Additive manufacturing (AM) has gained significant traction in the production of high-performance metallic components, yet concerns persist regarding the consistency of powder materials and the mechanical properties of 3D-printed parts. This study addresses these challenges through a detailed analysis of a maraging steel part manufactured using laser powder bed fusion. The demonstration part was evaluated for geometric accuracy, surface roughness, chemical composition, microstructure, and mechanical properties, including hardness and density. The findings revealed that 3D-printed maraging steel components can achieve high levels of dimensional precision and mechanical integrity, making them suitable for demanding applications. Despite these promising results, the study highlighted the need for improved powder quality control and accurate composition measurement to ensure the consistent production of reliable parts. The non-destructive hardness testing method applied in this study proved effective for predicting tensile strength, offering a streamlined approach to quality assurance. These results contribute to a growing body of research and knowledge supporting the adoption of AM for producing critical mechanical components, while underscoring the need for further investigation into quality assurance and standardized non-destructive testing procedures for high-performance metal AM parts.

Mandibular reconstruction remains a significant clinical challenge due to irregular defect geometries, high functional restoration requirements, and complex oral environments. Traditional vascularized bone grafts, while effective, are limited by donor site complications and poor osseointegration. Hydrogel-based materials have emerged as promising alternatives due to their biocompatibility, tunable mechanical properties, and capacity to mimic the extracellular matrix for osteogenesis and angiogenesis. This review highlights recent advances in hydrogel design strategies tailored for mandibular regeneration. Key considerations include mechanical reinforcement through nanocomposites and dual-network architectures, which enhance compressive strength and toughness to withstand masticatory loads. Injectable hydrogels demonstrate minimally invasive delivery and shape adaptability for irregular defects, while biomimetic wet adhesives achieve robust tissue integration through covalent and coordination bonding mechanisms. Functionalization with bioactive factors and stem cells promotes spatiotemporal regulation of osteogenesis and angiogenesis, as evidenced by successful mandibular regeneration in preclinical models. Antibacterial strategies integrating metal ions, antibacterial agents, or peptides can contribute to addressing oral microbial challenges. This review underscores the potential of multifunctional hydrogels to bridge structural and functional regeneration in craniofacial reconstruction while identifying critical research gaps for future innovation.

Part density and part porosity are important parameters for additively manufactured (AM) components, as they significantly influence mechanical properties and indicate printing process’s quality. Various measurement methods are available such as gas pycnometry, gravimetric density measurements (Archimedes’ principle), and micrograph analyses. This study compared these methods by analyzing test specimens made from different materials using diverse AM processes. AM components made of metal, ceramic, and plastic as well as composites were analyzed with regard to part density and porosity. The results provided new findings on part density and porosity in AM processes and materials. Furthermore, they demonstrated the suitability of the employed measurement methods for certain purposes. In this context, it is always important to distinguish between the determination of true and apparent density. Gas pycnometry is best suited for determining the true density and enables the most accurate density measurement. Gravimetric measurement according to Archimedes’ principle is generally best suited for determining the apparent density, which is more relevant for characterizing the technical properties of AM components. Micrograph analyses are the only investigated method that shows the position of the pores in the component. However, the method generally only allows statements to be made in the sectional plane under consideration. In addition, gas pycnometry is preferable for very dense AM components and the Archimedes method for porous parts. Finally, the results can be generalized and recommendations for measuring porosity and density can be concluded for other AM processes.

For high-carbon steels that are particularly sensitive to thermally induced phase transformations, the rapid solidification rates inherent to laser powder bed fusion (LPBF) offer a promising pathway to develop unconventional microstructures directly in the as-printed state. This study demonstrates the formation of a supersaturated austenitic matrix - engineered through carbon meta-stabilization and rapid solidification for subsequent heat treatments to develop complex, hierarchical microstructural constituents. A predominantly austenitic high-carbon steel, decorated with cellular segregation networks, was successfully fabricated using LPBF. Post-processing through cryogenic quenching and high-temperature solutionizing treatment, followed by low-temperature tempering, yielded a wide range of microstructures and hardness values. The cryogenically quenched sample exhibited a mixed microstructure of martensite, retained austenite, and cellularly segregated regions, achieving a hardness of 737 ± 31 HV. In contrast, the combination of solutionizing, cryogenic quenching, and tempering produced a multiphase matrix consisting of martensite, bainite, and austenite, with a hardness of 700 ± 20 HV. The insights gained into phase transformations and microstructural evolution during LPBF, along with secondary hardening via heat treatment, provide a foundation for developing tailored post-processing strategies for a broad class of hardenable steels produced by additive manufacturing.

