de Wild, Michael

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de Wild, Michael

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  • Vorschaubild nicht verfügbar
    Publikation
    Geometric cuts by an autonomous laser osteotome increase stability in mandibular reconstruction with free fibula grafts. A cadaver study
    (Elsevier, 2024) Gottsauner, Maximilian; Morawska, Marta M.; Tempel, Simon; Müller-Gerbl, Magdalena; Dalcanale, Federico; de Wild, Michael; Ettl, Tobias [in: Journal of Oral and Maxillofacial Surgery]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Geometric cuts by an autonomous laser osteotome increase stability in mandibular reconstruction with free fibula grafts. A cadaver study
    (Elsevier, 2024) Gottsauner, Maximilian; Morawska, Marta M.; Tempel, Simon; Müller-Gerbl, Magdalena; Dalcanale, Federico; de Wild, Michael; Ettl, Tobias [in: Journal of Oral and Maxillofacial Surgery]
    Background Nonunion and plate exposure represent a major complication after mandibular reconstruction with free fibula flaps. These drawbacks may be resolved by geometric osteotomies increasing intersegmental bone contact area and stability. Purpose The aim of this study was to compare intersegmental bone contact and stability of geometric osteotomies to straight osteotomies in mandibular reconstructions with free fibula grafts performed by robot-guided erbium-doped yttrium aluminum garnet laser osteotomy.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Parameter optimization in a finite element mandibular fracture fixation model using the design of experiments approach
    (Elsevier, 08/2023) Maintz, Michaela; Msallem, Bilal; de Wild, Michael; Seiler, Daniel; Herrmann, Sven; Feiler, Stefanie; Sharma, Neha; Dalcanale, Federico; Cattin, Philippe; Thieringer, Florian Markus [in: Journal of the Mechanical Behavior of Biomedical Materials]
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Effect of printing parameters on mechanical performance of material-extrusion 3D-printed PEEK specimens at the point-of-care
    (MDPI, 17.01.2023) Zarean, Paridokht; Zarean, Parichehr; de Wild, Michael; Thieringer, Florian M.; Sharma, Neha; Seiler, Daniel; Malgaroli, Patrick [in: Applied Sciences]
    Additive manufacturing (AM) of polyetheretherketone (PEEK) biomaterials using the material-extrusion (MEX) method has been studied for years. Because of the challenging manufacturing process, precisely controlling printing parameters is crucial. This study aimed to investigate the effects of printing parameters such as orientation and position of printing on mechanical properties. Thus, 34 samples were printed using PEEK filament and the MEX process. Samples were divided into two main groups (A,B) according to their printing orientations (A: groups 1–3) and positions on the build plate (B: groups 4–8). Mechanical tensile tests were performed to evaluate the effects of different printing orientations and positions on mechanical properties. The means of the tensile modulus in samples 3D-printed in XY (group 1), XZ (group 2), and ZX (group 3) orientations were not significantly different (p-value = 0.063). Groups 1 and 2 had smaller distributions than group 3 in the means of tensile strength. The t-test showed that the overall means of the measurements in groups 4–8 did not differ significantly (p-value = 0.315). The tensile tests indicated that printing in vertical and horizontal orientations had no significant influence on mechanical properties. There were no significant differences in mechanical strength between top/bottom printed samples in five different lateral positions. Reliability of printing with good mechanical properties could be a step forward to manufacturing patient-specific implants.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    3D-printed LEGO®-inspired titanium scaffolds for patient-specific regenerative medicine
    (Elsevier, 2023) Lee, Seunghun S.; Du, Xiaoyu; Smit, Thijs; Bissacco, Elisa G.; Seiler, Daniel; de Wild, Michael; Ferguson, Stephen J. [in: Biomaterials Advances]
    Despite the recent advances in 3D-printing, it is often difficult to fabricate implants that optimally fit a defect size or shape. There are some approaches to resolve this issue, such as patient-specific implant/scaffold designs based on CT images of the patients, however, this process is labor-intensive and costly. Especially in developing countries, affordable treatment options are required, while still not excluding these patient groups from potential material and manufacturing advances. Here, a selective laser melting (SLM) 3D-printing strategy was used to fabricate a hierarchical, LEGO®-inspired Assemblable Titanium Scaffold (ATS) system, which can be manually assembled in any shape or size with ease. A surgeon can quickly create a scaffold that would fit to the defect right before the implantation during the surgery. Additionally, the direct inclusion of micro- and macroporous structures via 3D-printing, as well as a double acid-etched surface treatment (ST) in the ATS, ensure biocompatibility, sufficient nutrient flow, cell migration and enhanced osteogenesis. Three different structures were designed (non-porous:NP, semi-porous:SP, ultra-porous:UP), 3D-printed with the SLM technique and then surface treated for the ST groups. After analyzing characteristics of the ATS such as printing quality, surface roughness and interconnected porosity, mechanical testing and finite element analysis (FEA) demonstrated that individual and stacked ATS have sufficient mechanical properties to withstand loading in a physiological system. All ATS showed high cell viability, and the SP and UP groups demonstrated enhanced cell proliferation rates compared to the NP group. Furthermore, we also verified that cells were well-attached and spread on the porous structures and successful cell migration between the ATS units was seen in the case of assemblies. The UP and SP groups exhibited higher calcium deposition and RT-qPCR proved higher osteogenic gene expression compared to NP group. Finally, we demonstrate a number of possible medical applications that reveal the potential of the ATS through assembly. © 2023 The Authors
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Immediate stabilization of pedicle screws
