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Objective Based on 3D printing technology, explore the precision of a perforator vessel location guide plate for fibular musculocutaneous flaps before the transplantation of fibular osteocutaneous flaps and evaluate its application effects. Methods This study was reviewed and approved by the ethics committee, and informed consent was obtained from the patients. From May 2019 to October 2022, 14 patients with jaw defects who needed to undergo fibular perforator flap transplantation at the First Affiliated Hospital of Xinjiang Medical University were selected. For the seven patients in the guide plate group, CTA was combined with Mimics software to reconstruct both lower limbs, and the perforator vessel positioning guide for locating perforator vessels was designed; the two ends of the guide plate were designed as fixed ends, with the upper end fixed to the knee joint and the lower end fixed to the ankle joint, and the guide plate was fabricated by a 3D printer. For the seven patients in the control group, a conventional handheld Doppler probe was used for perforator vessel location. The average operation time, bleeding volume, recovery time, deviation of perforator vessel location, postoperative flap-related complications, postoperative donor site shape satisfaction, and lower extremity functional scale (LEFS) score were recorded. SPSS 25.0 software was used for statistical analysis. Results The average operation time, bleeding volume, recovery time, deviation of perforator vessel location and postoperative donor site shape satisfaction were significantly better in the guide plate group than in the control group (PP>0.05). Conclusion Based on 3D printing technology, fibular musculocutaneous flap perforator vessels can be more accurately located using a guide plate and the knee and ankle as fixed points, and this method can effectively stabilize the guide position, prevent soft tissue offset, and improve positioning accuracy and thus deserves to be generalized.

Abstract Background The responsible use of 3D-printing in medicine includes a context-based quality assurance. Considerable literature has been published in this field, yet the quality of assessment varies widely. The limited discriminatory power of some assessment methods challenges the comparison of results. The total error for patient specific anatomical models comprises relevant partial errors of the production process: segmentation error (SegE), digital editing error (DEE), printing error (PrE). The present review provides an overview to improve the general understanding of the process specific errors, quantitative analysis, and standardized terminology. Methods This review focuses on literature on quality assurance of patient-specific anatomical models in terms of geometric accuracy published before December 4th, 2022 (n = 139). In an attempt to organize the literature, the publications are assigned to comparable categories and the absolute values of the maximum mean deviation (AMMD) per publication are determined therein. Results The three major examined types of original structures are teeth or jaw (n = 52), skull bones without jaw (n = 17) and heart with coronary arteries (n = 16). VPP (vat photopolymerization) is the most frequently employed basic 3D-printing technology (n = 112 experiments). The median values of AMMD (AMMD: The metric AMMD is defined as the largest linear deviation, based on an average value from at least two individual measurements.) are 0.8 mm for the SegE, 0.26 mm for the PrE and 0.825 mm for the total error. No average values are found for the DEE. Conclusion The total error is not significantly higher than the partial errors which may compensate each other. Consequently SegE, DEE and PrE should be analyzed individually to describe the result quality as their sum according to rules of error propagation. Current methods for quality assurance of the segmentation are often either realistic and accurate or resource efficient. Future research should focus on implementing models for cost effective evaluations with high accuracy and realism. Our system of categorization may be enhancing the understanding of the overall process and a valuable contribution to the structural design and reporting of future experiments. It can be used to educate specialists for risk assessment and process validation within the additive manufacturing industry. Graphical Abstract Context of the figures in this review. Center: Fig. 5+ 7; top (blue): Fig. 8; right (green): Fig. 9; bottom (yellow): Fig. 10; left (red): Fig. 11. A version in high resolution can be found online in the supplementary material.

Abstract Background The aim of the study was to determine and compare the biaxial flexural strength (BFS) and Vickers hardness (VHN) of additive and subtractive manufactured permanent composite-based restorative materials, before and after thermal aging. Methods A total of 200 specimens were prepared; 100 disc-shaped specimens (diameter 13 × 1.2 mm) for the BFS test and 100 square specimens (14 × 14 × 2 mm) for the VHN test. The specimens were made from various materials: two subtractive composite-based blocks (Cerasmart 270 [CS], Vita Enamic [VE]), two additive composite-based resins used for two different vat polymerization methods (digital light processing [DLP]; Saremco Print Crowntec [SC] and stereolithography [SLA]; Formlabs Permanent Crown Resin [FP]), and one feldspathic glass-matrix ceramic block (Vita Mark II [VM]) as the control group. Specimens of each material were divided into two subgroups: thermal cycled or non-thermal cycled (n = 10). BFS and VHN tests were performed on all groups. Data were analyzed with two-way ANOVA and post hoc Tukey test (α = 0.05). Results The type of restorative material used for the specimen had a statistically significant influence on both BFS and VHN values. However, thermal cycling did not affect the BFS and VHN values. After thermal cycling, the results of the BFS test were ranked from best to worst as follows: CS, FP, SC, VE, then VM. For the VHN values, the order from best to worst was as follows: VM, VE, CS, FP, then SC. Conclusions 3D printed and milled composite groups showed higher BFS than feldspathic ceramics. When the VHN results were examined, it was seen that the 3D resin groups had the lowest VHN values. Furthermore, it was observed that the thermal cycle had no effect on BFS or VHN.

Access to clean drinking water remains a challenge in many developing countries, emphasizing the critical need for affordable, scalable and sustainable water treatment technologies. This study employs an electrochemical flow cell incorporating a 3D-printed biomimetic flow field for efficient in situ electrochlorination, avoiding water recirculation or external chloride dosing. The impact of varied ionic compositions of groundwater on electrochlorination efficiency is examined using synthetic groundwater samples, reflecting diverse hydrogeological conditions within a region in a developing country. Employing a Multilevel Factorial Design (MFD), the study highlights the significant influence of water ionic composition, flow rate, and applied current on free chlorine production. The results affirm the capability of the reactor to generate free chlorine species in a range of 0.32–6.13 mg·L−1. The specific energy consumptions oscillate between 0.49 and 19.67 Wh·mg−1 for chloride concentration in the samples ranging from 24 to 146 mg·L−1. This confirms the potential of the suggested electrochemical cell design for broad use in the studied region, and possibly in similar settings worldwide.

Molecular diagnosis is a gold standard method for identifying an infectious disease. DNA extraction from a target pathogen is one of the most important procedures for accurate analysis of the disease-causative pathogen. In this study, a novel 3D-printed electrophoretic DNA extraction microdevice (3D-EDEM) was developed using a digital light processing-stereolithography (DLP-SL) for point-of-care analysis. The 3D-EDEM consists of a source chamber for a bacteria lysate reservoir, a sink chamber for an elution solution container, a hydrogel channel embracing capillary channels that act as a sieving matrix for size-based separation, and two electrode holders for supplying electrical current. Prior to fabricating the 3D-EDEM, UV-curable resin was prepared by using a poly(ethylene glycol) diacrylate (PEG-DA), Irgarcure 819 (IRG), and 2-isopropyl thioxanthone (ITX) as a monomer, a photoinitiator, and a photosensitizer, respectively. The 3D-printed 3D-EDEM provides numerous merits of being inexpensive, reproducible, and convenient, making it more suitable for on-site DNA extraction microdevices than soft-lithographic procedures. For DNA extraction on the 3D-EDEM, Escherichia coli O157:H7 (E. coli) lysate and elution buffer were loaded into the source chamber and the sink chamber, respectively. The optimum DNA extraction time and limit of the DNA extraction test of 3D-EDEM were carried out to evaluate DNA extraction performance, especially using a portable battery. Additionally, the successful DNA extraction test from artificially infected food samples confirms the applicability of the 3D-EDEM to real fields. The proposed 3D-EDEM is adequate for on-site DNA extraction in the field of clinical diagnosis, food safety, environmental monitoring, and forensic analysis.

