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 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

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

Comparison of two-drug combinations, amikacin/tigecycline/imipenem and amikacin/tigecycline/clarithromycin against Mycobacteroides abscessus subsp. abscessus using the in vitro time-kill assay

Nontuberculous mycobacteria include 198 mycobacterial species. Among these, Mycobacteroides abscessus is a rapidly growing mycobacteria that causes lung and skin infections. M. abscessus lung infections are difficult to treat due to the high levels of resistance to several classes of antibiotics. The current treatment is based on combining at least two or three antibiotics. However, treatment outcomes remain very poor. The objective was to compare the in vitro activity of amikacin, tigecycline, imipenem, and clarithromycin, alone and in two different three-drug combinations (amikacin/tigecycline/imipenem and amikacin/tigecycline/clarithromycin) against seven M. abscessus subsp. abscessus clinical isolates using the time-kill assay. The two combinations showed greater activity than the antibiotics tested individually. Even though both combinations showed similar activity as well as no antagonistic activity, the combination including imipenem could not be an alternative treatment against M. abscessus subsp. abscessus lung infections caused by clarithromycin susceptible isolates. However, this combination could be considered against clarithromycin resistant isolates. Future studies are necessary to confirm this hypothesis

3D printed surgical planning prototype manufactured by a hybrid multi-material 3D printer

Surgical planning is a preoperative method of pre-visualization that is carried out before or during a surgical intervention in order to achieve the best outcome. This can be done either image-based or hands-on. Regarding the first strategy, it is based on the use of medical images. However, it has a huge limitation, which is the difficulty of identifying anatomical structures (crucial for surgeons to make correct decisions) and distances between tissues without any physical support. This problem is overcome with the use of 3D models. Despite this important development, until nowadays most of the surgical planning prototypes were 3D printed either using the moulding technique, which might take several days, or high-cost technologies as is material jetting. That is why, the present manuscript seeks to solve the problems arose by the use of a hybrid-multi material 3D printer which can not only use several materials at the time, but also two 3D printing technologies. The prototype introduced in this study is a neuroblastoma, a common cancer among children.Peer ReviewedPostprint (published version

Correlation between acoustic divergence and phylogenetic distance in soniferous European gobiids (Gobiidae; Gobius lineage)

In fish, species identity can be encoded by sounds, which have been thoroughly investigated in European gobiids (Gobiidae, Gobius lineage). Recent evolutionary studies suggest that deterministic and/or stochastic forces could generate acoustic differences among related animal species, though this has not been investigated in any teleost group to date. In the present comparative study, we analysed the sounds from nine soniferous gobiids and quantitatively assessed their acoustic variability. Our interspecific acoustic study, incorporating for the first time the representative acoustic signals from the majority of soniferous gobiids, suggested that their sounds are truly species-specific (92% of sounds correctly classified into exact species) and each taxon possesses a unique set of spectro-temporal variables. In addition, we reconstructed phylogenetic relationships from a concatenated molecular dataset consisting of multiple molecular markers to track the evolution of acoustic signals in soniferous gobiids. The results of this study indicated that the genus Padogobius is polyphyletic, since P. nigricans was nested within the Ponto-Caspian clade, while the congeneric P. bonelli turned out to be a sister taxon to the remaining investigated soniferous species. Lastly, by extracting the acoustic and genetic distance matrices, sound variability and genetic distance were correlated for the first time to assess whether sound evolution follows a similar phylogenetic pattern. The positive correlation between the sound variability and genetic distance obtained here emphasizes that certain acoustic features from representative sounds could carry the phylogenetic signal in soniferous gobiids. Our study was the first attempt to evaluate the mutual relationship between acoustic variation and genetic divergence in any teleost fish

In vitro activity of 12 antimicrobial peptides against Mycobacterium tuberculosis and Mycobacterium avium clinical isolates

Tuberculosis (TB) remains a major threat to human health worldwide. The increasing incidence of non-tuberculous mycobacterial infections and particularly those produced by Mycobacterium avium has emphasized the need to develop new drugs. Additionally, high levels of natural drug resistance in non-tuberculous mycobacteria (NTM) and the emergence of multidrug-resistant (MDR) TB is of great concern. Antimicrobial peptides (AMPs) are antibiotics with broad-spectrum antimicrobial activity. The objective was to assess the activity of AMPs against Mycobacterium tuberculosis and M. avium clinical isolates. MICs were determined using microtitre plates and the resazurin assay. Mastoparan and melittin showed the greatest activity against M. tuberculosis, while indolicidin had the lowest MIC against M. avium. In conclusion, AMPs could be alternatives for the treatment of mycobacterial infections. Further investigation of AMPs' activity in combination and associated with conventional antibiotics and their loading into drug-delivery systems could lead to their use in clinical practice