The Role of 3D Printing in Medical Applications: A State of the Art. J Healthc Eng. 2019;2019:5340616. [PMID: 31019667 PMCID: PMC6451800 DOI: 10.1155/2019/5340616]

Aplicação da tecnologia de impressão 3D no tratamento da pseudartrose da fratura de Hoffa*

Objetivo Avaliar uma proposta de processo de impressão tridimensional (3D) de um biomodelo preparado com o auxílio da tecnologia de modelagem por deposição de material fundido (fused deposition modeling, FDM, em inglês) a partir de imagens de tomografia computadorizada (TC) de um indivíduo com pseudartrose de fratura coronal do côndilo femoral (fratura de Hoffa).

Materiais e Métodos Para tanto, utilizamos imagens de TC, que permitem estudar a reconstrução volumétrica 3D do modelo anatômico, além da arquitetura e geometria óssea de sítios de anatomia complexa, como as articulações. Também permite o planejamento cirúrgico virtual (PCV) em um programa de desenho assistido por computador (computer-aided design, CAD, em inglês). Essa tecnologia possibilita a impressão de modelos anatômicos em escala real que podem ser utilizados em simulações cirúrgicas para o treinamento e a escolha do melhor posicionamento do implante de acordo com o PCV. Na avaliação radiográfica da osteossíntese da pseudartrose de Hoffa, verificou-se a posição do implante no modelo anatômico impresso em 3D e no joelho do paciente.

Resultados O modelo anatômico impresso em 3D apresentou características geométricas e morfológicas semelhantes às do osso real. O posicionamento dos implantes em relação à linha de pseudartrose e pontos anatômicos foram bastante precisos na comparação do joelho do paciente com o modelo anatômico impresso em 3D.

Conclusão A utilização do modelo anatômico virtual e do modelo anatômico impresso em 3D com a tecnologia de manufatura aditiva (MA) foi eficaz e auxiliou o planejamento e a realização do tratamento cirúrgico da pseudartrose da fratura de Hoffa. Desta forma, foi bastante preciso na reprodutibilidade do planejamento cirúrgico tanto virtual quanto no modelo anatômico impresso em 3D.

Feasibility and safety of a novel 3D-printed biodegradable biliary stent in an in vivo porcine model: a preliminary study

To assess the feasibility and safety of a novel 3D-printed biodegradable biliary stent using polycaprolactone (PCL) in an in vivo porcine model. In this animal study using domestic pigs, biodegradable radiopaque biliary stents made of polycaprolactone (PCL) and barium sulfate were produced using 3D printing and surgically inserted into the common bile duct (CBD) of pigs (stent group, n = 12). Another five pigs were allocated to the control group that only underwent resection and anastomosis of the CBD without stent insertion. To check the position and status of the stents and stent-related complications, follow-up computed tomography (CT) was performed every month. The pigs were sacrificed 1 or 3 months after surgery, and their excised CBD specimens were examined at both the macroscopic and microscopic levels. Three pigs (one in the stent group and two in the control group) died within one day after surgery and were excluded from further analysis; the remaining 11 in the stent group and 3 in the control group survived the scheduled follow-up period (1 month, 5 and 1; and 3 months, 6 and 2 in stent and control groups, respectively). In all pigs, no clinical symptoms or radiologic evidence of biliary complications was observed. In the stent group (n = 11), stent migration (n = 1 at 3 months; n = 2 at 1 month) and stent fracture (n = 3 at 2 months) were detected on CT scans. Macroscopic evaluation of the stent indicated no significant change at 1 month (n = 3) or fragmentation with discoloration at 3 months (n = 5). On microscopic examination of CBD specimens, the tissue inflammation score was significantly higher in the stent group than in the control group (mean ± standard deviation (SD), 5.63 ± 2.07 vs. 2.00 ± 1.73; P = 0.039) and thickness of fibrosis of the CBD wall was significantly higher than that of the control group (0.46 ± 0.12 mm vs. 0.21 ± 0.05 mm; P = 0.012). Despite mild bile duct inflammation and fibrosis, 3D-printed biodegradable biliary stents showed good feasibility and safety in porcine bile ducts, suggesting their potential for use in the prevention of postoperative biliary strictures.

Phantom Study on the Robustness of MR Radiomics Features: Comparing the Applicability of 3D Printed and Biological Phantoms

The objectives of our study were to (a) evaluate the feasibility of using 3D printed phantoms in magnetic resonance imaging (MR) in assessing the robustness and repeatability of radiomic parameters and (b) to compare the results obtained from the 3D printed phantoms to metrics obtained in biological phantoms. To this end, three different 3D phantoms were printed: a Hilbert cube (5 × 5 × 5 cm³) and two cubic quick response (QR) code phantoms (a large phantom (large QR) (5 × 5 × 4 cm³) and a small phantom (small QR) (4 × 4 × 3 cm³)). All 3D printed and biological phantoms (kiwis, tomatoes, and onions) were scanned thrice on clinical 1.5 T and 3 T MR with 1 mm and 2 mm isotropic resolution. Subsequent analyses included analyses of several radiomics indices (RI), their repeatability and reliability were calculated using the coefficient of variation (CV), the relative percentage difference (RPD), and the interclass coefficient (ICC) parameters. Additionally, the readability of QR codes obtained from the MR images was examined with several mobile phones and algorithms. The best repeatability (CV ≤ 10%) is reported for the acquisition protocols with the highest spatial resolution. In general, the repeatability and reliability of RI were better in data obtained at 1.5 T (CV = 1.9) than at 3 T (CV = 2.11). Furthermore, we report good agreements between results obtained for the 3D phantoms and biological phantoms. Finally, analyses of the read-out rate of the QR code revealed better texture analyses for images with a spatial resolution of 1 mm than 2 mm. In conclusion, 3D printing techniques offer a unique solution to create textures for analyzing the reliability of radiomic data from MR scans.

Nanomaterial integrated 3D printing for biomedical applications

3D printing technology, otherwise known as additive manufacturing, has provided a promising tool for manufacturing customized biomaterials for tissue engineering and regenerative medicine applications. A vast variety of biomaterials including metals, ceramics, polymers, and composites are currently being used as base materials in 3D printing. In recent years, nanomaterials have been incorporated into 3D printing polymers to fabricate innovative, versatile, multifunctional hybrid materials that can be used in many different applications within the biomedical field. This review focuses on recent advances in novel hybrid biomaterials composed of nanomaterials and 3D printing technologies for biomedical applications. Various nanomaterials including metal-based nanomaterials, metal-organic frameworks, upconversion nanoparticles, and lipid-based nanoparticles used for 3D printing are presented, with a summary of the mechanisms, functional properties, advantages, disadvantages, and applications in biomedical 3D printing. To finish, this review offers a perspective and discusses the challenges facing the further development of nanomaterials in biomedical 3D printing.