In the context of experimental optics- and photonics-research, motorized, high-precision rotation stages are an integral part of almost every laboratory setup. Nevertheless, their availability in the laboratory is limited due to the relatively high acquisition costs in the range of several 1000€ and is often supplemented by manual rotation stages. If only a single sample is to be analyzed repeatedly at two different angles or the polarization of a laser source is to be rotated, this approach is understandable. Yet, in the context of automation and the associated gain in measurement time, cost-effective and precise rotation stages designed for the use of optics are lacking.We present a low-cost alternative of a motorized high precision rotation stage system. The design is based on a combination of 3D-printed components, which form the monolithic mechanical framework, and a stepper motor controlled by an ESP32 based microcontroller. By coupling the motor and rotation unit via a toothed belt, backlash is minimized and at the same time high positioning accuracy can be achieved. Finally, the implementation of remote procedure calls for serial communication and the utilization of a physical home switch and incremental encoder complete the desired feature set of an integrated system for laboratory setups. The total costs can thus be reduced to less than 100€ without significantly restricting the performance criteria.

ABSTRACTThis paper investigates the use of architected cellular and solid designs of materials via additive manufacturing and in-situ CO2 circulation to augment the carbonation and mechanical properties of a calcium silicate-based cement (CSC) binder. A wollastonite-based binder was formulated for extrusion-based 3D-printing. Solid and cellular lamellar architectures were designed to probe the role of layered interfaces and higher surface area on the degree of carbonation (DOC), respectively. Two carbonation exposure scenarios, with and without in-situ carbonation were employed. The DOC, microstructural phases, and flexural strength were characterised using TGA, modified over-flow image analysis technique, and three-point-bending, respectively. By exploiting 3D-printing and harnessing the higher surface area of cellular architecture, the material obtained a significantly higher DOC (by 8.9-folds) and flexural strength (by 5.7-folds) compared to reference cast. In-situ carbonation of cellular architected materials can additionally improve early-stage deformation, DOC (by 12.9-folds) and flexural strength (by 16.5-folds), compared to cast.

Heterogenization of Eosin Y by 3D‐printing and its application in photocatalysis are reported. The approach allows a fine tuning of the photocatalyst morphology and its rapid preparation. Photocatalytic activity was evaluated through model organic reactions involving oxidation, reduction, and photosensitization pathways. The efficiency, recyclability and stability of 3D printed EY is remarkable paving the way to new generation of heterogeneous photocatalysts with a perfect control of their shape and adaptable to any photoreactors. [ABSTRACT FROM AUTHOR]

(1) Background: Orthopedic surgery has been transformed by 3D-printed personalized instruments (3DP-PSIs), which enhance precision and reduce complications. Hospitals are adopting in-house 3D printing facilities, using cost-effective methods like Fused Deposition Modeling (FDM) with materials like Polylactic acid (PLA) to create 3DP-PSI. PLA's temperature limitations can be overcome by annealing High-Temperature PLA (ann-HTPLA), enabling steam sterilization without compromising properties. Our study examines the in vivo efficacy of ann-HTPLA 3DP-PSI in pediatric orthopedic surgery. (2) Methods: we investigated safety and efficacy using ann-HTPLA 3DP-PSI produced at an "in-office" 3D-printing Point-of-Care (3DP-PoC) aimed at correcting limb deformities in pediatric patients. Data on 3DP-PSI dimensions and printing parameters were collected, along with usability and complications. (3) Results: Eighty-three ann-HTPLA 3DP-PSIs were utilized in 33 patients (47 bone segments). The smallest guide used measured 3.8 cm3, and the largest measured 58.8 cm3. Seventy-nine PSIs (95.2%; 95% C.I.: 88.1–98.7%) demonstrated effective use without issues. Out of 47 procedures, 11 had complications, including 2 infections (4.3%; 95% CI: 0.5–14.5%). Intraoperative use of 3DP-PSIs did not significantly increase infection rates or other complications. (4) Conclusions: ann-HTPLA has proven satisfactory usability and safety as a suitable material for producing 3DP-PSI in an "in-office" 3DP-PoC. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing has paved the way in pharmaceutical applications. This innovative methodology presents novel and inventive remedies for patients and the pharmaceutical sector. Moreover, the benefits of this approach encompass the mitigation of adverse effects, customization of formulations for patients with rare medical conditions, and enhancement of therapeutic effectiveness. The objective of our review was to offer a comprehensive survey of the advancements observed in the drug delivery systems that were produced. A thorough inspection has assessed the diverse dosage forms developed using the three-dimensional printing technique (3DP), especially in the last five years. The pharmaceutical industry places significant emphasis on the benefits of developing dosage forms with intricate designs and geometries, incorporating multiple active ingredients, and tailored release profiles due to their versatility and related advantages. Drug delivery systems can be classified into different modalities, tablets, capsules, suppositories, transdermal delivery systems, microneedles, vaginal delivery systems, and nanoscale dosage forms. The utilization of our classification system facilitates researchers' task of evaluating publications and effectively pinpointing further opportunities for research exploration. [ABSTRACT FROM AUTHOR]

Although lipid‐based formulations are an attractive approach for enhancing the oral bioavailability of lipophilic drugs, their addition into solid oral dosage forms has been proven challenging due to their high viscosity and heat sensitivity. Therefore, unlike the traditional tableting process, this study employed semi‐solid extrusion 3D‐printing to produce–at room temperature–gastro‐resistant printlets containing a high percentage of bioactive lipids for the effective delivery of lipophilic drugs through self‐emulsification. The bio‐compatible lipidic mesophase ink, owing to a tunable 3D nanostructure, is employed as a starting material to produce printlets via additive manufacturing. An active lipid mixture – with antifibrotic properties – is blended with the antioxidant vitamin E and water, and the ink printability is optimized by carefully tailoring its composition, and thus its phase identity. The obtained printlets disintegrated upon contact with intestinal fluids forming colloidal structures that enhanced the solubility of a poorly water‐soluble drug. The printlets exhibited antifibrotic activity on human hepatic stellate cells, LX‐2, suggesting that the generated self‐emulsified colloidal structures made both the fibrosis‐resolving bioactive excipients and the drug promptly available, enhancing their cell uptake and, in turn, their therapeutic activity. [ABSTRACT FROM AUTHOR]

