Biofunctional Glycol-Modified Polyethylene Terephthalate and Thermoplastic Polyurethane Implants by Extrusion-Based Additive Manufacturing for Medical 3D Maxillofacial Defect Reconstruction

This work addresses the topic of extrusion-based additive manufacturing (filament-based material extrusion) of patient-specific biofunctional maxillofacial implants. The technical approach was chosen to overcome the shortcomings of medically established fabrication processes such as a limited availability of materials or long manufacturing times. The goal of the work was a successful fabrication of basic implants for defect reconstruction. The underlying vision is the implants’ clinic-internal and operation-accompanying application. Following a literature search, a material selection was conducted. Digitally prepared three-dimensional (3D) models dealing with two representative mandible bone defects were printed based on the material selection. An ex-vivo model of the implant environment evaluated dimensional and fitting traits of the implants. Glycol-modified PET (PETG) and thermoplastic polyurethane (TPU) were finally selected. These plastics had high cell acceptance, good mechanical properties, and optimal printability. The subsequent fabrication process yielded two different implant strategies: the standard implant made of PETG with a build-up rate of approximately 10 g/h, and the biofunctional performance implant with a TPU shell and a PETG core with a build-up rate of approximately 4 g/h. The standard implant is meant to be intraoperatively applied, as the print time is below three hours even for larger skull defects. Standard implants proved to be well fitting, mechanically stable and cleanly printed. In addition, the hybrid implant showed particularly cell-friendly behavior due to the chemical constitution of the TPU shell and great impact stability because of the crack-absorbing TPU/PETG combination. This biofunctional constellation could be used in specific reconstructive patient cases and is suitable for pre-operative manufacturing based on radiological image scans of the defect. In summary, filament-based material extrusion has been identified as a suitable manufacturing method for personalized implants in the maxillofacial area. A further clinical and mechanical study is recommended.

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A mini-review of embedded 3D printing: supporting media and strategies

Journal of Materials Chemistry B ◽

10.1039/d0tb01819h ◽

2020 ◽

Vol 8 (46) ◽

pp. 10474-10486

Author(s):

Jingzhou Zhao ◽

Nongyue He

Keyword(s):

Additive Manufacturing ◽

3D Printing ◽

Manufacturing Method ◽

Material Extrusion

Embedded 3D printing is an additive manufacturing method based on a material extrusion strategy.

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Effect of Printing Temperature on Mechanical and Viscoelastic Properties of Ultra-flexible Thermoplastic Polyurethane in Material Extrusion Additive Manufacturing

Journal of Materials Engineering and Performance ◽

10.1007/s11665-021-06510-9 ◽

2022 ◽

Author(s):

Omer Yunus Gumus ◽

Recep Ilhan ◽

Berat Enes Canli

Keyword(s):

Additive Manufacturing ◽

Viscoelastic Properties ◽

Thermoplastic Polyurethane ◽

Material Extrusion

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Study of the interlayer adhesion and warping during material extrusion-based additive manufacturing of a carbon nanotube/biobased thermoplastic polyurethane nanocomposite

Polymer ◽

10.1016/j.polymer.2021.123734 ◽

2021 ◽

pp. 123734

Author(s):

María Virginia Candal ◽

Itxaso Calafel ◽

Mercedes Fernández ◽

Nora Aranburu ◽

Roberto Hernández Aguirresarobe ◽

...

Keyword(s):

Carbon Nanotube ◽

Additive Manufacturing ◽

Thermoplastic Polyurethane ◽

Material Extrusion

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3D Printed Multi-material Medical Phantoms for Needle-tissue Interaction Modelling of Heterogeneous Structures

Journal of Bionic Engineering ◽

10.1007/s42235-021-0031-1 ◽

2021 ◽

Vol 18 (2) ◽

pp. 346-360

Author(s):

Jun Yin ◽

Manqi Li ◽

Guangli Dai ◽

Hongzhao Zhou ◽

Liang Ma ◽

...

