Microtensile bond strength of resin cements to 3-D printed and milled temporary restorative resins / Resistencia de unión en microtracción de cementos resinosos a resinas para provisionales impresas y fresadas

Abstract To evaluate the microtensile bond strength (µTBS) of two resin cements to 3D printed and milled CAD/CAM resins used for provisional fixed partial dentures. Blocks (5 x 5 x 5 mm) of three 3D-printed resins (Cosmos3DTemp / Yller; Resilab3D Temp / Wilcos and SmartPrint BioTemp, / MMTech) were printed (Photon, Anycubic Technology Co.). A milled material (VitaCAD-Temp, VITA) was used as control. Half the specimens were sandblasted and the rest were untreated. Two blocks were bonded with the corresponding resin cement: PanaviaV5 (Kuraray Noritake) and RelyX Ultimate (3M Oral Care). After 24 hours, the bonded blocks were sectioned into 1 x 1 mm side sticks. Half the beams were tested for µTBS and the other half was thermocycled (5000 cycles, 30s dwell-time, 5s transfer time) before µTBS testing. A four way Generalized Linear Model (material*sandblasting*cement*aging) analysis was applied. VITA exhibited the lowest µTBS, regardless of the cement, sandblasting and thermocycling. Sandblasting significantly improved the µTBS of VIT, especially after aging, but did not improve the µTBS of 3D printed resins. Sandblasting was not beneficial for 3D printed resins, although is crucial for adhesive cementation of milled temporary resins. Airborne particle abrasion affects the integrity of 3D-printed resins, without producing a benefit on the microtensile bond strength of these materials. However, sandblasting is crucial to achieve a high bond strength on milled temporary resins.

Resumen Evaluar la resistencia adhesiva en microtracción (µTBS) de dos cementos resinosos a resinas CAD/CAM impresas y fresadas indicadas para restauraciones provisionales. Bloques (5 x 5 x 5mm) de tres resinas impresas (Cosmos3DTemp / Yller; Resilab3D Temp / Wilcos and SmartPrint BioTemp, / MMTech) y una resina fresada (VitaCAD-Temp, VITA) fueron fabricados. La mitad de los especímenes fueron arenados y el resto no recibió tratamiento mecánico. Dos bloques con condiciones de tratamiento iguales fueron cementados con cemento resinoso (PanaviaV5 / Kuraray Noritake y RelyX Ultimate / 3M Oral Care). Después de 24 horas los bloques fueron seccionados en palitos de 1 mm² de área. En la mitad de los especímenes se midió la TBS inmediatamente y el resto fue termociclado (5000 ciclos, 30s remojo, 5s transferencia) antes de la prueba de TBS. Se aplica un análisis estadístico por Modelo Linear General con 4 factores (material*arenado*cemento*termociclado). La resina VITA presentó la menor µTBS, independientemente del cemento usado, el arenado y el termociclado. Sin embargo, el arenado aumentó la µTBS de VIT, especialmente después del termociclado. Por otro lado, el arenado no resultó en un aumento significativo de la µTBS de las resinas impresas. El arenado no fue beneficiosos para las resinas impresas, aunque es un paso crucial para la cementación adhesive de las resinas fresadas. El arenado afecta la integridad de las capas de las resinas impresas, sin generar un beneficio en la TBS.

Evaluation of customized peripheral sealing device acceptance for surgical/medical masks among dental professionals during early COVID-19 pandemic / Evaluación de la aceptación de dispositivos de sellado periférico personalizados para máscaras quirúrgicas/médicas entre dentistas durante la pandemia temprana de COVID-19