Digital fabrication, like 3D printing, is a new opportunity for rehabilitation professionals to produce customized assistive devices. It allows for empowerment and collaboration in device procurement, but practical implementations are scarcely described. We describe the workflow, discuss feasibility and propose directions for future work. We showcase a process of co-manufacturing a custom spoon handle together with two people with cerebral palsy. Our digital manufacturing process was centered around videoconferencing to remotely control the processes from design to final 3D printing. Device functionality and satisfaction were assessed using standard clinical questionnaires: the Individual Priority Problem Assessment Questionnaire (IPPA) and the Quebec User Satisfaction Assessment with Assistive Technology (QUEST 2.0). IPPA was instrumental in assessing user needs and device effectiveness. QUEST revealed where to focus future design efforts. Involving people with disabilities in co-creation of assistive devices opens for new opportunities for healthcare providers that should be explored in depth using the described methodology. There may also be therapeutic benefits and we envisage specific actions to take in order to make it clinically viable. Best practices for co-creation of assistive devices, cost and benefits should be investigated and documented further. Standard questionnaires are useful for measuring effectiveness and satisfaction of co-created devices as well as for guiding design efforts. Co-creation may be a valuable element in therapeutic interventions as an opportunity to unfold creativity. [ABSTRACT FROM AUTHOR]

The esthetic rehabilitation of a patient is a demanding yet rewarding procedure, improving the form, function, and well-being of a patient. Three-dimensional (3D) printed, or additive manufactured, zirconia has recently entered the dental space, but without a thorough assessment or comparison. This pilot study utilized digital impressions of two demonstration casts: Cast 1 prepared both central incisors for full ceramic crown coverage, while cast 2 had a lateral incisor (#22) prepared for a ceramic veneer. Both casts underwent digital scanning (Straumann CARES 3, Straumann, Basel, Switzerland) to create virtual STL models. Cast 1 had two full zirconia anterior crowns digitally designed, and Cast 2 had a zirconia veneer digitally designed, using Exocad GmbH software by a certified dental technician at Schulich Dentistry. The STL files were used for fabricating six milled zirconia crowns for central incisor (#21) and six 3D-printed zirconia crowns for the other central incisor (#11). Similarly, for Cast 2, milled and 3D-printed zirconia veneers were made for the prepared lateral incisor (#22). Statistical analysis employed Minitab 16.1.0 software to construct a 2 × 2 table for cross-tabulation and chi-squared analysis. This statistical approach assessed the relationship between restoration design and processing method. Cochran–Mantel–Haenszel test evaluated categorical variables considering different classification variables. Milled restorations showed minor variations, while 3D-printed units displayed consistency. Statistical tests found no significant associations. This in vitro study suggests 3D-printed zirconia for crowns and veneers meets precementation standards akin to conventionally milled restorations. Further research can assess its potential benefits for dentistry's efficiency, cost, and sustainability. [ABSTRACT FROM AUTHOR]

Access to spare parts in the maritime industry is limited throughout most of a ship's life cycle. The limitation is caused by both the geographical distance of vessels from suppliers and the often limited turnaround time during which parts can be delivered. Manufacturing some parts onboard is possible, but it is a time-consuming and labour-intensive process. Advanced manufacturing techniques could be used to improve access to spare parts at sea by combining the desirable materials properties and flexibility of Direct Energy Deposition (DED) and the higher dimensional tolerances of Computer Numerical Control (CNC) manufacturing. The present study assesses the comparative viability of onboard implementation of advanced manufacturing techniques for offshore assets as a capital investment in different modes against an option of no onboard advanced manufacturing using a multi-criteria decision analysis method. To this end, a Technique to Order Preference by Similarity to Ideal Solution (TOPSIS) is employed considering the techno-economic and environmental aspects of the decision-making process as well as the inherent challenges that come with a new area of research. Finally, the challenges, opportunities, and pathways to onboard maintenance using additive manufacturing are discussed within the scope of the sustainable future for ship and offshore energy assets. [ABSTRACT FROM AUTHOR]

Digital light processing (DLP) techniques are widely employed in various engineering and design fields, particularly additive manufacturing. Acrylate resins utilized in DLP processes are well known for their versatility, which enables the production of defect-free 3D-printed products with excellent mechanical properties. This study aims to improve the mechanical and thermal properties of 3D-printed samples by incorporating mica as an inorganic filler at different concentrations (5%, 10%, and 15%) and optimizing the dispersion by adding a KH570 silane coupling agent. In this study, mica was introduced as a filler and combined with epoxy acrylate resin to fabricate a 3D-printed sample. Varying concentrations of mica (5%, 10%, and 15% w/w) were mixed with the epoxy acrylate resin at a concentration of 10%, demonstrating a tensile strength increase of 85% and a flexural strength increase of 132%. Additionally, thermal characteristics were analyzed using thermogravimetric analysis (TGA), and successful morphological investigations were conducted using scanning electron microscopy (SEM). Digital light-processing technology was selected for its printing accuracy and cost-effectiveness. The results encompass comprehensive studies of the mechanical, thermal, and morphological aspects that contribute to the advancement of additive manufacturing technology. [ABSTRACT FROM AUTHOR]

Advanced bioactive ceramic materials, Hydroxyapatite (HA) and Polylactic Acid (PLA) are common in bone regeneration implants. As demand for customised implant products increases, research increasingly focuses on developing composite filament manufacturing technology. However, creating PLA/HA composite filament faces challenges, including clumping HA particles and uneven flowability. The brittleness of the filament properties makes it unsuitable for Fused Deposition Modelling (FDM) printing, causing inconsistent extrusion and reduced filament strength. The purpose of this study is to compare the effectiveness of microHAs (m-HAs) and nanoHAs (n-HAs) in the production of filament composite fibers, based on the flowability assessment. The particle size of the micro-HA was reduced to nano by a ball mill process using 4 mL ethanol and the ball-powder ratio of 5:1, which was verified by the particle size analyzer. The feedstock comprises 79.5 wt.% PLA, 19.5 wt.% HA and 1 wt.% impact modifier (IMK) was mixed and rheological tested (130 °C to 150 °C, shear rate: 20-1000 s-1) to achieve pseudoplastic behaviour (n<1). The rheological tests showed that both feedstocks exhibited pseudoplastic behaviour (n<1) across all temperatures studied. The properties of the feedstock were observed by scanning electron microscopy (SEM), and tensile tests evaluated the filament strength. The investigation found that nanosized HA filament has 24% higher strength than micro-sized PLA/HA filament. [ABSTRACT FROM AUTHOR]

Neuroanatomy is widely regarded as one of the most complex subjects in veterinary education and clinical practice. Understanding the brain ventricles in particular can be quite challenging for learners. In addition to classical methods, three-dimensional (3D) printed models can provide an efficient learning process. This study aimed to assess the effectiveness of 3D-printed models (3DPM) depicting the dog brain ventricular system as educational tools in neurology and neuroanatomy. Additionally, it outlines the process of creating these models, from imaging specimens with a 3 Tesla magnetic resonance (MR) to 3D printing. MR imaging was performed on four mesocephalic dogs. The semi-automatic technique was performed on MR images to generate a 3D reconstruction of the brain ventricles. 3D digital images were used to create 3DPM with an FDM printer. An evaluation survey for learners was also conducted to evaluate the efficiency of 3DPM for neuroanatomy education. The ventricular system and associated anatomical structures were easily identified on MR images. A detailed 3D model of the ventricular system was created by this method. It was determined that 3DPM was easily handled, quickly reproducible, cost-efficient, and storable. Besides, a significant number of students stated that the use of 3DPM is necessary and will be more useful in learning neuroanatomy. This technique could help not only education partners like lecturers and learners but also clinicians like radiologists and surgeons to understand canine ventricular anatomy better. [ABSTRACT FROM AUTHOR]