Three-Dimensional Bioprinting for Cartilage Tissue Engineering: Insights into Naturally-Derived Bioinks from Land and Marine Sources

In regenerative medicine and tissue engineering, the possibility to: (I) customize the shape and size of scaffolds, (II) develop highly mimicked tissues with a precise digital control, (III) manufacture complex structures and (IV) reduce the wastes related to the production process, are the main advantages of additive manufacturing technologies such as three-dimensional (3D) bioprinting. Specifically, this technique, which uses suitable hydrogel-based bioinks, enriched with cells and/or growth factors, has received significant consideration, especially in cartilage tissue engineering (CTE). In this field of interest, it may allow mimicking the complex native zonal hyaline cartilage organization by further enhancing its biological cues. However, there are still some limitations that need to be overcome before 3D bioprinting may be globally used for scaffolds’ development and their clinical translation. One of them is represented by the poor availability of appropriate, biocompatible and eco-friendly biomaterials, which should present a series of specific requirements to be used and transformed into a proper bioink for CTE. In this scenario, considering that, nowadays, the environmental decline is of the highest concerns worldwide, exploring naturally-derived hydrogels has attracted outstanding attention throughout the scientific community. For this reason, a comprehensive review of the naturally-derived hydrogels, commonly employed as bioinks in CTE, was carried out. In particular, the current state of art regarding eco-friendly and natural bioinks’ development for CTE was explored. Overall, this paper gives an overview of 3D bioprinting for CTE to guide future research towards the development of more reliable, customized, eco-friendly and innovative strategies for CTE.

3D printing in Ophthalmology: From medical implants to personalised medicine

3D printing was invented thirty years ago. However, its application in healthcare became prominent only in recent years to provide solutions for drug delivery and clinical challenges, and is constantly evolving. This cost-efficient technique utilises biocompatible materials and is used to develop model implants to provide a greater understanding of human anatomy and diseases, and can be used for organ transplants, surgical planning and for the manufacturing of advanced drug delivery systems. In addition, 3D printed medical devices and implants can be customised for each patient to provide a more tailored treatment approach. The advantages and applications of 3D printing can be used to treat patients with different eye conditions, with advances in 3D bioprinting offering novel therapy applications in ophthalmology. The purpose of this review paper is to provide an in-depth understanding of the applications and advantages of 3D printing in treating different ocular conditions in the cornea, glaucoma, retina, lids and orbits.

Development of 3-dimensional printed simulation surgical training models for endoscopic endonasal and transorbital surgery

Background

Endoscopic skull base surgery (ESBS) is complex, requiring methodical and unremitting surgical training. Herein, we describe the development and evaluation of a novel three-dimensional (3D) printed simulation model for ESBS. We further validate the efficacy of this model as educational support in neurosurgical training.

Methods

A patient-specific 3D printed simulation model using living human imaging data was established and evaluated in a task-based hands-on dissection program. Endoscopic endonasal and transorbital procedures were simulated on the model by neurosurgeons and otorhinolaryngology surgeons of varying experience. All procedures were recorded using a high-definition camera coupled with digital video recorder system. The participants were asked to complete a post-procedure questionnaire to validate the efficacy of the model.

Results

Fourteen experts and 22 trainees participated in simulations, and the 32 participants completed the post-procedure survey. The anatomical realism was scored as 4.0/5.0. The participants rated the model as helpful in hand-eye coordination training (4.7/5.0) and improving surgical skills (4.6/5.0) for ESBS. All participants believed that the model was useful as educational support for trainees (4.7 [ ± 0.5]). However, the color (3.6/5.0) and soft tissue feedback parameters (2.8/5) scored low.

Conclusion

This study shows that high-resolution 3D printed skull base models for ESBS can be generated with high anatomical accuracy and acceptable haptic feedback. The simulation program of ESBS using this model may be supplemental or provide an alternative training platform to cadaveric dissection.

3D printing methods for radiological anthropomorphic phantoms

Three dimensional (3D) printing technology has been widely evaluated for the fabrication of various anthropomorphic phantoms during the last couple of decades. The demand for such high quality phantoms is constantly rising and gaining an ever-increasing interest. Although, in a short time 3D printing technology provided phantoms with more realistic features when compared to the previous conventional methods, there are still several aspects to be explored. One of these aspects is the further development of the current 3D printing methods and software devoted to radiological applications. The current 3D printing software and methods usually employ 3D models, while the direct association of medical images with the 3D printing process is needed in order to provide results of higher accuracy and closer to the actual tissues' texture. Another aspect of high importance is the development of suitable printing materials. Ideally, those materials should be able to emulate the entire range of soft and bone tissues, while still matching the human's anatomy. Five types of 3D printing methods have been mainly investigated so far: (a) solidification of photo-curing materials; (b) deposition of melted plastic materials; (c) printing paper-based phantoms with radiopaque ink; (d) melting or binding plastic powder; and (e) bio-printing. From the first and second category, polymer jetting technology and fused filament fabrication (FFF), also known as fused deposition modelling (FDM), are the most promising technologies for the fulfilment of the requirements of realistic and radiologically equivalent anthropomorphic phantoms. Another interesting approach is the fabrication of radiopaque paper-based phantoms using inkjet printers. Although, this may provide phantoms of high accuracy, the utilized materials during the fabrication process are restricted to inks doped with various contrast materials. A similar condition applies to the polymer jetting technology, which despite being quite fast and very accurate, the utilized materials are restricted to those capable of polymerization. The situation is better for FFF/FDM 3D printers, since various compositions of plastic filaments with external substances can be produced conveniently. Although, the speed and accuracy of this 3D printing method are lower compared to the others, the relatively low-cost, constantly improving resolution, sufficient printing volume and plethora of materials are quite promising for the creation of human size heterogeneous phantoms and their adaptation to the treatment procedures of patients in the current health systems.

Low-Cost Cranioplasty—A Systematic Review of 3D Printing in Medicine

The high cost of biofabricated titanium mesh plates can make them out of reach for hospitals in low-income countries. To increase the availability of cranioplasty, the authors of this work investigated the production of polymer-based endoprostheses. Recently, cheap, popular desktop 3D printers have generated sufficient opportunities to provide patients with on-demand and on-site help. This study also examines the technologies of 3D printing, including SLM, SLS, FFF, DLP, and SLA. The authors focused their interest on the materials in fabrication, which include PLA, ABS, PET-G, PEEK, and PMMA. Three-dimensional printed prostheses are modeled using widely available CAD software with the help of patient-specific DICOM files. Even though the topic is insufficiently researched, it can be perceived as a relatively safe procedure with a minimal complication rate. There have also been some initial studies on the costs and legal regulations. Early case studies provide information on dozens of patients living with self-made prostheses and who are experiencing significant improvements in their quality of life. Budget 3D-printed endoprostheses are reliable and are reported to be significantly cheaper than the popular counterparts manufactured from polypropylene polyester.

Design and Mechanical Characterization Using Digital Image Correlation of Soft Tissue-Mimicking Polymers

Present and future anatomical models for biomedical applications will need bio-mimicking three-dimensional (3D)-printed tissues. These would enable, for example, the evaluation of the quality-performance of novel devices at an intermediate step between ex-vivo and in-vivo trials. Nowadays, PolyJet technology produces anatomical models with varying levels of realism and fidelity to replicate organic tissues. These include anatomical presets set with combinations of multiple materials, transitions, and colors that vary in hardness, flexibility, and density. This study aims to mechanically characterize multi-material specimens designed and fabricated to mimic various bio-inspired hierarchical structures targeted to mimic tendons and ligaments. A Stratasys^® J750™ 3D Printer was used, combining the Agilus30™ material at different hardness levels in the bio-mimicking configurations. Then, the mechanical properties of these different options were tested to evaluate their behavior under uni-axial tensile tests. Digital Image Correlation (DIC) was used to accurately quantify the specimens’ large strains in a non-contact fashion. A difference in the mechanical properties according to pattern type, proposed hardness combinations, and matrix-to-fiber ratio were evidenced. The specimens V, J1, A1, and C were selected as the best for every type of pattern. Specimens V were chosen as the leading combination since they exhibited the best balance of mechanical properties with the higher values of Modulus of elasticity (2.21 ± 0.17 MPa), maximum strain (1.86 ± 0.05 mm/mm), and tensile strength at break (2.11 ± 0.13 MPa). The approach demonstrates the versatility of PolyJet technology that enables core materials to be tailored based on specific needs. These findings will allow the development of more accurate and realistic computational and 3D printed soft tissue anatomical solutions mimicking something much closer to real tissues.

