Progressive 3D Printing Technology and Its Application in Medical Materials

Cranial Defect Repair With 3D Designed Models

Cranioplasty is one of the most common neurosurgical procedure performed to repair cranial defect. Many materials and fabrication technique are used to prepare cranial implant in cases where autologous bone is not available. Polymethyl Methacrylate (PMMA) is one of the most common polymer used as bone substitute. PMMA fabricated using 3D printed models have shown better fit, symmetrical shape, and restore esthetic looks of patients. The use of 3D printed implants in medical procedures has several advantages over traditional manufacturing methods. 3D printing allows for greater precision, customization, and quicker implant time.

Utilizing Food Waste in 3D-Printed PLA Formulations to Achieve Sustainable and Customizable Controlled Delivery Systems

This is the first study that explores blending polylactic acid (PLA) with various biomasses, including food wastes-brewer's spent grain (BSG), spent coffee grounds (SCG), sesame cake (SC), and thermoplastic starch (TPS) biomass to create composite gastric floating drug delivery systems (GFDDS) through 3D printing. The aim is to investigate the influence of biomass percentage, biomass type, and printing parameters on their corresponding drug release profiles. 3D-printed (3DP) composite filaments were prepared by blending biomasses and PLA before in vitro drug release studies were performed using hydrophilic and hydrophobic model drugs, metoprolol tartrate (MT), and risperidone (RIS). The data revealed that release profiles were influenced by composite compositions and wall thicknesses of 3DP GFDDS capsules. Up to 15% of food waste could be blended with PLA for all food waste types tested. Delivery studies for PLA-food wastes found that MT was fully released by 4 h, exhibiting burst release profiles after a lag time of 0.5 to 1.5 h, and RIS could achieve a sustained release profile of approximately 48 h. PLA-TPS was utilized as a comparison and demonstrated variable release profiles ranging from 8 to 120 h, depending on the TPS content. The results demonstrated the potential for adjusting drug release profiles by incorporating affordable biomasses into GFDDS. This study presents a promising direction for creating delivery systems that are sustainable, customizable, and cost-effective, utilizing sustainable materials that can also be employed for agricultural, nutraceutical, personal care, and wastewater treatment applications.

Advancements in Custom 3D-Printed Titanium Interbody Spinal Fusion Cages and Their Relevance in Personalized Spine Care

3D-printing technology has revolutionized spinal implant manufacturing, particularly in developing personalized and custom-fit titanium interbody fusion cages. These cages are pivotal in supporting inter-vertebral stability, promoting bone growth, and restoring spinal alignment. This article reviews the latest advancements in 3D-printed titanium interbody fusion cages, emphasizing their relevance in modern personalized surgical spine care protocols applied to common clinical scenarios. Furthermore, the authors review the various printing and post-printing processing technologies and discuss how engineering and design are deployed to tailor each type of implant to its patient-specific clinical application, highlighting how anatomical and biomechanical considerations impact their development and manufacturing processes to achieve optimum osteoinductive and osteoconductive properties. The article further examines the benefits of 3D printing, such as customizable geometry and porosity, that enhance osteointegration and mechanical compatibility, offering a leap forward in patient-specific solutions. The comparative analysis provided by the authors underscores the unique challenges and solutions in designing cervical, and lumbar spine implants, including load-bearing requirements and bioactivity with surrounding bony tissue to promote cell attachment. Additionally, the authors discuss the clinical outcomes associated with these implants, including the implications of improvements in surgical precision on patient outcomes. Lastly, they address strategies to overcome implementation challenges in healthcare facilities, which often resist new technology acquisitions due to perceived cost overruns and preconceived notions that hinder potential savings by providing customized surgical implants with the potential for lower complication and revision rates. This comprehensive review aims to provide insights into how modern 3D-printed titanium interbody fusion cages are made, explain quality standards, and how they may impact personalized surgical spine care.