This paper presents a systematic critical review of quantitative sustainability assessment studies on metal additive manufacturing (MAM) with a life cycle perspective. Potential benefits and present challenges of MAM are also discussed. MAM showed the potential to reduce overall environmental impacts and be more cost-effective for parts with complex designs, high value and low production volumes, particularly for automotive and aerospace components. However, currently, conventional manufacturing appears to have a better sustainability performance than MAM for simple parts in industrial applications. Overall, MAM technology is still in development, even if there have been optimizations and method consolidations. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the marginal adaptation and fracture resistance of three computer-aided design/computer-assisted manufacturing hybrid dental materials with different occlusal thicknesses. Methods: Ninety single-molar crowns were digitally fabricated using a milled hybrid nanoceramic (Cerasmart, CE), polymer-infiltrated ceramic network (PICN, Vita Enamic, VE), and 3D-printed materials (Varseosmile, VS) with occlusal thicknesses of 0.8, 1, and 1.5 mm (10 specimens/group). Anatomical 3D-printed resin dies (Rigid 10K) were used as supporting materials. A CEREC MCX milling unit and a DLP-based 3D printer, Freeform Pro 2, were utilized to produce the crown samples. Before cementation, the marginal adaptation, absolute marginal discrepancy (AMD), and marginal gap (MG) were assessed using micro-CT scanning. After cementation with self-adhesive resin cement, fracture resistance was evaluated using a universal testing machine. The number of fractured crowns and the maximum fracture values (N) were recorded. Data were statistically analyzed using both one- and two-way ANOVA, followed by Tukey's honestly significant difference (HSD) test. Results: For all occlusal thicknesses, the VS crowns demonstrated the lowest AMD and MG distances, significantly different from those of the other two milling groups (P < 0.05), whereas CE and VE did not differ significantly (P > 0.05). All VS crowns were fractured using the lowest loading forces (1480.3±226.1 to 1747.2±108.7 N). No CE and 1 and 1.5 mm VE crowns fractured under a 2000 N maximum load. Conclusions: All hybrid-material crowns demonstrated favorable marginal adaptation within a clinically acceptable range, with 3D printing yielding superior results to milling. All materials could withstand normal occlusal force even with a 0.8 mm occlusal thickness. [ABSTRACT FROM AUTHOR]

Additive manufacturing is a newly developed method that provides a compelling and practical alternative to conventional subtractive manufacturing methods. Therefore, this study evaluates and compares the color stability and microhardness of two types of 3D-printed definitive hybrid ceramic materials after storage in different staining solutions. A total of 180 rectangular shape samples were fabricated from Crowntec, VarseoSmile Crown Plus and Vita Enamic. 90 samples (14×12×1 mm) were stored in different staining solutions. The color measurements were taken at the baseline and after three different periods (one week, two weeks and one month) using an Easyshade advance 4.0 spectrophotometer. Another 90 samples (14×12×5 mm) were subjected to a one-week storage period. The Microhardness measurements were taken at the baseline and after a one-week staining period using a digital Vickers microhardness tester. Three-way ANOVA test at a 0.05 significance level followed by Tukey's for pairwise comparison among the groups. The CT had the highest color change (ΔE) compared to VS and VE. VE displayed the lowest ΔE value among different materials. Coffee caused a greater color change compared to tea and distilled water. In contrast, the lowest (ΔE) was observed in the distilled water. Regarding the microhardness test, the results showed a significant difference (P<0.05) between VE and 3D printed materials, with no significant difference between CT and VS. VE displayed the highest Microhardness value, while the lowest Microhardness was observed in VS material. 3D-printed hybrid materials seem to offer less color stability and lower microhardness when compared to CAD CAM material. [ABSTRACT FROM AUTHOR]

Background: Advancements in dentistry and incorporating 3D printing techniques have numerous benefits over traditional methods. However, the produced resins have shown a lack of good biocompatibility and insufficient mechanical properties. Tantalum oxide, on the other hand, exhibits biocompatibility, excellent physical and mechanical properties, and an antimicrobial effect. Aim of the study: To assess the tensile strength of tantalum oxide nanoparticles when used with 3D-printed denture-based resins before and after thermocycling. Materials and Methods: The materials tested in this study were laser-based stereolithography (an additive manufacturing process, SLA). Eighty samples were prepared from 3D-printed resin. The sample was divided into two groups (before and after thermocycling), and each group was subdivided into four subgroups. Results: There was a statistically significant association between the used concentrations when tested before and after thermocycling, with a high statistical significance (p-value = 0.001). Additionally, there was a high statistical significance for the concentration before thermocycling in relation to after thermocycling with (p-value 0.001). Conclusion: Using tantalum oxide improved the tensile strength of the 3D-printed resins by promoting characteristic osseointegration and enhancing its ability to promote osteoblast formation, proliferation, and integration into the bone. [ABSTRACT FROM AUTHOR]

3D‐printable vitrimers processed by digital light processing (DLP) have been recently developed, based on the transesterification reaction of β‐hydroxyester structures from mono‐ and diacrylate monomers employed in the formulation. These materials show promising repairability and recyclability, in addition to other interesting features such as shape memory and shape reconfigurability. It has been reported that structural changes taking place due to transesterification promote network rearrangement and an enhancement of the thermomechanical properties. However, the elevated temperatures required for the network reconfiguration cast some doubts on their applicability in real‐life scenarios. In this paper, we analyze the effect of the thermal treatment on the thermomechanical properties and relaxation behavior of these materials and discuss the underlying mechanism explaining the observed changes. We identify some critical issues related to use of a monoacrylate containing β‐hydroxyester moieties, and propose solutions to overcome the most relevant drawbacks. © 2023 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

This article describes the technology for manufacturing a metal composite structure of a metal-cutting tool body. The main problem with using metal 3D-printing is its prohibitively high cost. The initial data for carrying out finite element calculations are presented, in particular, the calculation and justification of the selected loads on the drill body arising from metal-cutting forces. The described methodology for designing a digital model of a metal-cutting tool for the purpose of its further production using SLM 3D metal printing methods facilitates the procurement of a digital model characterized by a reduced weight and volume of material. The described design technology involves the production of a thin-walled outer shell that forms the external technological surfaces necessary for the drill body, as well as internal structural elements formed as a result of topological optimization of the product shape. Much attention in this article is paid to the description of the technology for filling internal cavities with a viscous metal polymer, formed as a result of the topological optimization of the original model. Due to this design approach, it is possible to reduce the volume of 3D metal printing by 32%, which amounts to more than USD 135 in value terms. [ABSTRACT FROM AUTHOR]

