3D Printing of Bioinert Oxide Ceramics for Medical Applications

Three-dimensionally printed metals and polymers have been widely used and studied in medical applications, yet ceramics also require attention. Ceramics are versatile materials thanks to their excellent properties including high mechanical properties and hardness, good thermal and chemical behavior, and appropriate, electrical, and magnetic properties, as well as good biocompati- bility. Manufacturing complex ceramic structures employing conventional methods, such as ceramic injection molding, die pressing or machining is extremely challenging. Thus, 3D printing breaks in as an appropriate solution for complex shapes. Amongst the different ceramics, bioinert ceramics appear to be promising because of their physical properties, which, for example, are similar to those of a replaced tissue, with minimal toxic response. In this way, this review focuses on the different medical applications that can be achieved by 3D printing of bioinert ceramics, as well as on the latest advances in the 3D printing of bioinert ceramics. Moreover, an in-depth comparison of the different AM technologies used in ceramics is presented to help choose the appropriate methods depending on the part geometry.Peer ReviewedPostprint (published version

Development of AM technologies for metals in the sector of medical implants

Additive manufacturing (AM) processes have undergone significant progress in recent years, having been implemented in sectors as diverse as automotive, aerospace, electrical component manufacturing, etc. In the medical sector, different devices are printed, such as implants, surgical guides, scaffolds, tissue engineering, etc. Although nowadays some implants are made of plastics or ceramics, metals have been traditionally employed in their manufacture. However, metallic implants obtained by traditional methods such as machining have the drawbacks that they are manufactured in standard sizes, and that it is difficult to obtain porous structures that favor fixation of the prostheses by means of osseointegration. The present paper presents an overview of the use of AM technologies to manufacture metallic implants. First, the different technologies used for metals are presented, focusing on the main advantages and drawbacks of each one of them. Considered technologies are binder jetting (BJ), selective laser melting (SLM), electron beam melting (EBM), direct energy deposition (DED), and material extrusion by fused filament fabrication (FFF) with metal filled polymers. Then, different metals used in the medical sector are listed, and their properties are summarized, with the focus on Ti and CoCr alloys. They are divided into two groups, namely ferrous and non-ferrous alloys. Finally, the state-of-art about the manufacture of metallic implants with AM technologies is summarized. The present paper will help to explain the latest progress in the application of AM processes to the manufacture of implantsPostprint (published version

3D printing in medicine for preoperative surgical planning: a review

The aim of this paper is to review the recent evolution of additive manufacturing (AM) within the medical field of preoperative surgical planning. The discussion begins with an overview of the different techniques, pointing out their advantages and disadvantages as well as an in-depth comparison of different characteristics of the printed parts. Then, the state-of-the-art with respect to preoperative surgical planning is presented. On the one hand, different surgical planning prototypes manufactured by several AM technologies are described. On the other hand, materials used for mimicking different living tissues are explored by focusing on the material properties: elastic modulus, hardness, etc. As a result, doctors can practice before performing surgery and thereby reduce the time needed for the operation. The subject of patient education is also introduced. A thorough review of the process that is required to obtain 3D printed surgical planning prototypes, which is based on different stages, is then carried out. Finally, the ethical issues associated with 3D printing in medicine are discussed, along with its future perspectives. Overall, this is important for improving the outcome of the surgery, since doctors will be able to visualize the affected organs and even to practice surgery before performing it.Postprint (author's final draft

Characterization of 3D Printed Metal-PLA Composite Scaffolds for Biomedical Applications

Three-dimensional printing is revolutionizing the development of scaffolds due to their rapid-prototyping characteristics. One of the most used techniques is fused filament fabrication (FFF), which is fast and compatible with a wide range of polymers, such as PolyLactic Acid (PLA). Mechanical properties of the 3D printed polymeric scaffolds are often weak for certain applications. A potential solution is the development of composite materials. In the present work, metal-PLA composites have been tested as a material for 3D printing scaffolds. Three different materials were tested: copper-filled PLA, bronze-filled PLA, and steel-filled PLA. Disk-shaped samples were printed with linear infill patterns and line spacing of 0.6, 0.7, and 0.8 mm, respectively. The porosity of the samples was measured from cross-sectional images. Biocompatibility was assessed by culturing Human Bone Marrow-Derived Mesenchymal Stromal on the surface of the printed scaffolds. The results showed that, for identical line spacing value, the highest porosity corresponded to bronzefilled material and the lowest one to steel-filled material. Steel-filled PLA polymers showed good cytocompatibility without the need to coat the material with biomolecules. Moreover, human bone marrow-derived mesenchymal stromal cells differentiated towards osteoblasts when cultured on top of the developed scaffolds. Therefore, it can be concluded that steel-filled PLA bioprinted parts are valid scaffolds for bone tissue engineeringPeer ReviewedPostprint (published version