Abstract A 3-dimensional (3D) printed custom-frame can improve the peripheral seal of readily available surgical/medical masks. This study aimed to assess the acceptance of a 3D-printed custom-frame with the American Society for Testing and Materials (ASTM) surgical/medical masks and the use of a face shield. A total of 206 subjects from a dental school participated, who answered a multiple-choice questionnaire. Participants received an invitation through the institutional email of the school via Qualtrics platform. 3D printed custom-frames were fabricated for each participant. According to their response, participants were divided into 4 groups: mask only (M), mask and frame (MF), mask and face shield (MFS), and all 3 personal protective equipment (MFFS). Data was analyzed in absolute and relative frequency. The acceptance of a 3D-printed custom-frame in the group MFFS varied between ''poor''/''very poor'' (44.7%). It allowed ''good'' performance of routine procedures (40.3%), but ''poor'' visual quality (48.1%). Musculoskeletal tolerance and ease to perform movements were adequate. There was no interference in olfactory sensitivity (44.7%) or in the ability to breathe (34.5%). Finally, it showed "moderate pain" (48.1%) on the ear and "no pain" (38.9%) on the head. The 3D-printed custom-frame adapted to ASTM surgical/medical face masks showed reasonable tolerance. Side effects of ear pain ranging in degrees were noted. Further research is indicated to evaluate safety, comfort, compliance, side effects, and occupational hazards of long-term use of enhanced PPE recommendations.Avoiding the recurrent outbreaks of COVID-19, the use of PPE by the public is necessary. Improper PPE use is a major source of concern for human and environmental health. Preventing such activities can be done by following steps involved in PPE disposals or by getting a new way to re-use such as improving peripherical sealing. Our work highlights that a custom-frame can improve protection, without adverse effects.

Resumen El sellado periférico de las máscaras médicas/quirúrgicas puede ser mejorado fácilmente mediante un marco personalizado impreso en 3 dimensiones (3D). Este estudio tuvo como objetivo evaluar la aceptación de un marco personalizado impreso en 3D cuando usado en combinacion con máscaras médicas/quirúrgicas de la Sociedad Estadounidense para Pruebas y Materiales (ASTM) asi como con el uso de protector facial. Participaron un total de 206 sujetos de una facultad de odontología, quienes respondieron un cuestionario de opción múltiple. Los participantes recibieron una invitación a través del correo institucional de la escuela a través de la plataforma Qualtrics. Se fabricaron marcos personalizados impresos en 3D para cada participante. Según su respuesta, los participantes se dividieron en 4 grupos: solo máscara (M), máscara y marco (MF), máscara y protector facial (MFS) y los 3 equipos de protección personal (MFFS). Los datos se analizaron en frecuencia absoluta y relativa. La aceptación de un marco personalizado impreso en 3D en el grupo MFFS varió entre ''pobre''/''muy pobre'' (44,7%). Permitió un ''buen'' desempeño de los procedimientos de rutina (40,3%), pero una ''mala'' calidad visual (48,1%). La tolerancia musculoesquelética y la facilidad para realizar movimientos fueron adecuadas. No hubo interferencia en la sensibilidad olfativa (44,7%) ni en la capacidad de respirar (34,5%). Finalmente, mostró "dolor moderado" (48,1%) en el oído y "sin dolor" (38,9%) en la cabeza. El marco personalizado impreso en 3D adaptado a las máscaras faciales quirúrgicas/ médicas de ASTM mostró una tolerancia razonable. Se observaron efectos secundarios de dolor de oído que variaron en grados. Estudios futuros deben evaluar la seguridad, la comodidad, efectos secundarios y los riesgos laborales del uso a largo plazo para este tipo de combinación. Para evitar los brotes recurrentes de COVID-19, es necesario el uso de equipamento personal de protección (EPP) por parte del público. El uso inadecuado de EPP es una fuente importante de preocupación para la salud humana y ambiental. La prevención de tales actividades se puede hacer siguiendo los pasos involucrados en la eliminación de EPP o obteniendo una nueva forma de reutilización, como mejorar el sellado periférico. Nuestro trabajo resalta que un marco personalizado puede mejorar la proteccion, sin afectos adversos.

Effect of 3D Printing Technology in Proximal Femoral Osteotomy in Children with Developmental Dysplasia of the Hip.