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Background: The responsible use of 3D-printing in medicine includes a context-based quality assurance. Considerable literature has been published in this field, yet the quality of assessment varies widely. The limited discriminatory power of some assessment methods challenges the comparison of results. The total error for patient specific anatomical models comprises relevant partial errors of the production process: segmentation error (SegE), digital editing error (DEE), printing error (PrE). The present review provides an overview to improve the general understanding of the process specific errors, quantitative analysis, and standardized terminology. Methods: This review focuses on literature on quality assurance of patient-specific anatomical models in terms of geometric accuracy published before December 4th, 2022 (n = 139). In an attempt to organize the literature, the publications are assigned to comparable categories and the absolute values of the maximum mean deviation (AMMD) per publication are determined therein. Results: The three major examined types of original structures are teeth or jaw (n = 52), skull bones without jaw (n = 17) and heart with coronary arteries (n = 16). VPP (vat photopolymerization) is the most frequently employed basic 3D-printing technology (n = 112 experiments). The median values of AMMD (AMMD: The metric AMMD is defined as the largest linear deviation, based on an average value from at least two individual measurements.) are 0.8 mm for the SegE, 0.26 mm for the PrE and 0.825 mm for the total error. No average values are found for the DEE. Conclusion: The total error is not significantly higher than the partial errors which may compensate each other. Consequently SegE, DEE and PrE should be analyzed individually to describe the result quality as their sum according to rules of error propagation. Current methods for quality assurance of the segmentation are often either realistic and accurate or resource efficient. Future research should focus on implementing models for cost effective evaluations with high accuracy and realism. Our system of categorization may be enhancing the understanding of the overall process and a valuable contribution to the structural design and reporting of future experiments. It can be used to educate specialists for risk assessment and process validation within the additive manufacturing industry. Context of the figures in this review. Center: Fig. 5+ 7; top (blue): Fig. 8; right (green): Fig. 9; bottom (yellow): Fig. 10; left (red): Fig. 11. A version in high resolution can be found online in the supplementary material. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to determine and compare the biaxial flexural strength (BFS) and Vickers hardness (VHN) of additive and subtractive manufactured permanent composite-based restorative materials, before and after thermal aging. Methods: A total of 200 specimens were prepared; 100 disc-shaped specimens (diameter 13 × 1.2 mm) for the BFS test and 100 square specimens (14 × 14 × 2 mm) for the VHN test. The specimens were made from various materials: two subtractive composite-based blocks (Cerasmart 270 [CS], Vita Enamic [VE]), two additive composite-based resins used for two different vat polymerization methods (digital light processing [DLP]; Saremco Print Crowntec [SC] and stereolithography [SLA]; Formlabs Permanent Crown Resin [FP]), and one feldspathic glass-matrix ceramic block (Vita Mark II [VM]) as the control group. Specimens of each material were divided into two subgroups: thermal cycled or non-thermal cycled (n = 10). BFS and VHN tests were performed on all groups. Data were analyzed with two-way ANOVA and post hoc Tukey test (α = 0.05). Results: The type of restorative material used for the specimen had a statistically significant influence on both BFS and VHN values. However, thermal cycling did not affect the BFS and VHN values. After thermal cycling, the results of the BFS test were ranked from best to worst as follows: CS, FP, SC, VE, then VM. For the VHN values, the order from best to worst was as follows: VM, VE, CS, FP, then SC. Conclusions: 3D printed and milled composite groups showed higher BFS than feldspathic ceramics. When the VHN results were examined, it was seen that the 3D resin groups had the lowest VHN values. Furthermore, it was observed that the thermal cycle had no effect on BFS or VHN. [ABSTRACT FROM AUTHOR]

Simple Summary: Osteomyelitis is a bone infection disease causing progressive inflammation. Bone lysis, periosteal reactions and ischemic regions of infected necrotic and devitalized tissue are likely secondary abnormalities. A prolonged antibiotic therapy, an abundant lavage of the affected region and several revision surgeries to debride infected and necrotic bone are paramount treatments for osteomyelitis. The treatment of extensive bone defects and functional damage may require the use of prosthetic surgery, allowing the anatomical and functional recovery of the affected area, and in some cases, it is necessary to use a customized prosthesis for a better anatomical and functional adaptation. In veterinary medicine, the implementation of 3D-printing technologies and the application of custom-made surgical implants and prosthetics have enabled the management of intricate orthopedic conditions that were previously only addressed through salvage procedures, such as arthrodesis or amputations. The purpose of this report is to describe the surgical technique and outcome of a custom-made patellar groove replacement in a puppy with a severe bone defect in the femoral trochlea caused by hematogenous osteomyelitis. This surgery showed excellent short-, medium- and long-term outcomes, and it is the first report on a custom-made patellar groove replacement available in the literature. An 8-month-old male American Staffordshire terrier was referred for a no-weightbearing lameness of the right pelvic limb, hyperthermia, lethargy and inappetence. Two months before, endocarditis was diagnosed and treated in another veterinary hospital. Orthopedic, radiographic and tomographic examinations revealed a bone sequestrum of 4 × 1.4 cm and active periosteal reaction of the caudo-lateral cortical in the metaphysis and the distal third of the right femoral diaphysis, medullary osteolysis and interruption of the cranio-medial cortical profile, with involvement of the femoral trochlea leading to a secondary medial patella luxation. Hematogenous osteomyelitis was the suspected diagnosis. Once skeletally mature, after 4 months from surgical debridement and aggressive antibiotic therapy against Klebsiella oxytoca revealed by a bacteriological exam, the patient underwent prosthetic surgery for the application of a custom-made patellar groove replacement (PGR) to fill the bone defect and restore the femoral trochlea surface. Despite the serious injury that afflicted the right pelvic limb, the surgery had satisfactory outcomes until the last 18-month postoperative follow up. [ABSTRACT FROM AUTHOR]

Compressive mechanical properties of lattice structures made of titanium alloy Ti–6Al–4V, obtained using selective laser melting, are studied in three different metal conditions: in as-built SLM state, after chemical-heat treatment by ion nitriding, and after annealing. Specimen relative porosity is 50, 60, 70 and 80%. It is established that ion nitriding of lattice structures leads to formation upon them of antifriction layer surfaces several tens of micrometers thick. It is revealed that nitrogen saturation of surface layers for specimens with a degree of porosity of 50, 60, 70% does not have a significant effect on basic mechanical properties during compression, although it leads to an increase by more than 20% in surface hardness of beam elements. It is established that annealing at 720 °C leads to decomposition of the original martensitic α′-phase and to formation of a two-phase (α + β) structure, and removal of residual stresses. [ABSTRACT FROM AUTHOR]

The anodes based on the nickel oxide and yttria-stabilized zirconia are developed by the method of hybrid inkjet 3D-printing with laser treatment. The granulometric composition of the NiO/Zr0.9Y0.1O2-composite and the rheological characteristics of its based printing pastes are determined. The printing of three-dimensional test objects using the developed ceramic paste is studied experimentally. The influence of the pore formers—graphite and potato starch—added to the paste composition on the rheological characteristics of the paste is studied. The obtained samples of supporting anodes were studied by a complex of physicochemical methods to determine their morphological and structural characteristics. [ABSTRACT FROM AUTHOR]