Fabrikazio gehigarria ezinbesteko teknologia osasunean eta industrian: Euskadi eta Katalunia

Azken urteetan, fabrikazio gehigarria (FG) oso azkar garatu da hainbat sektoretan: osasuna, automobilgintza, aeronautika, etab. Aipatutako lehen sektorean, aplikazio anitzetan erabili da: prototipo eta gida kirurgikoak, scaffoldsak, inplanteak. Hobekuntza horiek gaixotasun berriei hobeto aurre egitea ahalbidetuko dute. Industriari dagokionez, fabrikazio gehigarriak aukera ematen die Industria-enpresei produktuak prozesu berri ordezko batzuen bidez fabrikatzeko (produktu eta tresna arinagoak, pertsonalizatuak, etab.), hala nola automobilgintzan edo aeronautikan. Gainera, lehen pieza horien fabrikazio-prozesuaren denbora murrizten da. Artikulu honetan, bi eskualdek (Euskal Autonomia Erkidegoa eta Katalunia), medikuntza eta industria arloetan, fabrikazio gehigarriari lotutako aktibitatea berrikusi egingo da. Osasun-aplikazioei dagokienez, bai Euskadin, bai Katalunian, FGak eragin ekonomiko bera dauka bietan; industriari dagokionez, ordea, Euskadiko ekonomian eragin handiagoa dauka Kataluniarekin alderatuta.; During the last years, Additive Manufacturing (AM) has rapidly developed in several sectors: health, automotive, aeronautics, etc. In the first sector mentioned, it has been applied in different applications: manufacturing surgical planning prototypes and guides, the use of scaffolds 3D printed, implants, etc. These improvements in the medical field will allow to have more tools to deal with new diseases, and consequently, the life expectancy will be higher. Regarding the industry, 3D printing allows the industrial companies to manufacture better products (lightweight, personalised, etc) in automation or aeronautics, for example. Additionally, there is a decrease in the process time. In present study, two different regions have been reviewed (Basque Country and Catalonia) in the medical and industrial sectors. It has been seen that in both areas AM applied to health applications has more or less the same impact in their systems. However, in terms of the industry, the Basque industry has bigger impact in the economy of the Basque Country

Fabrikazio gehigarria ezinbesteko teknologia osasunean eta industrian: Euskadi eta Katalunia

Azken urteetan, fabrikazio gehigarria (FG) oso azkar garatu da hainbat sektoretan: osasuna, automobilgintza, aeronautika, etab. Aipatutako lehen sektorean, aplikazio anitzetan erabili da: prototipo eta gida kirurgikoak, scaffoldsak, inplanteak. Hobekuntza horiek gaixotasun berriei ho-beto aurre egitea ahalbidetuko dute. Industriari dagokionez, fabrikazio gehigarriak aukera ematen die industria-enpresei produktuak prozesu berri ordezko batzuen bidez fabrikatzeko (produktu eta tresna arinagoak, pertsonalizatuak, etab.), hala nola automobilgintzan edo aeronautikan. Gainera, lehen pieza horien fabrikazio-prozesuaren denbora murrizten da. Artikulu honetan, bi eskualdek (Euskal Autono-mia Erkidegoa eta Katalunia), medikuntza eta industria arloetan, fabrikazio gehigarriari lotutako akti-bitatea berrikusi egingo da. Osasun-aplikazioei dagokienez, bai Euskadin, bai Katalunian, FGak eragin ekonomiko bera dauka bietan; industriari dagokionez, ordea, Euskadiko ekonomian eragin handiagoa dauka Kataluniarekin alderatutaPeer ReviewedPostprint (published version

Fabrikazio gehigarria ezinbesteko teknologia osasunean eta industrian: Euskadi eta Katalunia