OBJECTIVE: To investigate the effect and safety of 3D printing technology in proximal femoral osteotomy in children with developmental dysplasia of the hip. METHODS: 40 cases of children with developmental dysplasia of the hip treated by pelvic osteotomy combined with proximal femoral osteotomy at Ningbo No. 6 Hospital from January 2017 to December 2019 were retrieved and retrospectively analyzed. Among them, 20 cases received preoperative measurement and design assisted by 3D printing technology (the 3D printing group), and 20 cases received conventional preoperative measurement and design (the conventional group). RESULTS: All patients were followed up for an average of 25 (12~36) months. During the follow-up, there were no complications such as infection, fracture of internal fixation, or malunion of osteotomy. Compared with the conventional group, the 3D printing group had a shorter operation time, less intraoperative blood loss, and fewer intraoperative X-ray fluoroscopies (all p < 0.05). In the last follow-up, the clinical efficacy was evaluated by the McKay standard: in the 3D printing group, 14 cases were excellent, 5 cases were good, and 1 case was fair. In the conventional group, 10 cases were excellent, 9 cases were good, and 1 case was fair (Z = -0.382, p > 0.05). CONCLUSION: Preoperative 3D printing of bilateral femur and other large physical models is accurate, which is ideal for the development of individual preoperative planning. Proximal femoral osteotomy using preoperative measurements and simulated surgical data improves the safety of the operation.

Active Materials for 3D Printing in Small Animals: Current Modalities and Future Directions for Orthopedic Applications.

The successful clinical application of bone tissue engineering requires customized implants based on the receiver's bone anatomy and defect characteristics. Three-dimensional (3D) printing in small animal orthopedics has recently emerged as a valuable approach in fabricating individualized implants for receiver-specific needs. In veterinary medicine, because of the wide range of dimensions and anatomical variances, receiver-specific diagnosis and therapy are even more critical. The ability to generate 3D anatomical models and customize orthopedic instruments, implants, and scaffolds are advantages of 3D printing in small animal orthopedics. Furthermore, this technology provides veterinary medicine with a powerful tool that improves performance, precision, and cost-effectiveness. Nonetheless, the individualized 3D-printed implants have benefited several complex orthopedic procedures in small animals, including joint replacement surgeries, critical size bone defects, tibial tuberosity advancement, patellar groove replacement, limb-sparing surgeries, and other complex orthopedic procedures. The main purpose of this review is to discuss the application of 3D printing in small animal orthopedics based on already published papers as well as the techniques and materials used to fabricate 3D-printed objects. Finally, the advantages, current limitations, and future directions of 3D printing in small animal orthopedics have been addressed.

3D printing of resilient biogels for omnidirectional and exteroceptive soft actuators.

Soft robotics greatly benefits from nature as a source of inspiration, introducing innate means of safe interaction between robotic appliances and living organisms. In contrast, the materials involved are often nonbiodegradable or stem from nonrenewable resources, contributing to an ever-growing environmental footprint. Furthermore, conventional manufacturing methods, such as mold casting, are not suitable for replicating or imitating the complexity of nature's creations. Consequently, the inclusion of sustainability concepts alongside the development of new fabrication procedures is required. We report a customized 3D-printing process based on fused deposition modeling, printing a fully biodegradable gelatin-based hydrogel (biogel) ink into dimensionally stable, complex objects. This process enables fast and cost-effective prototyping of resilient, soft robotic applications from gels that stretch to six times their original length, as well as an accessible recycling procedure with zero waste. We present printed pneumatic actuators performing omnidirectional movement at fast response times (less than a second), featuring integrated 3D-printed stretchable waveguides, capable of both proprio- and exteroception. These soft devices are endowed with dynamic real-time control capable of automated search-and-wipe routines to detect and remove obstacles. They can be reprinted several times or disposed of hazard-free at the end of their lifetime, potentially unlocking a sustainable future for soft robotics.

A Hybrid Titanium-Softmaterial, High-Strength, Transparent Cranial Window for Transcranial Injection and Neuroimaging.

A transparent and penetrable cranial window is essential for neuroimaging, transcranial injection and comprehensive understanding of cortical functions. For these applications, cranial windows made from glass coverslip, polydimethylsiloxane (PDMS), polymethylmethacrylate, crystal and silicone hydrogel have offered remarkable convenience. However, there is a lack of high-strength, high-transparency, penetrable cranial window with clinical application potential. We engineer high-strength hybrid Titanium-PDMS (Ti-PDMS) cranial windows, which allow large transparent area for in vivo two-photon imaging, and provide a soft window for transcranial injection. Laser scanning and 3D printing techniques are used to match the hybrid cranial window to different skull morphology. A multi-cycle degassing pouring process ensures a good combination of PDMS and Ti frame. Ti-PDMS cranial windows have a high fracture strength matching human skull bone, excellent light transmittance up to 94.4%, and refractive index close to biological tissue. Ti-PDMS cranial windows show excellent bio-compatibility during 21-week implantation in mice. Dye injection shows that the PDMS window has a "self-sealing" to keep liquid from leaking out. Two-photon imaging for brain tissues could be achieved up to 450 µm in z-depth. As a novel brain-computer-interface, this Ti-PDMS device offers an alternative choice for in vivo drug delivery, optical experiments, ultrasonic treatment and electrophysiology recording.