Overcoming challenges to develop technology for child health

Millions of children and young people (CYP) in the UK are affected by chronic or rare health conditions. Rapid advances in science and technology have resulted in CYP with chronic and rare conditions now surviving well into adulthood. New technologies have the potential to improve short- and long-term health outcomes for CYP with health conditions, prevent adult onset disease and complications, and reduce the burden on health services. There is thus a need for targeted investment and appropriate governance in child health technology development to address the specific needs of this population; health technology must be versatile to meet the social, anatomical, cognitive, psychological, and physiological changes inherent to childhood development. Despite the growing demand for health technology for a sizeable global population, industry still wrongly perceives the market size is relatively small, and health technology development is often localised and fragmented with limited scope for spread and adoption. These challenges can be overcome by validating and prioritising unmet needs, involving CYP and their families throughout the innovation pathway, facilitating effective partnerships with key stakeholders, and utilising national and international infrastructure and networks. This paper outlines five innovations supported by NIHR Children and Young People MedTech Co-operative that illustrate how common challenges in child health technology development can be overcome. It is essential that we continue to address such challenges and invest in the health and wellbeing of CYP.

Sistematização das etapas para impressão de modelos 3D de deformidades ortopédicas

Assim como em diversas áreas do conhecimento, a tecnologia de prototipagem rápida ou manufatura aditiva, conhecida popularmente como impressão tridimensional (3D), vem ganhando espaço na medicina nos últimos anos, com diferentes aplicações. Inúmeros são os benefícios desta ciência na cirurgia ortopédica, ao permitir a conversão de exames de imagem em modelos tridimensionais. Diante disso, o objetivo do presente estudo é descrever um passo-a-passo prático para a impressão de peças a partir de exames de imagem de pacientes. Trata-se de um estudo metodológico, considerando exames de tomografia computadorizada (TC) pré-operatórios de pacientes portadores de deformidades ortopédicas. Inicialmente, o exame em formato digital imaging and communications in medicine (DICOM, na sigla em inglês) deve ser importado para o software de reconstrução tridimensional de estruturas anatômicas para o processo de segmentação e de conversão para o formato stereolithography (STL, na sigla em inglês). A próxima etapa é a importação do arquivo STL para o software de modelagem 3D, o qual permite trabalhar de forma livre manipulando a malha 3D. Finalizado o processo de edição, deve-se transferir o arquivo para o software fatiador para realizar as configurações de impressão e para salvar o arquivo em formato G-code para a materialização do objeto na impressora. Os modelos 3D foram impressos de forma aditiva, na impressora de tecnologia fused deposition modeling (FDM, na sigla em inglês) GTMax3D Core A3v2.

Application of 3D printing in assessment and demonstration of stab injuries

In stabbing related fatalities, the forensic pathologist has to assess the direction of wound track (thus, the direction of the stabbing) and the weapon’s possible characteristics by examining the stab wound. The determination of these characteristics can be made only with a high level of uncertainty, and the precise direction of the stabbing is often difficult to assess if only soft tissues are injured. Previously reported techniques used for the assessment of these wound characteristics have substantial limitations. This manuscript presents a method using today’s easily accessible three-dimensional (3D) printing technology for blade-wound comparison and wound track determination. Scanning and 3D printing of knives is a useful method to identify weapons and determine the precise stabbing direction in a stabbing incident without compromising the trace evidence or the autopsy results. Ballistic gel experiment, and dynamic stabbing test experiments prove the method can be applied in safety, without compromising the autopsy results. Identification of the exact knife is not possible with complete certainty but excluding certain knives will decrease the number of necessary DNA examinations, hence it can lower the burden on forensic genetic laboratories. The method addresses many of the shortcomings of previously used methods of probe insertion or post-mortem CT. Insertion of the printed knife into the wound gives a good visual demonstration of the stabbing direction, thus easing the forensic reconstruction of the stabbing incident. After combining the 3D printing with photogrammetry, the achieved 3D visualization is useful for courtroom demonstration and educational purposes.

Analysis of different geometrical features to achieve close-to-bone stiffness material properties in medical device: A feasibility numerical study

BACKGROUND AND OBJECTIVE

In orthopedic medical devices, elasto-plastic behavior differences between bone and metallic materials could lead to mechanical issues at the bone-implant interface, as stress shielding. Those issue are mainly related to knee and hip arthroplasty, and they could be responsible for implant failure. To reduce mismatching-related adverse events between bone and prosthesis mechanical properties, modifying the implant's internal geometry varying the bulk stiffness and density could be the right approach. Therefore, this feasibility study aims to assess which in-body gap geometry improves, by reducing, the bulk stiffness.

METHODS

Using five finite element models, a uniaxial compression test in five cubes with a 20 mm thickness was simulated and analyzed. The displacements, strain and Young Modulus were calculated in four cubes, each containing internal prismatic gaps with different transversal sections (squared, hexagonal, octagonal, and circular). Those were compared with a fifth full-volume cube used as control.

RESULTS

The most significant difference have been achieved in displacement values, in cubes containing internal gaps with hexagonal and circular transversal sections (82 µm and 82.5 µm, respectively), when compared to the full-volume cube (69.3 µm).

CONCLUSIONS

This study suggests that hexagonal and circular shape of the gaps allows obtaining the lower rigidity in a size range of 4 mm, offering a starting approach to achieve a "close-to-bone" material, with a potential use in prosthetic devices with limited thickness.

Design Aspects of Additive Manufacturing at Microscale: A Review

Additive manufacturing (AM) technology has been researched and developed for almost three decades. Microscale AM is one of the fastest-growing fields of research within the AM area. Considerable progress has been made in the development and commercialization of new and innovative microscale AM processes, as well as several practical applications in a variety of fields. However, there are still significant challenges that exist in terms of design, available materials, processes, and the ability to fabricate true three-dimensional structures and systems at a microscale. For instance, microscale AM fabrication technologies are associated with certain limitations and constraints due to the scale aspect, which may require the establishment and use of specialized design methodologies in order to overcome them. The aim of this paper is to review the main processes, materials, and applications of the current microscale AM technology, to present future research needs for this technology, and to discuss the need for the introduction of a design methodology. Thus, one of the primary concerns of the current paper is to present the design aspects describing the comparative advantages and AM limitations at the microscale, as well as the selection of processes and materials.