A paste composition for inkjet 3D-printing based on the NiO–Ce0.8Gd0.2O2-composite is suggested and an anode billet for a solid-oxide fuel cell of planar geometry is developed using the direct inkjet 3D-printing. Effect of the printing mode and thermal annealing on the morphology and structure of the samples is studied. The anode billet is reduced and the resulting sample is characterized by a number of physicochemical methods. [ABSTRACT FROM AUTHOR]

To evaluate the effect of accelerated firing on 3D-printed zirconia. To check if formulae provided by ISO 6872 can be extended to thin samples, finite element analyses were carried out in advance of fabricating 3-mol% yttria-stabilized tetragonal zirconia polycrystal discs by milling and by 3D-printing. Four groups (n = 38 each) of 3D-printed specimens were produced with two nominal thicknesses (0.6 mm and 1.2 mm) and two firing strategies (long: 51 h, accelerated: 14.5 h). In the milled group (thickness 1.2 mm, n = 30), a standard firing program (9.8 h) was selected. Biaxial flexural strength tests were applied and mean strength, characteristic strength, and Weibull modulus were calculated for each group. Differences were analyzed using Welch ANOVA and Dunnett-T3 post-hoc tests. Maximum tensile stresses occurring during biaxial strength testing can be calculated according to ISO 6872 for thin samples with b > 0.3 mm. Variability of measured strengths values was smaller for milled zirconia compared with 3D-printed zirconia. The 1.2-mm-thick 3D-printed samples had significantly decreased strength after accelerated firing than after long firing. However, for the 0.6-mm-thick samples, comparable mean biaxial strength values of about 1000 MPa were measured for both firing protocols. At the moment, long fabrication time for zirconia restorations is a major drawback of 3D-printing when compared with milling technology. This investigation showed that the strength of 0.6-mm-thick zirconia discs fabricated by 3D-printing was not impaired by accelerated firing. Thus, overnight firing of thin-walled 3D-printed zirconia restorations could be possible. • For thin disks (b=0.6 mm), both firing times led to high mean strengths (≈1000 MPa). • Lowest mean strength (805 MPa) was given for fast fired thick samples (b=1.2 mm). • About half of the fast-fired thick samples (b=1.2 mm) had strength values < 500 MPa. • Milled zirconia was more reliable than 3D-printed zirconia. • ISO 6872 formulae can be extended to samples with thicknesses 0.3 mm

This comprehensive review explores recent advancements in immobilization strategies for graphitic carbon nitride (g-C3N4), a metal-free photocatalyst that has gained significant attention for its optical and physicochemical properties comparable to traditional photocatalysts like TiO2. However, a critical challenge regarding their application has emerged from the difficulty of its recovery due to its powdery nature. Therefore, several alternatives are being explored to immobilize this material, facilitating its recovery and reuse. This review systematically categorizes various physical and chemical immobilization techniques, providing an in-depth analysis of their advantages, drawbacks, and applications. Techniques such as encapsulation, electrospinning, casting, and coating, along with their adaptations for g-C3N4, are thoroughly examined. Additionally, the impact of these strategies on enhancing the photocatalytic efficiency and operational stability of g-C3N4, particularly in environmental applications, is also assessed. Thus, this review aims to provide valuable insights and guide future research in the realms of photocatalysis and environmental remediation. The review contributes to the understanding of how immobilization strategies can optimize the performance of g-C3N4, furthering its potential applications in sustainable and efficient environmental solutions. [ABSTRACT FROM AUTHOR]

Assistive devices are designed to enhance individuals with disabilities' functional abilities. The rise of 3D printing technology enabled the production of individualized assistive devices (IADs). A REHAB-LAB is intended for IAD provision involving technical referents and occupational therapists. This study aimed to develop the REHAB-LAB logic model; to explore its fidelity and desirability; and to explore the characteristics of arising initiatives of IAD production. The REHAB-LAB logic model development involved stakeholders throughout the research process. A pragmatic multimethod approach followed two phases 1) logic model development and 2) exploration of its fidelity and desirability. The REHAB-LAB logic model presented the resources (equipment, space, human) required to implement IAD provision in a rehabilitation center, and the expected deliverables (activities and outputs). The REHAB-LAB logic model highlights the interdisciplinarity of IAD provision including occupational therapists, doctors, engineers, managers, and technical referents and places the users at the center of the IAD production. Results confirmed the fidelity and desirability of the REHAB-LAB logic model. The REHAB-LAB logic model can be used as a reference for future healthcare organizations wishing to implement an IAD provision. This research highlighted the interest of IAD provision based on the REHAB-LAB model involving users and transdisciplinary practices [ABSTRACT FROM AUTHOR]

Three-dimensional printing (3DP) technology has revolutionized the field of the use of bioceramics for maxillofacial and periodontal applications, offering unprecedented control over the shape, size, and structure of bioceramic implants. In addition, bioceramics have become attractive materials for these applications due to their biocompatibility, biostability, and favorable mechanical properties. However, despite their advantages, bioceramic implants are still associated with inferior biological performance issues after implantation, such as slow osseointegration, inadequate tissue response, and an increased risk of implant failure. To address these challenges, researchers have been developing strategies to improve the biological performance of 3D-printed bioceramic implants. The purpose of this review is to provide an overview of 3DP techniques and strategies for bioceramic materials designed for bone regeneration. The review also addresses the use and incorporation of active biomolecules in 3D-printed bioceramic constructs to stimulate bone regeneration. By controlling the surface roughness and chemical composition of the implant, the construct can be tailored to promote osseointegration and reduce the risk of adverse tissue reactions. Additionally, growth factors, such as bone morphogenic proteins (rhBMP-2) and pharmacologic agent (dipyridamole), can be incorporated to promote the growth of new bone tissue. Incorporating porosity into bioceramic constructs can improve bone tissue formation and the overall biological response of the implant. As such, employing surface modification, combining with other materials, and incorporating the 3DP workflow can lead to better patient healing outcomes. [ABSTRACT FROM AUTHOR]

We compared patient satisfaction and clinical effectiveness of 3D-printed splints made of photopolymer resin to conventional fibre glass casts in treating distal radial fractures. A total of 39 patients with minimally displaced distal radius fractures were included and randomized. Of them, 20 were immobilized in a fibre glass cast and 19 in a 3D-printed forearm splint. The 3D-printed splints were custom-designed based on forearm surface scanning with a handheld device and printed in-house using digital light processing printing technology. Patient satisfaction and clinical effectiveness were assessed with questionnaires 1 and 6 weeks after the initiation of immobilization. Fracture healing, pain, range of motion, grip strength and the DASH and PRWE scores were assessed up to 1-year follow-up. 3D-printed splints proved to be equally well tolerated by the patients and equally clinically effective as conventional fibre glass casts although there was a higher rate of minor complications. 3D-printed splints present a safe alternative, especially in young, active patients, for non-operative treatment of distal radial fractures. Level of evidence: I [ABSTRACT FROM AUTHOR]