Uso de máquinas 3D e cortadores a laser em simulação aplicada à educação médica / Use of 3D printers and laser cutters for simulation in medical education

Introdução: As impressões tridimensionais (3D) têm obtido relevância em diversas áreas do conhecimento, especialmente na medicina. Com o advento da tecnologia, cada vez mais escolas médicas têm adotado o uso de prototipagem de estruturas humanas para aprimorar o treinamento dos estudantes, uma vez que a simulação produz um ambiente livre de riscos, no qual os alunos podem dominar com sucesso as habilidades relevantes para a prática clínica.Métodos: O projeto foi estruturado a partir da pesquisa dos softwares de impressão; seleção dos segmentos anatômicos a serem impressos; análise de materiais para a confecção; estudo aprofundado das caixas de simulação usadas no treinamento em videocirurgia e, por fim, realização de um treinamento dos estudantes interessados no desenvolvimento das habilidades cirúrgicas.Resultados: Por meio da impressão 3D,foram confeccionadas peças anatômicas para o ensino em anatomia, além de peças de silicone para treinamento de suturas manuais e videolaparoscópicas. O cortador a laser foi utilizado para fabricar caixas pretas, principalmente para simulações de cirurgia laparoscópica.Conclusão: A utilização de materiais 3D no ensino médico tem se mostrado altamente promissora, com aumento da curva de aprendizado dos alunos envolvidos e ótima relação custo-benefício. Contudo, o acesso a essa tecnologia ainda é restrito no Brasil, o que dificulta a expansão do método para todas as escolas médicas nacionais.

Introduction: Three-dimensional (3D) printing has become relevant in several areas of knowledge, especially Medicine. With the advent of technology, medical schools started using prototypes of human structures to improve student training, given that simulation provides a risk-free environment where students can successfully master relevant skills for clinical practice.Methods: The present study consisted of research about printing software, selection of anatomical segments for printing, analysis of printing materials, study of simulation boxes used in video-assisted surgery training, and training of students interested in developing surgical skills.Results: 3D printing was used to fabricate anatomical models for teaching anatomy and silicone models for manual and video-assisted laparoscopic suture training. Laser cutters were used to manufacture black boxes, mainly for laparoscopy simulation. Conclusion: The use of 3D printing in medical education is highly promising, with an improved learning curve among students and an excellent benefit-cost ratio. However, access to this technology is still limited in Brazil, which makes it difficult to expand the method to all national medical schools.

The Use of Bio-Inks and the Era of Bioengineering and Tooth Regeneration

Abstract Objective: To review existing literature and provide an update on the current use of Bio-Inks and potential future use. Material and Methods: A MeSH keyword search was conducted to find out relevant articles for this short review. Results: Bio inks used in 3D printing grafting require various properties essential for the selection. Combining multiple methods and improved properties is essential for developing successful bio-inks for 3D grafting of functional tissues and tooth pulp regeneration from stem cells. To date, researchers have made many efforts to grow teeth based on stem cells and inculcate regeneration of teeth along with surrounding tissues like alveolar bones and periodontal ligaments. Conclusion: 3D printing with Bio-Inks requires strict adherence to safety protocols for successful outcomes, making it difficult to employ this routinely.

Three-dimensional printing of orbital computed tomography scan images for use in ophthalmology teaching / Impressão tridimensional de imagens médicas de tomografia computadorizada para uso no ensino de oftalmologia

