TY - JOUR A1 - Rack, A. A1 - Rack, T. A1 - Stiller, M. A1 - Riesemeier, Heinrich A1 - Zabler, S. A1 - Nelson, K. T1 - In vitro synchrotron-based radiography of micro-gap formation at the implant-abutment interface of two-piece dental implants N2 - Micro-gap formation at the implant-abutment interface of two-piece dental implants was investigated in vitro using high-resolution radiography in combination with hard X-ray synchrotron radiation. Images were taken with the specimen under different mechanical loads of up to 100 N. The aim of this investigation was to prove the existence of micro-gaps for implants with conical connections as well as to study the mechanical behavior of the mating zone of conical implants during loading. Synchrotron-based radiography in comparison with classical laboratory radiography yields high spatial resolution in combination with high contrast even when exploiting micro-sized features in highly attenuating objects. The first illustration of a micro-gap which was previously indistinguishable by laboratory methods underlines that the complex micro-mechanical behavior of implants requires further in vitro investigations where synchrotron-based micro-imaging is one of the prerequisites. KW - X-ray imaging KW - Dental implants KW - Digital radiography KW - Implant-abutment interface PY - 2010 DO - https://doi.org/10.1107/S0909049510001834 SN - 0909-0495 SN - 1600-5775 VL - 17 IS - 2 SP - 289 EP - 294 PB - Blackwell Publishing CY - Oxford AN - OPUS4-22121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gildenhaar, Renate A1 - Berger, Georg A1 - Lehmann, Erhard A1 - Stiller, M. A1 - Koch, C. A1 - Ducheyne, P. A1 - Rack, A. A1 - Seligmann, H. A1 - Jonscher, S. A1 - Knabe, C. T1 - A comparative study of the biodegradability of calcium-alkali-orthophosphate ceramics in vitro and in vivo KW - Calcium-alkali-orthophosphate KW - Solubility KW - Biodegradability PY - 2007 SN - 1013-9826 VL - 330-332 SP - 63 EP - 66 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-14528 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Knabe, C. A1 - Houshmand, A. A1 - Berger, Georg A1 - Ducheyne, P. A1 - Gildenhaar, Renate A1 - Kranz, I. A1 - Stiller, M. T1 - Effect of rapidly resorbable bone substitute materials on the temporal expression of the osteoblastic phenotype in vitro N2 - 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 β-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. KW - Bone substitute materials KW - Calcium-alkali-orthophosphate ceramics KW - SaOS-2 cells KW - Osteoblast differentiation KW - Bioactive glass PY - 2008 DO - https://doi.org/10.1002/jbm.a.31383 SN - 1549-3296 SN - 1552-4965 VL - 84A IS - 4 SP - 856 EP - 868 PB - Wiley CY - Hoboken, NJ AN - OPUS4-16658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dombrowski, Felix A1 - Marx, Heidi A1 - Ploska, Ute A1 - Nicolaides, Dagmar A1 - Stiller, M. A1 - Knabe, C. A1 - Berger, Georg T1 - Solubility and ingrowth behaviour of degradable and figuline calcium alkaline phosphate cements N2 - The thrust of the investigations presented here is to point out the degradation behaviour in vitro and the ingrowth behaviour in vivo of four different calcium alkaline phosphate cements. Two of the figuline and mouldable composites consist of the crystalline phase Ca2KNa(PO4)2 and two of the crystalline phase Ca10[K/Na](PO4)2 each containing 2wt% medium gel strength porcine gelatin. Furthermore A-TCP was added to both Ca10[K/Na](PO4)2 cements as a hardening supporting reactant. The testing material groups differ in small amorphous portions containing either silica phosphate (GB9), magnesium potassium phosphate (GB14) or diphosphates (401545 and 401545(70)). The respective composites show a monomodal particle size distribution (d50~7µm; span~4) and an average total porosity around 28vol%.For the solubility studies cylindrical samples (d=6mm; h=12mm) were stored in a 0.1mol TRIS buffer solution and incubated at 37°C for maximum 50 weeks. The storage solution was analysed and renewed every week. The results are plotted cumulative. For the in vivo studies critical size defects were dissected to mandibles in a sheep model in which a 1cm³ area of the bottom of the mandibles was surgically resected and replaced with the figuline cements whereas the mouldability allows the reconstruction of the original outer contour without draining off even when replacing upside down. KW - Calcium alkaline phosphate cement KW - Gelatin KW - Figuline KW - Solubility KW - Ingrowth behavior PY - 2012 DO - https://doi.org/10.4028/www.scientific.net/KEM.493-494.387 SN - 1013-9826 VL - 493-494 SP - 387 EP - 390 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-24924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rack, T. A1 - Zabler, S. A1 - Rack, C. A1 - Stiller, M. A1 - Riesemeier, Heinrich A1 - Cecilia, A. A1 - Nelson, K. T1 - Coherent synchrotron-based micro-imaging employed for studies of micro-gap formation in dental implants N2 - Biocompatible materials such as titanium are regularly applied in oral surgery. Titanium-based implants for the replacement of missing teeth demand a high mechanical precision in order to minimize micro-bacterial leakage, especially when two-piece concepts are used. Synchrotron-based hard x-ray radiography, unlike conventional laboratory radiography, allows high spatial resolution in combination with high contrast even when micro-sized features in such highly attenuating objects are visualized. Therefore, micro-gap formation at interfaces in two-piece dental implants with the sample under different mechanical loads can be studied. We show the existence of micro-gaps in implants with conical connections and study the mechanical behavior of the mating zone of conical implants during loading. The micro-gap is a potential source of implant failure, i.e., bacterial leakage, which can be a stimulus for an inflammatory process. T2 - 10th International conference on X-ray microscopy CY - Chicago, Illinois, USA DA - 15.08.2010 KW - X-ray imaging KW - Dental implants KW - Digital radiography KW - Implant-abutment interface KW - Synchrotron radiation KW - X-ray phase contrast PY - 2011 SN - 978-0-7354-0925-5 DO - https://doi.org/10.1063/1.3625398 N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings VL - 1365 SP - 445 EP - 448 AN - OPUS4-25347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Rack, A. A1 - Zabler, S. A1 - Riesemeier, Heinrich A1 - Weidemann, Gerd A1 - Müller, Bernd R. A1 - Helfen, L. A1 - Stiller, M. A1 - Knabe, C. A1 - Goebbels, Jürgen A1 - Banhart, J. T1 - Nondestructive 3D insights into foamy metals and bioregenerative ceramics KW - X-ray Computed Tomography KW - Metal foams KW - Bioregenerative ceramics PY - 2008 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/infos/bessy/highlights2007.pdf#page=34 SN - 1611-6127 SP - 34 EP - 35 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-17538 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -