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Publikation Osteoconductive Lattice Microarchitecture for Optimized Bone Regeneration(Mary Ann Liebert, 06/2018) de Wild, Michael; Ghayor, Chafik; Zimmermann, Simon; Rüegg, Jasmine; Nicholls, Flora; Schuler, Felix; Chen, Tse-Hsiang; Weber, Franz E.Selective laser melting (SLM) is one methodology to realize additive manufacturing and is mainly used to join metal powder in a layer-by-layer manner to produce a solid three-dimensional (3D) object. For bone tissue engineering purposes, scaffolds can readily be designed as 3D data model and realized with titanium known for its excellent osseointegration behavior. The microarchitecture, that is, design with submillimeter features, of additively manufactured scaffolds is in many cases a lattice structure. This study aimed to apply SLM that allows a high degree of microarchitectural freedom to generate lattice structures and to determine the optimal distance between rods and the optimal diameter of rods for osteoconduction (bone ingrowth into scaffolds) and bone regeneration. For the biological readout, diverse SLM-fabricated titanium implants were placed in the calvarium of rabbits and new bone formation and defect bridging were determined after 4 weeks of healing. The results from the middle section of the defects show that with a lattice microarchitecture, the optimal distance between titanium rods is around 0.8 mm and the optimal rod dimension is between 0.3 and 0.4 mm to optimize defect bridging and bone regeneration.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Marker for the pre-clinical development of bone substitute materials(De Gruyter, 2017) de Wild, Michael; Zimmermann, Simon; Obrecht, Marcel; Dard, MichelThin mechanically stable Ti-cages have been developed for the in-vivo application as X-ray and histology markers for the optimized evaluation of pre-clinical performance of bone graft materials. A metallic frame defines the region of interest during histological investigations and supports the identification of the defect site. This standardization of the procedure enhances the quality of pre-clinical experiments. Different models of thin metallic frameworks were designed and produced out of titanium by additive manufacturing (Selective Laser Melting). The productibility, the mechanical stability, the handling and suitability of several frame geometries were tested during surgery in artificial and in ex-vivo bone before a series of cages was preclinically investigated in the female Göttingen minipigs model. With our novel approach, a flexible process was established that can be adapted to the requirements of any specific animal model and bone graft testing.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Influence of microarchitecture on osteoconduction and mechanics of porous titanium scaffolds generated by selective laser melting(Mary Ann Liebert, 2016) de Wild, Michael; Zimmermann, Simon; Rüegg, Jasmine; Schumacher, Ralf; Fleischmann, Thea; Ghayor, Chafik; Weber, Franz E.Bone regeneration is naturally based on bone forming cells, osteoinduction by diverse growth factors, and osteoconduction. The latter one used as term in this study is the ingrowth of bone in 3D structures, which leads to an optimal case in creeping substitution of the scaffold by newly formed bone. Autologous bone is still the gold standard for bone substitutes. In most cases, newly developed bone substitutes consist of calcium phosphate, since hydroxyapatite is the main component of bone and mimics cancellous bone in microstructure. In this study, we wanted to elucidate the optimal microarchitecture for osteoconduction and determine compression strength and Young’s Modulus of the selected architectures. Selective laser melting of titanium was used as tool to generate diverse architectures in a repetitive and precise way. To link 3D scaffold architecture to biological readouts, bone ingrowth, bone to implant contact, and defect bridging of noncritical-sized defects in the calvarial bone of rabbits were determined. In this series, 5 different microarchitectures were tested with pore sizes ranging from 700 to 1300 lm and constrictions between 290 and 700 lm. To our surprise, all microstructures showed the same biological response of excellent osteoconduction. However, the mechanical yield strength of these structures differed by the factor of three and reached up to three times the strength of cancellous bone at a porosity of 72.3–88.4%. These results suggest that the microarchitecture of bone substitutes can be optimized toward mechanical strength in a wide range of constrictions and pore sizes without having a negative influence on osteoconduction.01A - Beitrag in wissenschaftlicher Zeitschrift