ABSTRACT Introduction: The use of tridimensional (3D) printing in healthcare has contributed to the development of instruments and implants. The 3D printing has also been used for teaching future professionals. In order to have a good 3D printed piece, it is necessary to have high quality images, such as the ones from Computerized Tomography (CT scan) exam, which shows the anatomy from different cuts and allows for a good image reconstruction. Purpose: To propose a protocol for creating digital files from computerized tomography images to be printed in 3D and used as didactic material in the ophthalmology field, using open-source software, InVesalius®, Blender® and Repetier-Host©. Methods: Two orbit CT scan exam images in the DICOM format were used to create the virtual file to be printed in 3D. To edit the images, the software InVesalius® (Version 3.1.1) was used to delimit and clean the structure of interest, and also to convert to STL format. The software Blender® (Version 2.80) was used to refine the image. The STL image was then sent to the Repetier-Host© (Version 2.1.3) software, which splits the image in layers and generates the instructions to print the piece in the 3D printer using the polymer polylactic acid (PLA). Results: The printed anatomical pieces printed reproduced most structures, both bone and soft structures, satisfactorily. However, there were some problems during printing, such as the loss of small bone structures, that are naturally surrounded by muscles due to the lack of support. Conclusion: Despite the difficulties faced during the production of the pieces, it was also possible to reproduce the anatomical structures adequately, which indicates that this protocol of 3D printing from medical images is viable.

RESUMO Introdução: O uso de impressão em 3-D na área da saúde tem contribuído para o desenvolvimento de instrumentos e próteses. A impressão 3-D tem sido usada para o ensino de futuros profissionais. Para se alcançar uma boa peça em 3-D, é necessário ter imagens de alta qualidade, como aquelas geradas pelo exame de Tomografia Computadorizada (TC), que mostra a anatomia sob diferentes cortes e permite uma boa reconstrução de imagem. Objetivo: Propor um protocolo para a criação de arquivos digitais a partir de imagens de tomografia computadorizada a serem impressas em 3-D e usadas como modelo de material didático oftalmológico usando software de código aberto, InVesalius®, Bender® e Repetier-Host©. Métodos: Foram utilizadas imagens em formato DICOM provenientes de dois exames de tomografia computadorizada de órbitas para a impressão tridimensional. Para manuseio das imagens, foram utilizados o InVesalius®, versão 3.1.1, para delimitar e limpar a estrutura de interesse e também para converter em formato STL. O Blender®, versão 2.80 foi usado para refinamento. A imagem em STL foi então enviada para o programa Repetier-Host, versão 2.1.3, que divide a imagem em camadas e gera as instruções para impressão da peça em ácido polilático na impressora tridimensional. Resultados: As peças anatômicas impressas reproduziram de forma satisfatória a maioria das estruturas ósseas e musculares. No entanto, houve dificuldade durante a impressão das estruturas ósseas menores, como perda de estrutura óssea pequena, que não possuíam sustentação, por serem envoltas pelo músculo. Conclusão: Apesar das dificuldades encontradas na produção dessas peças de estudo, foi possível reproduzir estruturas com fidelidade, indicando que o protocolo proposto viabiliza a impressão de imagens oriundas da tomografia computadorizada para impressão tridimensional.

Clinical Applications of Additive Manufacturing Models in Neurosurgery: a Systematic Review

Introduction Three-dimensional (3D) printing technologies provide a practical and anatomical way to reproduce precise tailored-made models of the patients and of the diseases. Those models can allow surgical planning, besides training and surgical simulation in the treatment of neurosurgical diseases. Objective The aim of the present article is to review the scenario of the development of different types of available 3D printing technologies, the processes involved in the creation of biomodels, and the application of those advances in the neurosurgical field. Methods We searched for papers that addressed the clinical application of 3D printing in neurosurgery on the PubMed, Ebsco, Web of Science, Scopus, and Science Direct databases. All papers related to the use of any additivemanufacturing technique were included in the present study. Results Studies involving 3D printing in neurosurgery are concentrated on threemain areas: (1) creation of anatomical tailored-made models for planning and training; (2) development of devices and materials for the treatment of neurosurgical diseases, and (3) biological implants for tissues engineering. Biomodels are extremely useful in several branches of neurosurgery, and their use in spinal, cerebrovascular, endovascular, neuro-oncological, neuropediatric, and functional surgeries can be highlighted. Conclusions Three-dimensional printing technologies are an exclusive way for direct replication of specific pathologies of the patient. It can identify the anatomical variation and provide a way for rapid construction of training models, allowing the medical resident and the experienced neurosurgeon to practice the surgical steps before the operation.

Projection-based stereolithography for direct 3D printing of heterogeneous ultrasound phantoms.