Multi-Functional 3D-Printed Vat Photopolymerization Biomedical-Grade Resin Reinforced with Binary Nano Inclusions: The Effect of Cellulose Nanofibers and Antimicrobial Nanoparticle Agents

This study introduced binary nanoparticle (NP) inclusions into a biomedical-grade photosensitive resin (Biomed Clear-BC). Multi-functional, three-dimensional (3D) printed objects were manufactured via the vat photopolymerization additive manufacturing (AM) technique. Cellulose nanofibers (CNFs) as one dimensional (1D) nanomaterial have been utilized for the mechanical reinforcement of the resin, while three different spherical NPs, namely copper NPs (nCu), copper oxide NPs (nCuO), and a commercial antimicrobial powder (nAP), endowed the antimicrobial character. The nanoparticle loading was kept constant at 1.0 wt.% to elucidate any synergistic effects as a function of the filler loading. Raman, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) revealed the chemical/spectroscopic and thermal properties of the different manufactured samples. Scanning electron microscopy and Atomic Force Microscopy (AFM) revealed the morphology of the samples. Mechanical properties revealed the reinforcement mechanisms, namely that BC/CNF (1.0 wt.%) exhibited a 102% and 154% enhancement in strength and modulus, respectively, while BC/CNF(1.0 wt.%)/AP(1.0 wt.%) exhibited a 95% and 101% enhancement, as well as an antibacterial property, which was studied using a screening agar well diffusion method. This study opens the route towards novel, multi-functional materials for vat photopolymerization 3D printing biomedical applications, where mechanical reinforcement and antibacterial performance are typically required in the operational environment.

Fused Filament Fabrication 3D Printing: Quantification of Exposure to Airborne Particles

Fused Filament Fabrication (FFF) has been established as a widely practiced Additive Manufacturing technique, using various thermoplastic filaments. Carbon fibre (CF) additives enhance mechanical properties of the materials. The main operational hazard of the FFF technique explored in the literature is the emission of Ultrafine Particles and Volatile Organic Compounds. Exposure data regarding novel materials and larger scale operations is, however, still lacking. In this work, a thorough exposure assessment measurement campaign is presented for a workplace applying FFF 3D printing in various setups (four different commercial devices, including a modified commercial printer) and applying various materials (polylactic acid, thermoplastic polyurethane, copolyamide, polyethylene terephthalate glycol) and CF-reinforced thermoplastics (thermoplastic polyurethane, polylactic acid, polyamide). Portable exposure assessment instruments are employed, based on an established methodology, to study the airborne particle exposure potential of each process setup. The results revealed a distinct exposure profile for each process, necessitating a different safety approach per setup. Crucially, high potential for exposure is detected in processes with two printers working simultaneously. An updated engineering control scheme is applied to control exposures for the modified commercial printer. The establishment of a flexible safety system is vital for workplaces that apply FFF 3D printing.

Effectiveness and Applications of a Metal-Coated HNT/Polylactic Acid Antimicrobial Filtration System

A broad-spectrum antimicrobial respiration apparatus designed to fight bacteria, viruses, fungi, and other biological agents is critical in halting the current pandemic’s trajectory and containing future outbreaks. We applied a simple and effective electrodeposition method for metal (copper, silver, and zinc) coating the surface of halloysite nanotubes (HNTs). These nanoparticles are known to possess potent antiviral and antimicrobial properties. Metal-coated HNTs (mHNTs) were then added to polylactic acid (PLA) and extruded to form an mHNT/PLA 3D composite printer filament. Our composite 3D printer filament was then used to fabricate an N95-style mask with an interchangeable/replaceable filter with surfaces designed to inactivate a virus and kill bacteria on contact, thus reducing deadly infections. The filter, made of a multilayered antimicrobial/mHNT blow spun polymer and fabric, is disposable, while the mask can be sanitized and reused. We used several in vitro means of assessing critical clinical features and assessed the bacterial growth inhibition against commonly encountered bacterial strains. These tests demonstrated the capability of our antimicrobial filament to fabricate N95 masks and filters that possessed antibacterial capabilities against both Gram-negative and Gram-positive bacteria.

Association between 3D Printing-Assisted Pelvic or Acetabular Fracture Surgery and the Length of Hospital Stay in Nongeriatric Male Adults

Pelvic and acetabular fractures are challenging for orthopedic surgeons, but 3D printing has many benefits in treating these fractures and has been applied worldwide. This study aimed to determine whether 3D printing can shorten the length of hospital stay (LHS) in nongeriatric male adult patients with these fractures. This is a single-center retrospective study of 167 nongeriatric male adult participants from August 2009 to December 2021. Participants were divided into two groups based on whether they received 3D printing assistance. Subgroup analyses were performed. Pearson’s correlation and multivariable linear regression models were used to analyze the LHS and the parameters. Results showed that 3D printing-assisted surgery did not affect LHS in the analyzed patients. The LHS was positively correlated with the Injury Severity Score (ISS). Initial hemoglobin levels were negatively associated with LHS in patients aged 18−40 and non-major trauma (ISS < 16) patients. In 40−60-year-old and non-major trauma patients, the duration from fracture to admission was significantly associated with LHS. This study indicates that 3D-assisted technology for pelvic or acetabular fracture surgery for nongeriatric male adults does not influence the LHS. More importantly, the initial evaluation of patients in the hospital was the main predictor of the LHS.

Cinematic rendering of paediatric musculoskeletal pathologies: initial experiences with CT

Cinematic rendering (CR) is a novel post-processing technique similar to volume rendering (VR), which allows for a more photorealistic imaging reconstruction by using a complex light modelling algorithm, incorporating information from multiple light paths and predicted photon scattering patterns. Several recent publications relating to adult imaging have argued that CR gives a better "realism" and "expressiveness" experience over VR techniques. CR has also been shown to improve visualisation of musculoskeletal and vascular anatomy compared with conventional CT viewing, and may help non-radiologists to understand complex patient anatomy. In this review, we provide an overview of how CR could be used in paediatric musculoskeletal imaging, particularly in complex diagnoses, surgical planning, and patient consent processes. We present a direct comparison of VR and CR reconstructions across a range of congenital and acquired musculoskeletal pathologies, highlighting potential advantages and areas for further research.

Multidisciplinary Simulation Improves Resident Confidence for Pregnant Patients Requiring Surgical Intervention

Introduction: Hepatocellular adenomas are a rare but serious cause of bleeding, which is further complicated by pregnancy. Interprofessional cooperation is a key component of residency education, thus simulations designed to integrate multiple programs are mutually beneficial. This simulation details surgical and obstetric management of a pregnant patient in hemorrhagic shock from a bleeding hepatocellular adenoma. Objectives for the study were to evaluate learners’ confidence to 1) prioritize the care of a pregnant patient with hemoperitoneum and hemorrhagic shock, 2) demonstrate interdisciplinary collaboration with other specialties, 3) apply massive transfusion protocol (MTP) in the appropriate clinical setting, and 4) analyze critical decisions for evaluating pregnant females with severe abdominal pain.

Methods: Obstetric, general surgery, and anesthesia residents, along with labor and delivery nurses participated in a simulated clinical scenario that focused on the management of a pregnant patient in hemorrhagic shock. The learners evaluated the educational session using a standard Return on Investment in Learning survey immediately following the session.

Results: A total of 23 residents and medical students gave feedback on the experience. The main learning objectives were met with increased confidence in the four learning objectives by 77.3-95.4% of responders. Overall, greater than 90% of participants felt the simulation was relevant to their training and realistic, with 100% responding that the course provided new, or clarified existing information for them.