Keyword(s):

Mechanical Properties ◽

Soft Tissue ◽

Medical Training ◽

Thermoplastic Polyurethane ◽

Acrylonitrile Butadiene Styrene ◽

Tactile Feedback ◽

Patient Specific ◽

Insertion Force ◽

Silicone Grease ◽

Manufacturing Method

AbstractThe fabrication of multi-material medical phantoms with both patient-specificity and realistic mechanical properties is of great importance for the development of surgical planning and medical training. In this work, a 3D multi-material printing system for medical phantom manufacturing was developed. Rigid and elastomeric materials are firstly combined in such application for an accurate tactile feedback. The phantom is designed with multiple layers, where silicone ink, Thermoplastic Polyurethane (TPU), and Acrylonitrile Butadiene Styrene (ABS) were chosen as printing materials for skin, soft tissue, and bone, respectively. Then, the printed phantoms were utilized for the investigation of needle-phantom interaction by needle insertion experiments. The mechanical needle-phantom interaction was characterized by skin-soft tissue interfacial puncture force, puncture depth, and number of insertion force peaks. The experiments demonstrated that the manufacturing conditions, i.e. the silicone grease ratio, interfacial thickness and the infill rate, played effective roles in regulating mechanical needle-phantom interaction. Moreover, the influences of material properties, including interfacial thickness and ultimate stress, on needle-phantom interaction were studied by finite element simulation. Also, a patient-specific forearm phantom was printed, where the anatomical features were acquired from Computed Tomography (CT) data. This study provided a potential manufacturing method for multi-material medical phantoms with tunable mechanical properties and offered guidelines for better phantom design.

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OP11 Exposure to an inflammatory mix re-induces inflammation in organoids of ulcerative colitis patients, independent of the inflammatory state of the tissue of origin

Journal of Crohn s and Colitis ◽

10.1093/ecco-jcc/jjz203.010 ◽

2020 ◽

Vol 14 (Supplement_1) ◽

pp. S011-S012

Author(s):

K Arnauts ◽

B Verstockt ◽

J Sabino ◽

S Vermeire ◽

C Verfaillie ◽

...

Keyword(s):

Ulcerative Colitis ◽

Transcriptional Activation ◽

Ex Vivo ◽

Principal Component ◽

Patient Specific ◽

Ex Vivo Model ◽

Mayo Score ◽

Ex Vivo Culture ◽

Different Response

Abstract Background Patient-derived intestinal organoids provide a powerful tool to unravel mechanisms underlying inflammatory bowel disease (IBD). Recently, we showed that organoids derived from inflamed regions in ulcerative colitis (UC) patients lose their inflammatory phenotype during ex vivo culture and were indistinguishable from organoids of non-inflamed regions in these patients.1 To study UC in an ex vivo model, we hypothesised that inflammation should be re-induced towards levels corresponding to the in vivo situation. In addition, we aimed to elucidate if organoids derived from inflamed regions are more sensitive towards inflammatory stimulation, compared with organoids from non-inflamed regions of UC patients and non-IBD controls. Methods Biopsies were obtained from 8 patients with active UC (endoscopic Mayo score of ≥2), both in inflamed and non-inflamed regions, and in 8 non-IBD controls. Crypts were isolated and cultured as organoids for at least four weeks. Organoids were subjected to a predefined inflammatory mix (MIX: 100 ng/ml TNF-α, 20 ng/ml IL-1β, 1 µg/ml Flagellin) or medium only (CTRL) for 24 h (Figure 1). RNA was extracted from organoids for RNA sequencing by Lexogen QuantSeq for Illumina. Differential gene expression and pathways were studied through DESeq2 and ingenuity pathway analysis (false discovery rate <0.05). Results Prior to inflammatory stimulation, principal component analysis (PCA) demonstrated separate clustering between organoids derived from non-IBD controls and UC patients. Exposure to the inflammatory mix induced transcriptional activation of inflammatory genes (CXCL1, DUOXA2, IL1β, IL8, IL23α, etc., all p < 0.001) and pathways in all conditions (Figure 2). However, organoids of non-IBD controls clustered separate from organoids of UC patients. Within organoids of UC patients (inflamed vs. non-inflamed origin), we observed no differentially expressed genes after inflammatory stimulation but organoids clustered per patient instead (Figure 3). Inflammatory markers in UC organoids reached transcriptional expression levels (CXCL1, CXCL2, IFNGR1, IL1β, DUOXA2, etc.) and activated pathways (antigen presentation, interferon signalling, granulocyte adhesion and diapedesis) similar to those observed in crypts derived from inflamed biopsies. Conclusion Inflammation can efficiently be (re-)induced in organoids from both UC and non-IBD origin. However, a different response was observed between organoids of non-IBD and UC origin. Of note, in UC organoids, the state of inflammation in the source tissue was irrelevant. In conclusion, we showed that it is essential to re-induce inflammation in patient-specific organoids, but there is no need to obtain biopsies from inflamed regions. Reference