Azken urteetan, fabrikazio gehigarria (FG) oso azkar garatu da hainbat sektoretan: osasuna, automobilgintza, aeronautika, etab. Aipatutako lehen sektorean, aplikazio anitzetan erabili da: prototipo eta gida kirurgikoak, scaffoldsak, inplanteak. Hobekuntza horiek gaixotasun berriei hobeto aurre egitea ahalbidetuko dute. Industriari dagokionez, fabrikazio gehigarriak aukera ematen die Industria-enpresei produktuak prozesu berri ordezko batzuen bidez fabrikatzeko (produktu eta tresna arinagoak, pertsonalizatuak, etab.), hala nola automobilgintzan edo aeronautikan. Gainera, lehen pieza horien fabrikazio-prozesuaren denbora murrizten da. Artikulu honetan, bi eskualdek (Euskal Autonomia Erkidegoa eta Katalunia), medikuntza eta industria arloetan, fabrikazio gehigarriari lotutako aktibitatea berrikusi egingo da. Osasun-aplikazioei dagokienez, bai Euskadin, bai Katalunian, FGak eragin ekonomiko bera dauka bietan; industriari dagokionez, ordea, Euskadiko ekonomian eragin handiagoa dauka Kataluniarekin alderatuta.; During the last years, Additive Manufacturing (AM) has rapidly developed in several sectors: health, automotive, aeronautics, etc. In the first sector mentioned, it has been applied in different applications: manufacturing surgical planning prototypes and guides, the use of scaffolds 3D printed, implants, etc. These improvements in the medical field will allow to have more tools to deal with new diseases, and consequently, the life expectancy will be higher. Regarding the industry, 3D printing allows the industrial companies to manufacture better products (lightweight, personalised, etc) in automation or aeronautics, for example. Additionally, there is a decrease in the process time. In present study, two different regions have been reviewed (Basque Country and Catalonia) in the medical and industrial sectors. It has been seen that in both areas AM applied to health applications has more or less the same impact in their systems. However, in terms of the industry, the Basque industry has bigger impact in the economy of the Basque Country

Recent advances in the extrusion methods for ceramics

In recent years, extrusion 3D printing processes have undergone an important development. They allow obtaining complex shapes in an easy way and relatively low cost. Different plastic materials can be 3D printed with the fused filament fabrication (FFF) technology. Bioinert ceramics such as alumina or zirconia have excellent physical and mechanical properties (high melting point, high strength...) that make them appropriate in different fields: medicine, electronics, etc. However, 3D printing of ceramics is by far less developed than 3D printing of plastics or metals. A possible application for 3D printing of ceramics is the manufacture of prostheses, which usually have complex shapes with porous structures. Ceramic prostheses have several advantages over the use of other materials: they generate low debris, they are hard and they are inert and corrosion-resistant. In the present work the recent advances about extrusion 3D printing of ceramic materials are presented, with a special focus on the manufacture of prosthesesPeer ReviewedPostprint (published version

Characterization of 3d printed yttria-stabilized zirconia parts for use in prostheses

The main aim of the present paper is to study and analyze surface roughness, shrinkage, porosity, and mechanical strength of dense yttria-stabilized zirconia (YSZ) samples obtained by means of the extrusion printing technique. In the experiments, both print speed and layer height were varied, according to a 22 factorial design. Cuboid samples were defined, and three replicates were obtained for each experiment. After sintering, the shrinkage percentage was calculated in width and in height. Areal surface roughness, Sa, was measured on the lateral walls of the cuboids, and total porosity was determined by means of weight measurement. The compressive strength of the samples was determined. The lowest Sa value of 9.4 m was obtained with low layer height and high print speed. Shrinkage percentage values ranged between 19% and 28%, and porosity values between 12% and 24%, depending on the printing conditions. Lowest porosity values correspond to low layer height and low print speed. The same conditions allow obtaining the highest average compressive strength value of 176 MPa, although high variability was observed. For this reason, further research will be carried out about mechanical strength of ceramic 3D printed samples. The results of this work will help choose appropriate printing conditions extrusion processes for ceramics.Peer ReviewedPostprint (published version

Research on desktop 3D Printing Multi-Material New Concepts

3D printing or Additive Manufacturing (AM) was originally born as a mono-material technology. And, nowadays, most of the applications are still using only one material. AM has a lot of potential but has not yet been fully explored, and access to the creation of multi-material products is an example of it. One of the most interesting areas is the introduction in the same part of materials with different rigidities, stiffer and softer areas, with differentiated values of mechanical strength and viscoelasticity. In the present work, a general vision of Additive Manufacturing under the vision of mono- and multi-material processes is given, and some existing 3D printing multi-material experiences related to Material Jetting (MJ) and Material Extrusion (ME) are briefly described. But it is in this latter field, linked to Desktop 3D printing (more accessible than typical proprietary industrial equipment), where on-going research could easily be spread: five research ME concepts are then presented, from a revolver print-head to silicone UV 3D printing, with their initial embodiment in the form of prototypes or/and testing, as a way to verify the difficulties that would be encountered in the transition from research to reality.Peer ReviewedPostprint (published version