Modern ultrasound (US) imaging is increasing its clinical impact, particularly with the introduction of US-based quantitative imaging biomarkers. Continued development and validation of such novel imaging approaches requires imaging phantoms that recapitulate the underlying anatomy and pathology of interest. However, current US phantom designs are generally too simplistic to emulate the structure and variability of the human body. Therefore, there is a need to create a platform that is capable of generating well-characterized phantoms that can mimic the basic anatomical, functional, and mechanical properties of native tissues and pathologies. Using a 3D-printing technique based on stereolithography, we fabricated US phantoms using soft materials in a single fabrication session, without the need for material casting or back-filling. With this technique, we induced variable levels of stable US backscatter in our printed materials in anatomically relevant 3D patterns. Additionally, we controlled phantom stiffness from 7 to >120 kPa at the voxel level to generate isotropic and anisotropic phantoms for elasticity imaging. Lastly, we demonstrated the fabrication of channels with diameters as small as 60 micrometers and with complex geometry (e.g., tortuosity) capable of supporting blood-mimicking fluid flow. Collectively, these results show that projection-based stereolithography allows for customizable fabrication of complex US phantoms.

Bioprinting of Cartilage with Bioink Based on High-Concentration Collagen and Chondrocytes.

The study was aimed at the applicability of a bioink based on 4% collagen and chondrocytes for de novo cartilage formation. Extrusion-based bioprinting was used for the biofabrication. The printing parameters were tuned to obtain stable material flow. In vivo data proved the ability of the tested bioink to form a cartilage within five to six weeks after the subcutaneous scaffold implantation. Certain areas of cartilage formation were detected as early as in one week. The resulting cartilage tissue had a distinctive structure with groups of isogenic cells as well as a high content of glycosaminoglycans and type II collagen.

Clinical Applications of Meshed Multilayered Anatomical Models by Low-Cost Three-Dimensional Printer.

SUMMARY: In recent years, even low-cost fused deposition modeling-type three-dimensional printers can be used to create a three-dimensional model with few errors. The authors devised a method to create a three-dimensional multilayered anatomical model at a lower cost and more easily than with established methods, by using a meshlike structure as the surface layer. Fused deposition modeling-type three-dimensional printers were used, with opaque polylactide filament for material. Using the three-dimensional data-editing software Blender (Blender Foundation, www.blender.org) and Instant Meshes (Jakob et al., https://igl.ethz.ch/projects/instant-meshes/) together, the body surface data were converted into a meshlike structure while retaining its overall shape. The meshed data were printed together with other data (nonmeshed) or printed separately. In each case, the multilayer model in which the layer of the body surface was meshed could be output without any trouble. It was possible to grasp the positional relationship between the body surface and the deep target, and it was clinically useful. The total work time for preparation and processing of three-dimensional data ranged from 1 hour to several hours, depending on the case, but the work time required for converting into a meshlike shape was about 10 minutes in all cases. The filament cost was $2 to $8. In conclusion, the authors devised a method to create a three-dimensional multilayered anatomical model to easily visualize positional relationships within the structure by converting the surface layer into a meshlike structure. This method is easy to adopt, regardless of the available facilities and economic environment, and has broad applications.

Evaluation of the Usability of a Low-Cost 3D Printer in a Tissue Engineering Approach for External Ear Reconstruction.

The use of alloplastic materials instead of autologous cartilage grafts offers a new perspective in craniofacial reconstructive surgery. Particularly for regenerative approaches, customized implants enable the surgeon to restore the cartilaginous framework of the ear without donor site morbidity. However, high development and production costs of commercially available implants impede clinical translation. For this reason, the usability of a low-cost 3D printer (Ultimaker 2+) as an inhouse-production tool for cheap surgical implants was investigated. The open software architecture of the 3D printer was modified in order to enable printing of biocompatible and biologically degradable polycaprolactone (PCL). Firstly, the printing accuracy and limitations of a PCL implant were compared to reference materials acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Then the self-made PCL-scaffold was seeded with adipose-tissue derived stem cells (ASCs), and biocompatibility was compared to a commercially available PCL-scaffold using a cell viability staining (FDA/PI) and a dsDNA quantification assay (PicoGreen). Secondly, porous and solid patient-customized ear constructs were manufactured from mirrored CT-imagining data using a computer-assisted design (CAD) and computer-assisted manufacturing (CAM) approach to evaluate printing accuracy and reproducibility. The results show that printing of a porous PCL scaffolds was possible, with an accuracy equivalent to the reference materials at an edge length of 10 mm and a pore size of 0.67 mm. Cell viability, adhesion, and proliferation of the ASCs were equivalent on self-made and the commercially available PCL-scaffolds. Patient-customized ear constructs could be produced well in solid form and with limited accuracy in porous form from all three thermoplastic materials. Printing dimensions and quality of the modified low-cost 3D printer are sufficient for selected tissue engineering applications, and the manufacturing of personalized ear models for surgical simulation at manufacturing costs of EUR 0.04 per cell culture scaffold and EUR 0.90 (0.56) per solid (porous) ear construct made from PCL. Therefore, in-house production of PCL-based tissue engineering scaffolds and surgical implants should be further investigated to facilitate the use of new materials and 3D printing in daily clinical routine.