Conclusion: A multidisciplinary simulation-based educational intervention was successful in improving learner confidence in managing a complicated surgical emergency in a pregnant patient with inter-residency cooperation.

Vital Role of In-House 3D Lab to Create Unprecedented Solutions for Challenges in Spinal Surgery, Practical Guidelines and Clinical Case Series

For decades, the advantages of rapid prototyping for clinical use have been recognized. However, demonstrations of potential solutions to treat spinal problems that cannot be solved otherwise are scarce. In this paper, we describe the development, regulatory process, and clinical application of two types of patient specific 3D-printed devices that were developed at an in-house 3D point-of-care facility. This 3D lab made it possible to elegantly treat patients with spinal problems that could not have been treated in a conventional manner. The first device, applied in three patients, is a printed nylon drill guide, with such accuracy that it can be used for insertion of cervical pedicle screws in very young children, which has been applied even in semi-acute settings. The other is a 3D-printed titanium spinal column prosthesis that was used to treat progressive and severe deformities due to lysis of the anterior column in three patients. The unique opportunity to control size, shape, and material characteristics allowed a relatively easy solution for these patients, who were developing paraplegia. In this paper, we discuss the pathway toward the design and final application, including technical file creation for dossier building and challenges within a point-of-care lab.

3D Printing Technologies in Biosensors Production: Recent Developments

Recent advances in 3D printing technologies and materials have enabled rapid development of innovative sensors for applications in different aspects of human life. Various 3D printing technologies have been adopted to fabricate biosensors or some of their components thanks to the advantages of these methodologies over the traditional ones, such as end-user customization and rapid prototyping. In this review, the works published in the last two years on 3D-printed biosensors are considered and grouped on the basis of the 3D printing technologies applied in different fields of application, highlighting the main analytical parameters. In the first part, 3D methods are discussed, after which the principal achievements and promising aspects obtained with the 3D-printed sensors are reported. An overview of the recent developments on this current topic is provided, as established by the considered works in this multidisciplinary field. Finally, future challenges on the improvement and innovation of the 3D printing technologies utilized for biosensors production are discussed.

Improving Nasopharyngeal Swab Technique via Simulation for Frontline Workers

OBJECTIVES/HYPOTHESIS

Nasopharyngeal swabs currently remain the gold standard for COVID-19 sample collection. A surge in testing volume has resulted in a large number of health care workers who are unfamiliar with nasal anatomy performing this test, which can lead to improper collection practices culminating in false-negative results and complications. Therefore, we aimed to assess the accuracy and educational potential of a realistic 3D-printed nasal swab simulator to expedite health care workers' skill acquisition.

STUDY DESIGN

Prospective pre-post interventional study.

METHODS

A nasal swab task trainer (NSTT) was developed to scale from computed tomography data with a deviated septum. Frontline workers at COVID-19 testing sites in Ontario, Canada, were recruited to use the NSTT for nasopharyngeal swab training. Integrated video recording capability allowed participants to self-evaluate procedure accuracy. A five-point Likert scale was collected regarding the NSTT's educational value and procedural fidelity.

RESULTS

Sixty-two frontline workers included in the study were primarily registered nurses (52%) or paramedics (16%). Following simulator use, self-assessed accuracy improved in 77% of all participants and 100% of participants who expressed low confidence before training. Ninety-four percent reported that the NSTT provided a complete educational experience, and 82% regarded the system as a more effective training approach than what is currently available. Eighty-one indicated that the simulator should be used at all COVID-19 testing sites, with 77% stating province-wide implementation was warranted.

CONCLUSIONS

The nasal swab task trainer is an effective educational tool that appears well-suited for improved skill acquisition in COVID-19 testing and may be useful for training other nasal swab applications.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:38-42, 2023.

Three-dimensional printing in paediatric orthopaedic surgery

Three-dimensional (3D) printing is a rapidly evolving and promising field to improve outcomes of orthopaedic surgery. The use of patient-specific 3D-printed models is specifically interesting in paediatric orthopaedic surgery, as limb deformity corrections often require an individual 3D treatment. In this editorial, various operative applications of 3D printing in paediatric orthopaedic surgery are discussed. The technical aspects and the imaging acquisition with computed tomography and magnetic resonance imaging are outlined. Next, there is a focus on the intraoperative applications of 3D printing during paediatric orthopaedic surgical procedures. An overview of various upper and lower limb deformities in paediatrics is given, in which 3D printing is already implemented, including post-traumatic forearm corrections and proximal femoral osteotomies. The use of patient-specific instrumentation (PSI) or guiding templates during the surgical procedure shows to be promising in reducing operation time, intraoperative haemorrhage and radiation exposure. Moreover, 3D-printed models for the use of PSI or patient-specific navigation templates are promising in improving the accuracy of complex limb deformity surgery in children. Lastly, the future of 3D printing in paediatric orthopaedics extends beyond the intraoperative applications; various other medical applications include 3D casting and prosthetic limb replacement. In conclusion, 3D printing opportunities are numerous, and the fast developments are exciting, but more evidence is required to prove its superiority over conventional paediatric orthopaedic surgery.

Development of 3D-Printed, Liquisolid and Directly Compressed Glimepiride Tablets, Loaded with Black Seed Oil Self-Nanoemulsifying Drug Delivery System: In Vitro and In Vivo Characterization

Glimepiride is characterized by an inconsistent dissolution and absorption profile due to its limited aqueous solubility. The aim of this study was to develop glimepiride tablets using three different manufacturing techniques, as well as to study their quality attributes and pharmacokinetics behavior. Black seed oil based self-nanoemulsifying drug delivery system (SNEDDS) formulation was developed and characterized. Glimepiride liquisolid and directly compressed tablets were prepared and their pre-compression and post-compression characteristics were evaluated. Semi-solid pastes loaded with SNEDDS were prepared and used to develop three-dimensional printing tablets utilizing the extrusion technique. In vivo comparative pharmacokinetics study was conducted on Male Wistar rats using a single dose one-period parallel design. The developed SNEDDS formulation showed a particle size of 45.607 ± 4.404 nm, and a glimepiride solubility of 25.002 ± 0.273 mg/mL. All the studied tablet formulations showed acceptable pre-compression and post-compression characteristics and a difference in their in vitro drug release behavior. The surface of the liquisolid and directly compressed tablets was smooth and non-porous, while the three-dimensional printing tablets showed a few porous surfaces. The inner structure of the liquisolid tablets showed some cracks and voids between the incorporated tablet ingredients while that of the three-dimensional printing tablets displayed some tortuosity and a gel porous-like structure. Most of the computed pharmacokinetic parameters improved with the liquisolid and three-dimensional printed tablets. The relative bioavailabilities of the three-dimensional printed and liquisolid tablets compared to commercial product were 121.68% and 113.86%, respectively. Therefore, the liquisolid and three-dimensional printed tablets are promising techniques for modifying glimepiride release and improving in vivo performance but more clinical investigations are required.