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Indirect Additive Manufacturing Processing of Poly-Lactide-co-Glycolide

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.754-755.985 ◽

2015 ◽

Vol 754-755 ◽

pp. 985-989

Author(s):

Shah Fenner Khan ◽

M.J. German ◽

K.W. Dalgarno

Keyword(s):

Additive Manufacturing ◽

Constant Pressure ◽

Research Work ◽

Mechanical Tests ◽

Patient Specific ◽

Manufacturing Method ◽

Post Surgery ◽

Fixation Plate ◽

New Treatments ◽

Specific Fracture

The research and development of biomaterials have brought about new treatments in regenerative medicine. The research work presented in this paper focus on the use of Poly-Lactide-co-glycolide (PLGA) in the fabrication of patient specific fracture fixation plate by indirect additive manufacturing method. The use of biopolymers such as PLGA has been seen as a solution to the problems of stress shield and post-surgery inherent in biometal fixation plates. This paper discusses the consequence of this processing method on characteristics and properties of the PLGA. PLGA of ratio 50:50, 65:35 and 85:15 was processed and compared. The granules of PLGA were positioned in the cavity of the stereolithography (SLA) mould and heated under constant pressure with sintering temperature of 73°C for 2.0hours. Both the variation in samples fabricated from this process with the designed model and the changes in material characteristics are below 10%. The flexural strength for PLGA of ratio 50:50, 65:35 and 85:15 is 73.8±2.3MPa, 75.0±2.8, 60.0±11.7, respectively. The characteristics and mechanical tests indicate that the results were comparable with conventional processing of PLGA.

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Viscoelastic Behaviour of Flexible Thermoplastic Polyurethane Additively Manufactured Parts: Influence of Inner-Structure Design Factors

Polymers ◽

10.3390/polym13142365 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2365

Author(s):

Fernández Pelayo ◽

David Blanco ◽

Pedro Fernández ◽

Javier González ◽

Natalia Beltrán

Keyword(s):

Additive Manufacturing ◽

Mechanical Behaviour ◽

Flexible Electronics ◽

Thermoplastic Polyurethane ◽

Relaxation Modulus ◽

Maxwell Model ◽

Material Model ◽

Structure Design ◽

Material Extrusion ◽

Design Factors

Material extrusion based additive manufacturing is used to make three dimensional parts by means of layer-upon-layer deposition. There is a growing variety of polymers that can be processed with material extrusion. Thermoplastic polyurethanes allow manufacturing flexible parts that can be used in soft robotics, wearables and flexible electronics applications. Moreover, these flexible materials also present a certain degree of viscoelasticity. One of the main drawbacks of material extrusion is that decisions related to specific manufacturing configurations, such as the inner-structure design, shall affect the final mechanical behaviour of the flexible part. In this study, the influence of inner-structure design factors upon the viscoelastic relaxation modulus, E(t), of polyurethane parts is firstly analysed. The obtained results indicate that wall thickness has a higher influence upon E(t) than other inner-design factors. Moreover, an inadequate combination of those factors could reduce E(t) to a small fraction of that expected for an equivalent moulded part. Next, a viscoelastic material model is proposed and implemented using finite element modelling. This model is based on a generalized Maxwell model and contemplates the inner-structure design. The results show the viability of this approach to model the mechanical behaviour of parts manufactured with material extrusion additive manufacturing.

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