Etched fiber Bragg grating probe using a regular CNC machine and a 3D printer.

Etched fiber Bragg gratings (EFBGs) have been widely employed for refractive index (RI) measurements that can be used to monitor sugar consumption during the fermentation of alcoholic beverages. EFBGs are obtained by removing the cladding of a fiber Bragg grating, which is traditionally performed by a chemical attack with hydrogen fluoride, an extremely hazardous corrosive substance that causes severe wounds and even death. To overcome such drawbacks, this technical note presents a simple, practical, and low cost method for the diameter reduction of single mode optical fibers by mechanical polishing, employing a small scale computer numerical control device and an ad hoc 3D-printed rod. The sensor probe obtained was tested using sucrose aqueous solutions with RIs between 1.333 and 1.394, measured in an Abbe refractometer. The results show a linear shift of the Bragg wavelength with respect to RI with a correlation of 0.928.

Role of Human Primary Renal Fibroblast in TGF-ß1-Mediated Fibrosis-Mimicking Devices.

Renal fibrosis is a progressive chronic kidney disease that ultimately leads to end-stage renal failure. Despite several approaches to combat renal fibrosis, an experimental model to evaluate currently available drugs is not ideal. We developed fibrosis-mimicking models using three-dimensional (3D) co-culture devices designed with three separate layers of tubule interstitium, namely, epithelial, fibroblastic, and endothelial layers. We introduced human renal proximal tubular epithelial cells (HK-2), human umbilical-vein endothelial cells, and patient-derived renal fibroblasts, and evaluated the effects of transforming growth factor-ß (TGF-ß) and TGF-ß inhibitor treatment on this renal fibrosis model. The expression of the fibrosis marker alpha smooth muscle actin upon TGF-ß1 treatment was augmented in monolayer-cultured HK-2 cells in a 3D disease model. In the vascular compartment of renal fibrosis models, the density of vessels was increased and decreased in the TGF-ß-treated group and TGF-ß-inhibitor treatment group, respectively. Multiplex ELISA using supernatants in the TGF-ß-stimulating 3D models showed that pro-inflammatory cytokine and growth factor levels including interleukin-1 beta, tumor necrosis factor alpha, basic fibroblast growth factor, and TGF-ß1, TGF-ß2, and TGF-ß3 were increased, which mimicked the fibrotic microenvironments of human kidneys. This study may enable the construction of a human renal fibrosis-mimicking device model beyond traditional culture experiments.

Preoperative Planning Using 3D Printing Technology in Orthopedic Surgery.

The applications of 3D printing technology in health care, particularly orthopedics, continue to broaden as the technology becomes more advanced, accessible, and affordable worldwide. 3D printed models of computed tomography (CT) and magnetic resonance image (MRI) scans can reproduce a replica of anatomical parts that enable surgeons to get a detailed understanding of the underlying anatomy that he/she experiences intraoperatively. The 3D printed anatomic models are particularly useful for preoperative planning, simulation of complex orthopedic procedures, development of patient-specific instruments, and implants that can be used intraoperatively. This paper reviews the role of 3D printing technology in orthopedic surgery, specifically focusing on the role it plays in assisting surgeons to have a better preoperative evaluation and surgical planning.

3D bioprinted silk fibroin hydrogels for tissue engineering.