An Improved SAC-IA Algorithm Based on Voxel Nearest Neighbor Search

To construct a three-dimensional (3D) model of a tooth, multiple charge coupled device (CCD) cameras should be deployed in practice. Each CCD camera captures part of the tooth from a different angle. The images captured by different cameras must be registered to construct the relational 3D model. Sample consensus initial alignment (SAC-IA) algorithm is usually adopted, and fast point feature histograms (FPFH) descriptor is selected to calculate eigenvalues for different images. However, the original SAC-IA algorithm cannot satisfy a real-time application because of low efficiency and accuracy. According to the application of voxel nearest neighbor search in octree in 3D data search, this paper proposes an improved SAC-IA algorithm based on voxel nearest neighbor search to improve the efficiency and accuracy of the algorithm. The experimental results show that comparing to the traditional SAC-IA algorithm, the proposed algorithm based on voxel nearest neighbor search improves the efficiency by 20.95% and the registration accuracy by 24.95%. The improved algorithm can be deployed to construct a 3D model of a tooth as well as 3D model construction of other objects based on coded structured light.

How 3D Printing Is Reshaping Translational Research

"Translational Research" has traditionally been defined as taking basic scientific findings and developing new diagnostic tools, drugs, devices and treatment options for patients, that are translated into practice, reach the people and populations for whom they are intended and are implemented correctly. The implication is of a unidirectional flow from "the bench to bedside". The rapidly emergent field of additive manufacturing (3D printing) is contributing to a major shift in translational medical research. This includes the concept of bidirectional or reverse translation, early collaboration between clinicians, bio-engineers and basic scientists, and an increasingly entrepreneurial mindset. This coincides with, and is strongly complemented by, the rise of systems biology. The rapid pace at which this type of translational research can occur brings a variety of potential pitfalls and ethical concerns. Regulation surrounding implantable medical devices is struggling to keep up. 3D printing has opened the way for personalization which can make clinical outcomes hard to assess and risks putting the individual before the community. In some instances, novelty and hype has led to loss of transparency of outcomes with dire consequence. Collaboration with commercial partners has potential for conflict of interest. Nevertheless, 3D printing has dramatically changed the landscape of translational research. With early recognition and management of the potential risks, the benefits of reshaping the approach to translational research are enormous. This impact will extend into many other areas of biomedical research, re-establishing that science is more than a body of research. It is a way of thinking.

Medical Device Development for Children and Young People-Reviewing the Challenges and Opportunities

Development of specific medical devices (MDs) is required to meet the healthcare needs of children and young people (CYP). In this context, MD development should address changes in growth and psychosocial maturation, physiology, and pathophysiology, and avoid inappropriate repurposing of adult technologies. Underpinning the development of MD for CYP is the need to ensure MD safety and effectiveness through pediatric MD-specific regulations. Contrary to current perceptions of limited market potential, the global pediatric healthcare market is expected to generate around USD 15,984 million by 2025. There are 1.8 billion young people in the world today; 40% of the global population is under 24, creating significant future healthcare market opportunities. This review highlights a number of technology areas that have led to successful pediatric MD, including 3D printing, advanced materials, drug delivery, and diagnostic imaging. To ensure the targeted development of MD for CYP, collaboration across multiple professional disciplines is required, facilitated by a platform to foster collaboration and drive innovation. The European Pediatric Translational Research Infrastructure (EPTRI) will be established as the European platform to support collaboration, including the life sciences industrial sector, to identify unmet needs in child health and support the development, adoption, and commercialization of pediatric MDs.

Three-Dimensional-Printed Scaffolds for Meniscus Tissue Engineering: Opportunity for the Future in the Orthopaedic World

The meniscus is a critical component of a healthy knee joint. It is a complex and vital fibrocartilaginous tissue that maintains appropriate biomechanics. Injuries of the meniscus, particularly in the inner region, rarely heal and usually progress into structural breakdown, followed by meniscus deterioration and initiation of osteoarthritis. Conventional therapies range from conservative treatment, to partial meniscectomy and even meniscus transplantation. All the above have high long-term failure rates, with recurrence of symptoms. This communication presents a brief account of in vitro and in vivo studies and describes recent developments in the field of 3D-printed scaffolds for meniscus tissue engineering. Current research in meniscal tissue engineering tries to combine polymeric biomaterials, cell-based therapy, growth factors, and 3D-printed scaffolds to promote the healing of meniscal defects. Today, 3D-printing technology represents a big opportunity in the orthopaedic world to create more specific implants, enabling the rapid production of meniscal scaffolds and changing the way that orthopaedic surgeons plan procedures. In the future, 3D-printed meniscal scaffolds are likely to be available and will also be suitable substitutes in clinical applications, in an attempt to imitate the complexity of the native meniscus.

Surface Treatment and Bioinspired Coating for 3D-Printed Implants

Three-dimensional (3D) printing technology has developed rapidly and demonstrates great potential in biomedical applications. Although 3D printing techniques have good control over the macrostructure of metallic implants, the surface properties have superior control over the tissue response. By focusing on the types of surface treatments, the osseointegration activity of the bone-implant interface is enhanced. Therefore, this review paper aims to discuss the surface functionalities of metallic implants regarding their physical structure, chemical composition, and biological reaction through surface treatment and bioactive coating. The perspective on the current challenges and future directions for development of surface treatment on 3D-printed implants is also presented.

Additive manufacturing technology of polymeric materials for customized products: recent developments and future prospective

The worldwide demand for additive manufacturing (AM) is increasing due to its ability to produce more challenging customized objects based on the process parameters for engineering applications. The processing of conventional materials by AM processes is a critically demanded research stream, which has generated a path-breaking scenario in the rapid manufacturing and upcycling of plastics. The exponential growth of AM in the worldwide polymer market is expected to exceed 20 billion US dollars by 2021 in areas of automotive, medical, aerospace, energy and customized consumer products. The development of functional polymers and composites by 3D printing-based technologies has been explored significantly due to its cost-effective, easier integration into customized geometries, higher efficacy, higher precision, freedom of material utilization as compared to traditional injection molding, and thermoforming techniques. Since polymers are the most explored class of materials in AM to overcome the limitations, this review describes the latest research conducted on petroleum-based polymers and their composites using various AM techniques such as fused filament fabrication (FFF), selective laser sintering (SLS), and stereolithography (SLA) related to 3D printing in engineering applications such as biomedical, automotive, aerospace and electronics.

Preparation, properties and application of graphene-based materials in tissue engineering scaffolds

Tissue engineering has great application prospect as an effective treatment for tissue and organ injury, functional reduction or loss. Bioactive tissues are reconstructed and damaged organs are repaired by the three elements including cells, scaffold materials and growth factors. Graphene-based composites can be used as reinforcing auxiliary materials for tissue scaffold preparation because of their large specific surface area, and good mechanical support. Tissue engineering scaffolds with graphene-based composites have been widely studied. Part of research have focused on the application of graphene-based composites in single tissue engineering; The basic principles of graphene materials used in tissue engineering are summarized in some researches. Some studies emphasized the key problems and solutions urgently needed to be solved in the development of tissue engineering, and discussed their application prospect. Some related studies mainly focused on the conductivity of graphene, and discussed the application of electroactive scaffolds in tissue engineering. In this review, the composite materials for preparing tissue engineering scaffolds are briefly described, which emphasizes the preparation methods, biological properties and practical applications of graphene-based composite scaffolds. The synthetic techniques with stressing solvent casting, electrospinning and 3D printing are introduced in detail. The mechanical, cell-oriented and biocompatible properties of graphene-based composite scaffolds in tissue engineering are analyzed and summarized. Their applications in bone tissue engineering, nerve tissue engineering, cardiovascular tissue engineering and other tissue engineering are summarized systematically. In addition, this work also looks forward to the difficulties and challenges in the future research, providing some references for the follow-up research of graphene-based composites in tissue engineering scaffolds.