Binder jetting (BJT) has been extensively explored for additive manufacturing of ceramics due to its ability to create complex structures by processing refractory and hard-to-machine materials. However, achieving a uniform powder bed with high packing density while processing ceramics in BJT remains a challenge. This study systematically examines the role of powder size, powder temperature, flow behavior, and powder size distribution on powder bed formation and resulting part properties. Four different alumina powder sizes (1 μm, 5 μm, 10 μm, and 20 μm) were investigated. Flowability characterizations reveal that 1 μm powder remains poorly flowable at both room and elevated temperatures, while 20 μm powder demonstrates excellent flowability at both temperatures. Smaller powders, especially 1 μm, exhibit around 25% loss in moisture, which results in pronounced agglomeration at room temperature. Discrete element method simulations were used to identify the ideal mixing ratio of the bimodal powder using 5 μm and 20 μm powders. For bimodal powder, both the simulation and the experiments exhibited a preferential deposition of smaller powders in the spreading direction. However, the 5 μm and 20 μm powders did not show any preferential deposition in the simulation, but experiments showed preferential deposition behavior. When using bimodal powder, packing density decreases by 7.65% along the spreading direction, which aligns with an 8.19% drop in part relative density. These findings offer valuable insights into the effects of bimodal powder distribution for controlling powder bed packing density and potentially leveraging spatial density variations for functional applications such as biomedical implants, heat exchangers, and gas filtration.

Mouthguards are orthodontic devices designed to prevent orofacial injuries during sports activities. To ensure comfort and correct positioning, they must fit the athlete’s dental arch precisely. Customization through additive manufacturing offers a practical solution for producing well-fitted mouthguards. The present study aimed to investigate the use of 3D-printed multi-material parts in the fabrication of protective mouthguards. Three polymeric materials were employed: High-impact polystyrene (HIPS), thermoplastic polyurethane, and poly(methyl methacrylate) (PMMA). Two configurations - bi-layered and tri-layered - were analyzed to assess the influence of material arrangement on mechanical performance. The impact of disinfection methods on mechanical properties was also evaluated, comparing physical (ultraviolet [UV]-C light exposure) and chemical (Polident cleaning tablet solution) disinfection strategies. In addition, the effects of artificial saliva aging on all material types and configurations were examined. Mechanical testing revealed that multi-material configurations containing HIPS exhibited superior mechanical performance, with flexural stiffness values 8 - 40% higher than PMMA-based samples, Vickers microhardness 40 - 128% greater, and absorbed energy and impact strength improved by 11 - 105%. Moreover, the tri-layered configuration demonstrated enhanced mechanical behavior, showing approximately 40% higher transverse impact resistance and increases of ~35% and ~77% in flexural strength and modulus, respectively, relative to the bi-layered configuration. Disinfection studies confirmed the efficacy of both approaches, reducing Staphylococcus aureus colony-forming units by 95% (Polident) and 97% (UVC light). These findings are promising for the development of protective mouthguards, where changes in mechanical properties over time - particularly due to saliva exposure and disinfection - are of critical importance.

Porous structures offer lightweight design and geometric flexibility for applications in transportation and bioengineering. Additive manufacturing, particularly laser powder bed fusion (LPBF), enables the fabrication of complex porous architectures. However, achieving an optimal balance between weight reduction and mechanical performance remains challenging. Therefore, further investigation into the design of porous structures is essential. This study explores the dynamic mechanical behavior of porous AlSi10Mg structures designed using a parametric modeling approach and the Voronoi tessellation algorithm. The structures, fabricated via LPBF, feature varying single-unit cell rotation angles and porosities. The dynamic mechanical behaviors were experimentally investigated under different impact energies to assess the influence of single-unit cell rotation on impact properties, complemented by finite element analysis simulations. The results indicate that a slight decrease in porosity by 10% (from 90% to 80%) significantly enhances energy absorption and impact resistance while maintaining lightweight features. Significant variations are observed in peak contact force and energy absorption trends. The results demonstrate that single-unit cell rotation improves impact resistance in certain cases, leading to significant enhancements in energy absorption, specific energy absorption, and specific strength, which increased by approximately 18.9% (P90), 17.1% (P90), and 79.5% (P80), respectively, for the dodecahedral (Dodeca)-C structure compared to the original Dodeca-A counterpart at impact of 124 J. In addition, Dodeca-C P80 showed a remarkable 73.1% increase in energy absorption compared to Dodeca-A P80 at a higher impact energy of 248 J. This study provides insights for optimizing porous structures while maintaining consistent unit cell configurations and identical porosity, with rotating unit cell angles enhancing impact resistance.

Biomedical materials have become essential for diagnosing, treating, and repairing diseased tissues, with applications ranging from hard dental implants to soft artificial blood vessels. Among these, fibrous silk (FS) - a naturally assembled material with exceptional mechanical and biological properties - has recently emerged as a promising candidate for advancing biomedical technologies, particularly with the advent of additive manufacturing and three-dimensional (3D) printing. This review comprehensively explores the advancements in FS-based materials for biomedical applications over the past two decades (2004 - 2024). FS, a unique material derived from silkworm silk fibers, exhibits exceptional mechanical properties, biocompatibility, controlled biodegradability, and antimicrobial characteristics, positioning it as a versatile candidate for various biomedical applications. The review begins with a detailed analysis of FS structure and morphology, covering natural FS, derived FS, and assembled FS. It then delves into the critical properties relevant to biomedical applications, such as mechanical resilience, biointegration, controlled degradation profiles, and antimicrobial performance. Subsequently, the review examines the extensive applications of FS-based materials across various biomedical fields, particularly in tissue engineering and regenerative medicine. Special emphasis is placed on the role of additive manufacturing and 3D printing in enhancing the design complexity and functional performance of FS-based scaffolds, highlighting their potential for developing customized implants and tissue-engineered constructs. Finally, the review provides insights into the future potential of FS-based materials, addressing current limitations and proposing strategies to further optimize their functionality in biomedical contexts.