The development of biocompatible and precisely printable bioink addresses the growing demand for three-dimensional (3D) bioprinting applications in the field of tissue engineering. We developed a methacrylated photocurable silk fibroin (SF) bioink for digital light processing 3D bioprinting to generate structures with high mechanical stability and biocompatibility for tissue engineering applications. Procedure 1 describes the synthesis of photocurable methacrylated SF bioink, which takes 2 weeks to complete. Digital light processing is used to fabricate 3D hydrogels using the bioink (1.5 h), which are characterized in terms of methacrylation, printability, mechanical and rheological properties, and biocompatibility. The physicochemical properties of the bioink can be modulated by varying photopolymerization conditions such as the degree of methacrylation, light intensity, and concentration of the photoinitiator and bioink. The versatile bioink can be used broadly in a range of applications, including nerve tissue engineering through co-polymerization of the bioink with graphene oxide, and for wound healing as a sealant. Procedure 2 outlines how to apply 3D-printed SF hydrogels embedded with chondrocytes and turbinate-derived mesenchymal stem cells in one specific in vivo application, trachea tissue engineering, which takes 2-9 weeks.

Emergent Biological Endurance Depends on Extracellular Matrix Composition of Three-Dimensionally Printed Escherichia coli Biofilms.

Biofilms are three-dimensional (3D) bacterial communities that exhibit a highly self-organized nature in terms of their composition and complex architecture. Bacteria in biofilms display emergent biological properties, such as resistance to antimicrobials and disinfectants that the individual planktonic cells lack. Bacterial biofilms possess specialized architectural features including unique extracellular matrix compositions and a distinct spatially patterned arrangement of cells and matrix components within the biofilm. It is unclear which of these architectural elements of bacterial biofilms lead to the development of their emergent biological properties. Here, we report a 3D printing-based technique for studying the emergent resistance behaviors of Escherichia coli biofilms as a function of their architecture. Cellulose and curli are the major extracellular-matrix components in E. coli biofilms. We show that 3D-printed biofilms expressing either curli alone or both curli and cellulose in their extracellular matrices show higher resistance to exposure against disinfectants than 3D prints expressing either cellulose alone or no biofilm-matrix components. The 3D-printed biofilms expressing cellulose and/or curli also show thicker anaerobic zones than nonbiofilm-forming E. coli 3D prints. Thus, the matrix composition plays a crucial role in the emergent spatial patterning and biological endurance of 3D-printed biofilms. In contrast, initial spatial distribution of bacterial density or curli-producing cells does not have an effect on biofilm resistance phenotypes. Further, these 3D-printed biofilms could be reversibly attached to different surfaces (bacterial cellulose, glass, and polystyrene) and display resistance to physical distortions by retaining their shape and structure. This physical robustness highlights their potential in applications including bioremediation, protective coatings against pathogens on medical devices, or wastewater treatment, among many others. This new understanding of the emergent behavior of bacterial biofilms could aid in the development of novel engineered living materials using synthetic biology and materials science approaches.

Transdermal vaccination via 3D-printed microneedles induces potent humoral and cellular immunity.

Vaccination is an essential public health measure for infectious disease prevention. The exposure of the immune system to vaccine formulations with the appropriate kinetics is critical for inducing protective immunity. In this work, faceted microneedle arrays were designed and fabricated utilizing a three-dimensional (3D)-printing technique called continuous liquid interface production (CLIP). The faceted microneedle design resulted in increased surface area as compared with the smooth square pyramidal design, ultimately leading to enhanced surface coating of model vaccine components (ovalbumin and CpG). Utilizing fluorescent tags and live-animal imaging, we evaluated in vivo cargo retention and bioavailability in mice as a function of route of delivery. Compared with subcutaneous bolus injection of the soluble components, microneedle transdermal delivery not only resulted in enhanced cargo retention in the skin but also improved immune cell activation in the draining lymph nodes. Furthermore, the microneedle vaccine induced a potent humoral immune response, with higher total IgG (Immunoglobulin G) and a more balanced IgG1/IgG2a repertoire and achieved dose sparing. Furthermore, it elicited T cell responses as characterized by functional cytotoxic CD8+ T cells and CD4+ T cells secreting Th1 (T helper type 1)-cytokines. Taken together, CLIP 3D-printed microneedles coated with vaccine components provide a useful platform for a noninvasive, self-applicable vaccination.