An Overview of Natural Polymers as Reinforcing Agents for 3D Printing

Three-dimensional (3D) printing, or additive manufacturing, is a group of innovative technologies that are increasingly employed for the production of 3D objects in different fields, including pharmaceutics, engineering, agri-food and medicines. The most processed materials by 3D printing techniques (e.g., fused deposition modelling, FDM; selective laser sintering, SLS; stereolithography, SLA) are polymeric materials since they offer chemical resistance, are low cost and have easy processability. However, one main drawback of using these materials alone (e.g., polylactic acid, PLA) in the manufacturing process is related to the poor mechanical and tensile properties of the final product. To overcome these limitations, fillers can be added to the polymeric matrix during the manufacturing to act as reinforcing agents. These include inorganic or organic materials such as glass, carbon fibers, silicon, ceramic or metals. One emerging approach is the employment of natural polymers (polysaccharides and proteins) as reinforcing agents, which are extracted from plants or obtained from biomasses or agricultural/industrial wastes. The advantages of using these natural materials as fillers for 3D printing are related to their availability together with the possibility of producing printed specimens with a smaller environmental impact and higher biodegradability. Therefore, they represent a “green option” for 3D printing processing, and many studies have been published in the last year to evaluate their ability to improve the mechanical properties of 3D printed objects. The present review provides an overview of the recent literature regarding natural polymers as reinforcing agents for 3D printing.

Recent advancement in 3-D printing: nanocomposites with added functionality

Three-Dimentional (3-D) printing is currently a popular printing technique that is used in many sectors. Potentially, this technology is expected to replace conventional manufacturing in the coming years. It is accelerating in gaining attention due to its design freedom where objects can be produced without imagination boundaries. The review presents a perspective on the application of 3-D printing application based on various fields. However, the ordinary 3-D printed products with a single type of raw often lack robustness leading to broken parts. Improving the mechanical property of a 3-D printed part is crucial for its applications in many fields. One of the promising solutions is to incorporate nanoparticles or fillers into the raw material. The review aims to provide information about the types of additive manufacturing. There are few types of raw materials can be used as foundation template in the printing, enhanced properties of the printed polymer nanocomposites with different types of nanoparticles as additives in the printing. The article reviews the advantages and disadvantages of different materials that are used as raw materials or base materials in 3-D printing. This can be a guideline for the readers to compare and analyse the raw materials prior to a decision on the type of material to be selected. The review prepares an overview for the researchers to choose the types of nanoparticles to be added in the printing of the products depending on the targeted application. With the added functionality of the 3-D polymer nanocomposites, it will help in widespread of the application of 3-D printing technology in various sector.

Stereolithography 3D printing technology in pharmaceuticals: a review

Three-dimensional printing (3DP) technology is an innovative tool used in manufacturing medical devices, producing alloys, replacing biological tissues, producing customized dosage forms and so on. Stereolithography (SLA), a 3D printing technique, is very rapid and highly accurate and produces finished products of uniform quality. 3D formulations have been optimized with a perfect tool of artificial intelligence learning techniques. Complex designs/shapes can be fabricated through SLA using the photopolymerization principle. Different 3DP technologies are introduced and the most promising of these, SLA, and its commercial applications, are focused on. The high speed and effectiveness of SLA are highlighted. The working principle of SLA, the materials used and applications of the technique in a wide range of different sectors are highlighted in this review. An innovative idea of 3D printing customized pharmaceutical dosage forms is also presented. SLA compromises several advantages over other methods, such as cost effectiveness, controlled integrity of materials and greater speed. The development of SLA has allowed the development of printed pharmaceutical devices. Considering the present trends, it is expected that SLA will be used along with conventional methods of manufacturing of 3D model. This 3D printing technology may be utilized as a novel tool for delivering drugs on demand. This review will be useful for researchers working on 3D printing technologies.

Minimally invasive gastrointestinal surgery: From past to the future

The improvement of the science and art of surgery began over 150 years ago. Surgical core tasks, “cutting and sewing” with hand and direct contact with the organs, have remained the same. However, in the 21st century, there has been a shifting paradigm in the methodology of surgery. The joint union between innovators, engineers, industry, and patient demands resulted in minimally invasive surgery (MIS). This method has influenced the techniques in every aspect of abdominal surgery, such as surgeons are not required to direct contact or see the structures on which they operate. Advances in the endoscope, imaging, and improved instrumentations convert the essential open surgery into the endoscopic method. Furthermore, computers and robotics show a promising future to facilitate complex procedures, enhance accuracy in microscale operations, and develop a simulation to improve the ability to face sophisticated approaches. MIS has been replacing open surgery due to improved survival, fewer complications, and rapid recoveries in recent years. Minimally invasive surgery's further research in diagnostic and therapeutic modalities is under investigation to achieve genuinely “noninvasive” surgery. Thus, MIS has gained interest in recent days and has been improving with promising outcomes.

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Minimally invasive surgery has interfered with multiple aspects of the surgical approach.

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Advancement in the endoscope, imaging, and other instrumentations shifting the current methodological conventional surgery.

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The benefit over risk is the promising primary outcome to achieve an exceptional quality of life.

Development of Multi-Compartment 3D-Printed Tablets Loaded with Self-Nanoemulsified Formulations of Various Drugs: A New Strategy for Personalized Medicine

This work aimed to develop a three-dimensional printed (3DP) tablet containing glimepiride (GLMP) and/or rosuvastatin (RSV) for treatment of dyslipidemia in patients with diabetes. Curcumin oil was extracted from the dried rhizomes of Curcuma longa and utilized to develop a self-nanoemulsifying drug delivery system (SNEDDS). Screening mixture experimental design was conducted to develop SNEDDS formulation with a minimum droplet size. Five different semi-solid pastes were prepared and rheologically characterized. The prepared pastes were used to develop 3DP tablets using extrusion printing. The quality attributes of the 3DP tablets were evaluated. A non-compartmental extravascular pharmacokinetic model was implemented to investigate the in vivo behavior of the prepared tablets and the studied marketed products. The optimized SNEDDS, of a 94.43 ± 3.55 nm droplet size, was found to contain 15%, 75%, and 10% of oil, polyethylene glycol 400, and tween 80, respectively. The prepared pastes revealed a shear-thinning of pseudoplastic flow behavior. Flat-faced round tablets of 15 mm diameter and 5.6–11.2 mm thickness were successfully printed and illustrated good criteria for friability, weight variation, and content uniformity. Drug release was superior from SNEDDS-based tablets when compared to non-SNEDDS tablets. Scanning electron microscopy study of the 3DP tablets revealed a semi-porous surface that exhibited some curvature with the appearance of tortuosity and a gel porous-like structure of the inner section. GLMP and RSV demonstrated relative bioavailability of 159.50% and 245.16%, respectively. Accordingly, the developed 3DP tablets could be considered as a promising combined oral drug therapy used in treatment of metabolic disorders. However, clinical studies are needed to investigate their efficacy and safety.