An overview of nasal cartilage bioprinting: from bench to bedside

Nasal cartilage diseases and injuries are known as significant challenges in reconstructive medicine, affecting a substantial number of individuals worldwide. In recent years, the advent of three-dimensional (3D) bioprinting has emerged as a promising approach for nasal cartilage reconstruction, offering potential breakthroughs in the field of regenerative medicine. This paper provides an overview of the methods and challenges associated with 3D bioprinting technologies in the procedure of reconstructing nasal cartilage tissue. The process of 3D bioprinting entails generating a digital 3D model using biomedical imaging techniques and computer-aided design to integrate both internal and external scaffold features. Then, bioinks which consist of biomaterials, cell types, and bioactive chemicals, are applied to facilitate the precise layer-by-layer bioprinting of tissue-engineered scaffolds. After undergoing in vitro and in vivo experiments, this process results in the development of the physiologically functional integrity of the tissue. The advantages of 3D bioprinting encompass the ability to customize scaffold design, enabling the precise incorporation of pore shape, size, and porosity, as well as the utilization of patient-specific cells to enhance compatibility. However, various challenges should be considered, including the optimization of biomaterials, ensuring adequate cell viability and differentiation, achieving seamless integration with the host tissue, and navigating regulatory attention. Although numerous studies have demonstrated the potential of 3D bioprinting in the rebuilding of such soft tissues, this paper covers various aspects of the bioprinted tissues to provide insights for the future development of repair techniques appropriate for clinical use.

Development of a Cost-Effective 3D-Printed Airway Suction Simulator for Respiratory Therapy Students

BACKGROUND

Three-dimensional (3D)-printed models are cost-effective and can be customized by trainers. This study designed a 3D-printed airway suction simulator for use by respiratory therapy (RT) students. The objective was to demonstrate the cost-effectiveness and application of 3D-printed models in respiratory care training, aiming to enhance the educational experience for RT students.

METHODS

This study developed a 3D-printed airway suction simulator that was cost-effective. A randomized controlled trial was conducted involving RT students to compare effectiveness in a 3D-model group and a control group. Skill assessments and written examinations were used to evaluate the participants' knowledge and skills.

RESULTS

A total of 38 second-year RT students were randomly assigned to either the 3D-model group (n = 19) or the control group (n = 19). One participant in the 3D-model group was lost to follow-up during the planned direct observation of procedural skills (DOPS) assessment and satisfaction questionnaire completion. The posttest written examination scores were significantly higher in the 3D-model group than in the control group (100% vs 80%, P = .02). The scores from the DOPS and satisfaction questionnaire were comparable in the 2 groups.

CONCLUSIONS

This study demonstrated that 3D printing can be used to create a safe and cost-effective airway suction simulator for use by RT students, with potential to enhance training methods. Further research is necessary.

Perspectives on 3D printed personalized medicines for pediatrics

In recent years, the rapid advancement of three-dimensional (3D) printing technology has yielded distinct benefits across various sectors, including pharmaceuticals. The pharmaceutical industry has particularly experienced advantages from the utilization of 3D-printed medications, which have invigorated the development of tailored drug formulations. The approval of 3D-printed drugs by the U.S. Food and Drug Administration (FDA) has significantly propelled personalized drug delivery. Additionally, 3D printing technology can accommodate the precise requirements of pediatric drug dosages and the complexities of multiple drug combinations. This review specifically concentrates on the application of 3D printing technology in pediatric preparations, encompassing a broad spectrum of uses and refined pediatric formulations. It compiles and evaluates the fundamental principles associated with the application of 3D printing technology in pediatric preparations, including its merits and demerits, and anticipates its future progression. The objective is to furnish theoretical underpinning for 3D printing technology to facilitate personalized drug delivery in pediatrics and to advocate for its implementation in clinical settings.

HPMC/PVP K90 Dissolving Microneedles Fabricated from 3D-Printed Master Molds: Impact on Microneedle Morphology, Mechanical Strength, and Topical Dissolving Property