    (De Gruyter, 2023) de Wild, Michael; Zimmermann, Simon; Klein, Karina; Steffen, Thomas; Schlottig, Falko; Hasler, Carol; Rechenberg, Brigitte von [in: Current Directions in Biomedical Engineering]
    This study was designed as proof of principle and safety test of the novel technique, the Immediate Stabilization System (ISS). The technique is designed to immediately stabilize polymer-augmented pedicle screws (PAS) in deficient bone and avoid complications of loosening pedicle screws at the bone-screw interface, especially in osteoporotic patients. A polymer sleeve was designed as augmentation to improve screw anchorage after drilling the screw hole. By applying ultrasonic energy, the polymeric tube was molded into the pores of the host bone forming a strong and uniform bond with the adjacent bone. The original screw was then implanted into the denser bony environment leading to an enhanced immediate stability. The ISS-treated implants were compared to conventionally placed pedicle screws in ex-vivo cadaver bones (2 sheep spines, n = 6 implants per spine, total 12 screws) and in-vivo in a spinal sheep model (Swiss alpine sheep, n = 5, 4 implants per animal, total 20 screws). The primary stability of ISS-treated pedicle screws was increased in ex-vivo bone (+24% insertion torque (IT)) and in-vivo (+32.9% IT) in sheep spine. Removal torque (RT) was lower in the in PAS tested for 8 weeks in-vivo. The ISS technology demonstrated improved anchorage of pedicle screws in ex-vivo cadaver bones as well as in-vivo studies in sheep spine.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Three-dimensional printed hydroxyapatite bone substitutes designed by a novel periodic minimal surface algorithm are highly osteoconductive
    (Liebert, 2023) Maevskaia, Ekaterina; Khera, Nupur; Ghayor, Chafik; Bhattacharya, Indranil; Guerrero, Julien; Nicholls, Flora; Waldvogel, Christian; Bärtschi, Ralph; Fritschi, Lea; Salamon, Dániel; Özcan, Mutlu; Malgaroli, Patrick; Seiler, Daniel; de Wild, Michael; Weber, Franz E. [in: 3D Printing and Additive Manufacturing]
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Topology-optimized patient-specific osteosynthesis plates
    (De Gruyter, 02.09.2022) Maintz, Michaela; Seiler, Daniel; Thieringer, Florian M.; de Wild, Michael [in: Current Directions in Biomedical Engineering]
    Patient-specific osteosynthesis plates can be used to reduce complications related to bone fracture treatment, such as infection, malocclusion and fatigue fractures of plates and screws. However, the implant design process is tedious. We propose a semi-automatic workflow to computationally design patient-specific titanium osteosynthesis plates for mandibular angle fractures. In this process, the plate stiffness is maximized while the mass is reduced. Two plate designs with different numbers of screw holes (implant #1 with four holes, implant #2 with eight holes) were generated with identical topology optimization settings and compared in a finite element model simulating various biomechanical masticatory loads. Differences in von Mises stresses in the implants and screws were observed. The load case of clenching the jaw on the opposite side of the fracture showed the highest stress distribution in implant #1 and higher peak stresses in implant #2. Stress concentrations were observed in sharp corners of the implant and could be reduced using local stress-based topology optimization. We conclude that the design process is an effective method to generate patientspecific implants.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Characterization of a cotton-wool like composite bone graft material
    (Springer, 18.07.2022) Rohr, Nadja; Brunner, Claudia; Bellon, Benjamin; Fischer, Jens; de Wild, Michael [in: Journal of Materials Science: Materials in Medicine]
    Bone graft materials are applied in patients to augment bone defects and enable the insertion of an implant in its ideal position. However, the currently available augmentation materials do not meet the requirements of being completely resorbed and replaced by new bone within 3 to 6 months. A novel electrospun cotton-wool like material (Bonewool, Zurich Biomaterials LLC, Zurich, Switzerland) consisting of biodegradable poly(lactic-co-glycolic) acid (PLGA) fibers with incorporated amorphous ß-tricalcium phosphate (ß-TCP) nanoparticles has been compared to a frequently used bovine derived hydroxyapatite (Bio-Oss, Geistlich Pharma, Wolhusen, Switzerland) in vitro. The material composition was determined and the degradation behavior (calcium release and pH in different solutions) as well as bioactivity has been measured. Degradation behavior of PLGA/ß-TCP was generally more progressive than for Bio-Oss, indicating that this material is potentially completely resorbable.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Development of models for additively manufactured actuators using compliant Wren mechanism
    (Elsevier, 11/2021) Lennart, Rubbert; Schuler, Felix; Gayral, Thibault; de Wild, Michael; Renaud, Pierre [in: Precision Engineering]
    Compliant Wren mechanisms (CWM) constitute specific compliant structures of particular interest. Derived from Wren mechanisms, they can exhibit a large variety of motions, from quasi translation to quasi rotation. In this paper, the development of models for the analysis and synthesis of CWM is considered. A kinematic model is introduced first to assess all possible motions when used as an actuator. Then the static model and stress expressions are derived to help their design. These derivations are achieved for two types of geometries, corresponding to the geometries of interest. CWM are filigree structures, whose manufacturing is difficult to consider without additive manufacturing. A specific work on their production using selective laser melting (SLM) is then achieved to ensure the reliability of their production. As a proof of concept, a pneumatically actuated component is then developed and tested. It is composed of two CWM of different geometries. It offers the possibility to obtain translation and rotation using a single pressure input. The developed models are investigated using finite element models and experiments using additively manufactured structures.
    01A - Beitrag in wissenschaftlicher Zeitschrift