Tyrosol-Derived Biodegradable Inks with Tunable Properties for 3D Printing

Three-dimensional (3D) printing has emerged as a valuable tool in medicine over the past few decades. With a growing number of applications using this advanced processing technique, new polymer libraries with varied properties are required. Herein, we investigate tyrosol-based poly(ester-arylate)s as biodegradable inks in fused deposition modeling (FDM). Tyrosol-based polycarbonates and polyesters have proven to be useful biomaterials due to their excellent tunability, nonacidic degradation components, and the ability to be functionalized. Polymers are synthesized by polycondensation between a custom diphenol and commercially available diacids. Thermal properties, degradation rates, and mechanical properties are all tunable based on the diphenol and diacid chosen. Evaluation of material print as it relates to chemical structure, molecular weight, and thermal properties was explored. Higher-molecular-weight polymers greater than 50 kDa exhibit thermal degradation during printing and at some points are too viscous to print. It was determined that polymers with lower processing temperatures and molecular weights were printable regardless of the structure. An exception to this was pHTy6 that was printed at 65 kDa with minimal degradation. This is most likely due to its low melting temperature and, as a result, lower printing temperatures. Additionally, chemical improvements were made to incorporate thiol-alkene click chemistry as a means for postprint curing. Low-molecular-weight pHTy6 was end-capped with alkene functionality. This material was then formulated with either a dithiol for chain extension or tetrathiol for cross-linking. Scaffolds were cured after printing for 5, 15, 30 and 60 min intervals where longer cure times resulted in a tougher material. This design builds on the library of biologically active materials previously explored and aims to bring new biomaterials to the field of 3D-printed personal medicine.

Creation of Anatomically Correct and Optimized for 3D Printing Human Bones Models

Educational institutions in several countries state that the education sector should be modernized to ensure a contemporary, individualized, and more open learning process by introducing and developing advance digital solutions and learning tools. Visualization along with 3D printing have already found their implementation in different medical fields in Pauls Stradiņš Clinical University Hospital, and Rīga Stradiņš University, where models are being used for prosthetic manufacturing, surgery planning, simulation of procedures, and student education. The study aimed to develop a detailed methodology for the creation of anatomically correct and optimized models for 3D printing from radiological data using only free and widely available software. In this study, only free and cross-platform software from widely available internet sources has been used—“Meshmixer”, “3D Slicer”, and “Meshlab”. For 3D printing, the Ultimaker 5S 3D printer along with PLA material was used. In its turn, radiological data have been obtained from the “New Mexico Decedent Image Database”. In total, 28 models have been optimized and printed. The developed methodology can be used to create new models from scratch, which can be used will find implementation in different medical and scientific fields—simulation processes, anthropology, 3D printing, bioprinting, and education.

Mechanical Properties of Porous Structures for Dental Implants: Experimental Study and Computational Homogenization

A combined experimental and numerical study on titanium porous microstructures intended to interface the bone tissue and the solid homogeneous part of a modern dental implant is presented. A specific class of trabecular geometries is compared to a gyroid structure. Limitations associated with the application of the adopted selective laser melting technology to small microstructures with a pore size of 500 μm are first examined experimentally. The measured effective elastic properties of trabecular structures made of Ti6Al4V material support the computational framework based on homogenization with the difference between the measured and predicted Young’s moduli of the Dode Thick structure being less than 5%. In this regard, the extended finite element method is promoted, particularly in light of the complex sheet gyroid studied next. While for plastic material-based structures a close match between experiments and simulations was observed, an order of magnitude difference was encountered for titanium specimens. This calls for further study and we expect to reconcile this inconsistency with the help of computational microtomography.

3D Printing for Medical Applications: Current State of the Art and Perspectives during the COVID-19 Crisis

The coronavirus SARS-CoV-2 pandemic has affected over one hundred million people worldwide and has resulted in over two million deaths. In addition to the toll that coronavirus takes on the health of humans infected with the virus and the potential long term effects of infection, the repercussions of the pandemic on the economy as well as on the healthcare system have been enormous. The global supply of equipment necessary for dealing with the pandemic experienced extreme stress as healthcare systems around the world attempted to acquire personal protective equipment for their workers and medical devices for treating COVID-19. This review describes how 3D printing is currently being used in life saving surgeries such as heart and lung surgery and how 3D printing can address some of the worldwide shortage of personal protective equipment, by examining recent trends of the use of 3D printing and how these technologies can be applied during and after the pandemic. We review the use of 3D printed models for treating the long term effects of COVID-19. We then focus on methods for generating face shields and different types of respirators. We conclude with areas for future investigation and application of 3D printing technology.

3D Printed Intragastric Floating and Sustained-Release Tablets with Air Chambers

This work aimed to use hot-melt extrusion (HME) and dual fused deposition modeling (FDM) 3D printing technology to develop a novel intragastric floating and sustained-release drug delivery system. The intragastric floating and sustained-release tablet was engineered by employing hydroxypropyl methylcellulose (Affinisol^TM HPMC HME 15LV) for a drug-loaded core and polylactic acid (PLA) for an insoluble shell with an air chamber. Filaments for the drug-loaded core were compounded using a single-screw hot melt extruder. 3DMAX software was utilized to design a core with a complementary shell which consisted of a hollow chamber at the top and a drug-release window with different sizes (radius in 1.5, 2.5, 3, 3.5, 4.5 mm) at the bottom. Pharmaceutical characterization, solid dispersion evaluation, and drug release behavior were studied. The model drug in all formulations kept stable, and part of the drug in the extruded filaments and 3D printed tablets became amorphous. The introduction of an air chamber reduced the tablet density to below 0.9 g/cm³ and the 3D printed tablets floated immediately and continuously during the drug release process. The presence of the insoluble shell greatly prolonged the drug release time, and the drug release rate was positively correlated with the area of the release window. In addition, compared with shellless tablets, the 3D printed tablets with air chambers (radius in 4.5 mm) showed closer zero-order drug release for 24 h and released drug by diffusion-erosion combined mechanism. The developed intragastric floating and sustained-release tablets with air chambers could be applied to various drugs and provided a new way for the development of personalized drug delivery systems.

Transcending toward Advanced 3D-Cell Culture Modalities: A Review about an Emerging Paradigm in Translational Oncology

Cancer is a disorder characterized by an uncontrollable overgrowth and a fast-moving spread of cells from a localized tissue to multiple organs of the body, reaching a metastatic state. Throughout years, complexity of cancer progression and invasion, high prevalence and incidence, as well as the high rise in treatment failure cases leading to a poor patient prognosis accounted for continuous experimental investigations on animals and cellular models, mainly with 2D- and 3D-cell culture. Nowadays, these research models are considered a main asset to reflect the physiological events in many cancer types in terms of cellular characteristics and features, replication and metastatic mechanisms, metabolic pathways, biomarkers expression, and chemotherapeutic agent resistance. In practice, based on research perspective and hypothesis, scientists aim to choose the best model to approach their understanding and to prove their hypothesis. Recently, 3D-cell models are seen to be highly incorporated as a crucial tool for reflecting the true cancer cell microenvironment in pharmacokinetic and pharmacodynamics studies, in addition to the intensity of anticancer drug response in pharmacogenomics trials. Hence, in this review, we shed light on the unique characteristics of 3D cells favoring its promising usage through a comparative approach with other research models, specifically 2D-cell culture. Plus, we will discuss the importance of 3D models as a direct reflector of the intrinsic cancer cell environment with the newest multiple methods and types available for 3D-cells implementation.