeramik mit kontrolliertem Aufloesungsvermoegen Abschlussbericht

For the development of rapidly resorbable, long-term stable bioactive glass ceramics as new implant materials, the system CaO-P_2O_5-K_2O-Na_2O-MgO(-SiO_2) has been reinvestigated. Starting from CaNaPO_4, glassy-crystalline materials of higher solubility than hydroxylapatite and #alpha#-tricalcit phosphate have been obtained. As main phases Ca_4MgNa_5(PO_4)_5, MgKPO_4 and Ca_2KNa(PO_4)_2 have been isolated and characterized. Solubility rates of the materials were determined by screening tests. Biological compatibility was tested in vitro as well as in vivo experiments. (WEN)SIGLEAvailable from TIB Hannover: F96B441+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Bioceramics composition modulate resorption of human osteoclasts

Biomaterials used in bone regeneration are designed to be gradually resorbed by the osteoclast and replaced by new bone formed through osteoblastic activity. The aim of the present study is to analyze the role of osteoclasts in the resorption process. The attachment of human osteoclasts and the appearance of their resorption lacunae, when cultured on either the resorbable crystalline, calcium orthophosphate materials or on the long-term stable bioceramic material was investigated. The resorbable materials contain Ca10[K,Na](PO4)7 (AW-Si) and Ca2KNa(PO4)2 (GB14, GB9 & D9/25) as their main crystal phases, however they differ in their total solubility. These differences result from small variations in the composition. The long-term stable material consist of about 30% fluorapatite beside calcium zirconium phosphate (Ca5(PO4)3F + CaZr4(PO4)6) and shows a very small solubility. AW-Si has an alkali containing crystalline phase, Ca10[K,Na](PO4). While GB14, GB9 and D9/25 contain the crystalline phase Ca2KNa(PO4)2 with small additions of crystalline and amorphous diphosphates and/or magnesium potassium phosphate (GB14). D9/25 and AW-Si is less soluble compared to GB14, and GB9 among the resorbable materials. Resorbable and long-term stable materials vary in their chemical compositions, solubility, and surface morphology. Osteoclasts modified the surface in their attempts to resorb the materials irrespective of the differences in their physical and chemical properties. The depth and morphology of the resorption imprints were different depending on the type of material. These changes in the surface structure created by osteoclasts are likely to affect the way osteoblasts interact with the materials and how bone is subsequently formed.Y. Ramaswamy, D. R. Haynes, G. Berger, R. Gildenhaar, H. Lucas, C. Holding and H. Zreiqa