Continuous chromatography has emerged as one of the most attractive methods for protein purification. Establishing such systems involves installing several chromatographic units in series to enable continuous separation processes and reduce the cost of the production of expensive proteins and biopharmaceuticals (such as monoclonal antibodies). However, most of the established systems are bulky and plagued by high dead volume, which requires further optimization for improved separation procedures. In this article, we present a miniaturized periodic counter-current chromatography (PCCC) system, which is characterized by substantially reduced dead volume when compared to traditional chromatography setups. The PCCC device was fabricated by 3D printing, allowing for flexible design adjustments and rapid prototyping, and has great potential to be used for the screening of optimized chromatography conditions and protocols. The functionality of the 3D-printed device was demonstrated with respect to the capture and polishing steps during a monoclonal antibody purification process. Furthermore, this novel miniaturized system was successfully used for two different chromatography techniques (affinity and ion-exchange chromatography) and two different types of chromatographic units (columns and membrane adsorbers). This demonstrated versability underscores the flexibility of this kind of system and its potential for utilization in various chromatography applications, such as direct product capture from perfusion cell cultures. [ABSTRACT FROM AUTHOR]

Purpose: A well-known limitation of multi-leaf collimators is that they cannot easily form island blocks. This can be important in mantle region therapy. Cerrobend photon blocks,currently used for supplementary shielding,are laborintensive and error-prone.To address this,an innovative,non-toxic,automatically manufactured photon block using 3D-printing technology is proposed, offering a patient-specific and accurate alternative. Methods and materials: The study investigates the development of patientspecific photon shielding blocks using 3D-printing for three different patient cases. A 3D-printed photon block shell filled with tungsten ball bearings (BBs) was designed to have similar dosimetric properties to Cerrobend standards. The generation of the blocks was automated using the Eclipse Scripting API and Python. Quality assurance was performed by comparing the expected and actual weight of the tungsten BBs used for shielding.Dosimetric and field geometry comparisons were conducted between 3D-printed and Cerrobend blocks, utilizing ionization chambers, imaging, and field geometry analysis. Results: The quality assurance assessment revealed a -1.3% average difference in the mass of tungsten ball bearings for different patients. Relative dose output measurements for three patient-specific blocks in the blocked region agreed within 2% of each other. Against the Treatment Planning System (TPS), both 3D-printed and Cerrobend blocks agreed within 2%. For each patient,6 MV image profiles taken through the 3D-printed and Cerrobend blocks agreed within 1% outside high gradient regions.Jaccard distance analysis of the MV images against the TPS planned images, found Cerrobend blocks to have 15.7% dissimilarity to the TPS,while that of the 3D-printed blocks was 6.7%. Conclusions: This study validates a novel,efficient 3D-printing method for photon block creation in clinical settings. Despite potential limitations, the benefits include reduced manual labor, automated processes, and greater precision. It holds potential for widespread adoption in radiation therapy, furthering non-toxic radiation shielding. [ABSTRACT FROM AUTHOR]

Abstract Modern human societies are highly dependent on plastic materials, however, the bulk of them are non‐renewable commodity plastics that cause pollution problems and consume large amounts of energy for their thermal processing activities. In this article, a sustainable cellulose hydroplastic material and its composites, that can be shaped repeatedly into various 2D/3D geometries using just water are introduced. In the wet state, their high flexibility and ductility make it conducive for the shaping to take place. In the ambient environment, the wet hydroplastic transits spontaneously into rigid materials with its intended shape in a short time of

Three-dimensional (3D) bioprinting technology allows the production of porous structures with complex and varied geometries, which facilitates the development of equally dispersed cells and the orderly release of signal components. This is in contrast to the traditional methods used to produce tissue scaffolding. To date, 3D bioprinting has employed a range of cell-laden materials, including organic and synthetic polymers, to construct scaffolding systems and manufacture extracellular matrix (ECM). Still, there are several challenges in meeting the technical issues in bio-ink formulations, such as the printability of bio-inks, the customization of mechanical and biological properties in bio-implants, the guidance of cell activities in biomaterials, etc. The main objective of this article is to discuss the various strategies for preparing bio-inks to mimic native tissue's extracellular matrix environment. A discussion has also been conducted about the process parameters of bio-ink formulations and printing, structure requirements, and fabrication methods of durable bio-scaffolds. The present study also reviews various 3D-printing techniques. Conclusively, the challenges and potential paths for smart bioink/scaffolds have been outlined for tissue regeneration.

Reactive oxygen species play a vital role in tissue repair, and nonequilibrium of redox homeostasis around bone defect can compromise osteogenesis. However, insufficient antioxidant capacity and weak osteogenic performance remain major obstacles for bone scaffold materials. Herein, integrating the mussel-inspired polydopamine (PDA) coating and 3D printing technologies, we utilized the merits of both osteogenic bredigite and antioxidative fullerol to construct 3D-printed porous, biodegradable acid-buffering, reactive oxygen species (ROS) -scavenging and robust osteogenic bio-scaffold (denoted “FPBS”) for in situ bone defect restoration under oxidative stress microenvironment. Initially, fullerol nanoparticles were attached to the surface of the bredigite scaffold via covalently inter-crosslinking with PDA. Upon injury, extracellular ROS capturing triggered the oxidative degradation of PDA, releasing fullerol nanoparticles to enter into cells for further intracellular ROS scavenging. In vitro, FPBS had good biocompatibility and excellent antioxidative capability. Furthermore, FPBS promoted the osteogenesis of stem cells with significant elevation of osteogenic markers. Finally, in vivo implantation of FPBS remarkably enhanced new bone formation in a rat critical calvarial defect model. Overall, with amelioration of the ROS microenvironment of injured tissue and enhancement of osteogenic differentiation of stem cells simultaneously, FPBS may hold great potential towards bone defect repair.

Composite materials fabricated via additive manufacturing are becoming more relevant in ready-for use products used in engineering applications like aerospace structures, propellers, electric vehicles, or sandwich cores. Continuous Fiber Reinforced Polymeric (CFRP) composites are 3D-printed composites with tailor-made properties due to the capability of the printing process to deposit matrix and fiber whenever required. However, CFRP products behave differently and have lower mechanical properties than traditional composites. This study aimed to analyze the impact strength of CFRP specimens with gyroid infill and the effects of two build (flat and on-edge) and two raster (0° and 45°) orientations on impact behavior. The gyroid infill helps to obtain a light-weight structure and it has been used in energy absorption applications showing excellent mechanical behavior in thermoplastic 3D-products. The specimens were manufactured using Onyx as the matrix and aramid fiber as the reinforcement materials. The impact energy absorption of CFRP composites was measured using unnotched Izod impact specimens. The impact tests results were statistically analyzed, revealing that the build orientation directly and significantly affects the impact behavior, resulting in higher impact absorption when flat orientation is used to produce CFRP composites. The impact strength of CFRP composites increased 8 times, and 2 times for flat and on-edge oriented specimens, respectively compared to pure Onyx specimens. The variation in impact energy absorption between raster orientations in both build orientations was not significant, the difference in flat-oriented specimens at 0° and 45° was only 0.2 J, and between on-edge-oriented specimens at 0° and 45° was only 0.089 J. Also, the after impact specimens were analyzed to categorize the different failure modes observed. The after-impact analysis showed poor impregnation between aramid and onyx layers, causing delamination, fiber bridging, and fiber exposure failures. The combination of Aramid, Onyx, and a non-solid infill (gyroid) demonstrated positive results in impact behavior, obtaining high-impact absorption (165 kJ/m2) with no more than 56 % of fiver volume. The impact properties information of CFRP composites made with aramid fibers is still very scarce, joined to the lack of information on the impact properties of CFRP composites with non-solid infill, like gyroids or sinusoidal path infills. The results of this research open the possibility of using non-solid infill in CFR process that can be used to manufacture and test ready-for-use CFRP products in tasks that require high-strength, low-weight structures and impact energy absorption.

Additive manufactured (AM) 94 % alumina was successfully 3D printed using the Lithography Ceramic Manufacturing (LCM) technique. Each 3D printed sample was exposed to a different stage of the thermal post-process to identify changes in chemical composition at each stage. The thermal phases studied were the as printed green state, preconditioning at 120 °C, debinding at 600 °C, debinding at 1100 °C, and sintering at 1650 °C. Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Thermogravimetric Analysis (TGA), and X-Ray Fluorescence (XRF) were used to evaluate the changes in composition at each stage of the thermal post-process. Cross-sectional images of 3D printed alumina samples after thermal exposure were captured using scanning electron microscopy (SEM).

IntroductionIntervertebral disk degeneration is a growing problem in our society. The degeneration of the intervertebral disk leads to back pain and in some cases to a herniated disk. Advanced disk degeneration can be treated surgically with either a vertebral body fusion or a disk prosthesis. Vertebral body fusion is currently considered the gold standard of surgical therapy and is clearly superior to disk prosthesis based on the number of cases. The aim of this work was the 3D printing of Gyroid structures and the determination of their mechanical properties in a biomechanical feasibility study for possible use as an intervertebral disc prosthesis.Material and methodsCreo Parametric 6.0.6.0 was used to create models with various Gyroid properties. These were printed with the Original Prusa i3 MK3s+. Different flexible filaments (TPU FlexHard and TPU FlexMed, extrudr, Lauterach, Austria) were used to investigate the effects of the filament on the printing results and mechanical properties of the models. Characterization was carried out by means of microscopy and tension/compression testing on the universal testing machine.ResultsThe 3D prints with the FlexHard and FlexMid filament went without any problems. No printing errors were detected in the microscopy. The mechanical confined compression test resulted in force-deformation curves of the individual printed models. This showed that changing the Gyroid properties (increasing the wall thickness or density of the Gyroid) leads to changes in the force-deformation curves and thus to the mechanical properties.ConlcusionThe flexible filaments used in this work showed good print quality after the printing parameters were adjusted. The mechanical properties of the discs were also promising. The parameters Gyroid volume, wall thickness of the Gyroid and the outer wall played a decisive role for both FlexMed and FlexHard. All in all, the Gyroid structured discs (Ø 50 mm) made of TPU represent a promising approach with regard to intervertebral disc replacement. We would like to continue to pursue this approach in the future.

BackgroundCervical spinal fusion surgeries require accurate placement of the pedicle screws. Any misplacement/misalignment of these screws may lead to injuries to the spinal cord, arteries and other organs. Template guides have emerged as accurate and cost-effective tools for the safe and rapid insertions of pedicle screws.Questions/PurposesNovel patient-specific single- and multi-level non-covering templates for cervical pedicle screw insertions were designed, 3D-printed, and evaluated.MethodsCT scans of two patients were acquired to reconstruct their 3D spine model. Two sets of single-level (C3-C7) and multi-level (C4-C6) templates were designed and 3D-printed. Pedicle screws were inserted into the 3D-printed vertebrae by free-hand and guided techniques. For single-level templates, a total of 40 screws (2 patients × 5 vertebrae × 2 methods × 2 screws) and for multi-level templates 24 screws (2 patients × 3 vertebrae × 2 methods × 2 screws) were inserted by an experienced surgeon. Postoperative CT images were acquired to measure the errors of the entry point, 3D angle, as well as axial and sagittal plane angles of the inserted screws as compared to the initial pre-surgery designs. Accuracy of free-hand and guided screw insertions, as well as those of the single- and multi-level guides, were also compared using paired t-tests.ResultsDespite the minimal removal of soft tissues, the 3D-printed templates had acceptable stability on the vertebrae during drillings and their utilization led to statistically significant reductions in all error variables. The mean error of entry point decreased from 3.02 mm (free-hand) to 0.29 mm (guided) using the single-level templates and from 5.7 mm to 0.76 mm using the multi-level templates. The percentage reduction in mean of other error variables for, respectively, single- and multi-level templates were as follows: axial plane angle: 72% and 87%, sagittal plane angle: 56% and 78%, and 3D angle: 67% and 83%. The error variables for the multi-level templates generally exceeded those of the single-level templates. The use of single- and multi-level templates also considerably reduced the duration of pedicle screw placements.ConclusionThe novel single- and multi-level non-covering templates are valuable tools for the accurate placement of cervical pedicle screws.

Educational robots offer a platform for training aspiring engineers and building trust in technology that is envisioned to shape how we work and live. In education, accessibility and modularity are significant in the choice of such a technological platform. In order to foster continuous development of the robots as well as to improve student engagement in the design and fabrication process, safe production methods with low accessibility barriers should be chosen. In this paper, we present Robotont 3, an open-source mobile robot that leverages Fused Deposition Modeling (FDM) 3D-printing for manufacturing the chassis and a single dedicated system board that can be ordered from online printed circuit board (PCB) assembly services. To promote accessibility, the project follows open hardware practices, such as design transparency, permissive licensing, accessibility in manufacturing methods, and comprehensive documentation. Semantic Versioning was incorporated to improve maintainability in development. Compared to the earlier versions, Robotont 3 maintains all the technical capabilities, while featuring an improved hardware setup to enhance the ease of fabrication and assembly, and modularity. The improvements increase the accessibility, scalability and flexibility of the platform in an educational setting.

In 3D-printing, sodium silicate (SS) can be used as an inorganic binder for wood-based composites due to its better rheological properties, high strength, and affordability. Investigating the recyclability of 3D-printed composites is necessary to understand the reusability of demolished additively manufactured construction waste. In this work, the bio-oil through pyrolysis was produced using pine and SS composites and further characterized to observe the effects of the pyrolysis temperatures and the proportion of SS in composites. Pine and SS composites with 0, 33.33, 50, and 66.67 % of the SS on a mass basis were prepared and cured to mimic the 3D-printed composites. Then, pyrolysis of cured composites was performed in a bench-scale fixed bed pyrolysis reactor at four temperatures (450–600 °C). From the pyrolysis of composites with 66 % SS at 600 ℃, a maximum condensed liquid yield of 68 % (wt.%, dry basis) was obtained. Further, it was observed that the selectivity towards hydrocarbons and alkyl phenols increased by increasing the proportion of SS in the composite, but methoxy phenols decreased, which enhanced bio-fuel production. A maximum hydroxyl concentration of 6.54 mmol g−1 was observed for the bio-oil from pyrolysis of SS-based composite at 600 ℃. This study shows the feasibility of upcycling the 3D-printed wood composites through pyrolysis to generate bio-oil that can be used for bio-based resin synthesis and bio-fuel applications.