Three-dimensional (3D) printing can be used to fabricate custom microneedle (MN) patches instead of the conventional method. In this work, 3D-printed MN patches were utilized to fabricate a MN mold, and the mold was used to prepare dissolving MNs for topical lidocaine HCl (L) delivery through the skin. Topical creams usually take 1-2 h to induce an anesthetic effect, so the delivery of lidocaine HCl from dissolving MNs can allow for a therapeutic effect to be reached faster than with a topical cream. The dissolving-MN-patch-incorporated lidocaine HCl was constructed from hydroxypropyl methylcellulose (HPMC; H) and polyvinyl pyrrolidone (PVP K90; P) using centrifugation. Additionally, the morphology, mechanical property, skin insertion, dissolving behavior, drug-loading content, drug release of MNs and the chemical interactions among the compositions were also examined. H51P2-L, H501P2-L, and H901P2-L showed an acceptable needle appearance without bent tips or a broken structure, and they had a low % height change (<10%), including a high blue-dot percentage on the skin (>80%). These three formulations exhibited a drug-loading content approaching 100%. Importantly, the composition-dependent dissolving abilities of MNs were revealed. Containing the lowest amount of HPMC in its formulation, H901P2-L showed the fastest dissolving ability, which was related to the high amount of lidocaine HCl released through the skin. Moreover, the results of an FTIR analysis showed no chemical interactions among the two polymers and lidocaine HCl. As a result, HPMC/PVP K90 dissolving microneedles can be used to deliver lidocaine HCl through the skin, resulting in a faster onset of anesthetic action.

Microfluidic printed 3D bioactive scaffolds for postoperative treatment of gastric cancer

Tumor recurrence and tissue regeneration are two major challenges in the postoperative treatment of cancer. Current research hotspots are focusing on developing novel scaffold materials that can simultaneously suppress tumor recurrence and promote tissue repair. Here, we propose a microfluidic 3D-printed methacrylate fish gelatin (F-GelMA@BBR) scaffold loaded with berberine (BBR) for the postoperative treatment of gastric cancer. The F-GelMA@BBR scaffold displayed a significant killing effect on gastric cancer MKN-45 cells in vitro and demonstrated excellent anti-recurrence efficiency in gastric cancer postoperative models. In vitro experiments have shown that F-GelMA@BBR exhibits significant cytotoxicity on gastric cancer cells while maintaining the cell viability of normal cells. The results of in vivo experiments show that F-GelMA@BBR can significantly suppress the tumor volume to 49.7 % of the control group. In addition, the scaffold has an ordered porous structure and good biocompatibility, which could support the attachment and proliferation of normal cells to promote tissue repair at the tumor resection site. These features indicated that such scaffold material is a promising candidate for postoperative tumor treatment in the practical application.

The Use and Outcomes of 3D Printing in Pediatric Craniofacial Surgery: A Systematic Review

Three-dimensional (3D) printing has demonstrated efficacy in multiple surgical specialties. As accessibility improves, its use in specific fields deserves further attention. We conducted a systematic review of the implementation and outcomes of 3D printing in pediatric craniofacial surgery, as none has been performed. A systematic review was conducted according to Cochrane and PRISMA guidelines. PubMed, Embase, Cochrane library, and Clinicaltrials.gov were queried with combinations of the terms: "3D printing," "craniofacial," "surgery," and "pediatric." Original human studies containing patients <18 years old implementing 3D printing to aid in craniofacial surgery were included. Study selection, grading, and data extraction were performed independently by multiple authors. After screening 120 articles, 7 (3 case series and 4 case reports) were included, published from 2017 to 2022. All studies addressed patients with different disease processes including craniosynostosis, cleft lip/palate, and mandibular hypoplasia. 3D printing was used to create mock surgical models in 2 studies, intraoperative cutting guides/molds (CGs) in 6 studies, and cranioplasty implants in 2 studies. Two case series determined the accuracy of the CGs was acceptable within historical comparison, while 4 articles included subjective statements on improved accuracy. Five studies noted reduced operating time, 2 noted reduced intraoperative blood loss, and 1 felt the use of 3D printed materials was responsible for shorter hospitalization duration. No adverse events were reported. Despite the limitations of the current literature, all studies concluded that the use of 3D printing in pediatric craniofacial surgery was beneficial. Definitive conclusions cannot be made until further controlled research is performed.

3D-printed prednisolone phosphate suppositories with tunable dose and rapid release for the treatment of inflammatory bowel disease

Established medicines are often not tailored to the needs of the pediatric population, causing difficulties with administration or dosing. Three-dimensional (3D) printing technology allows novel approaches for compounding of personalized medicine, as is exemplified in this study for the automated compounding of rectal preparations for children. We investigated the material requirements to print prednisolone phosphate-loaded suppositories with tunable dose and rapid drug release for the treatment of inflammatory bowel diseases. Three formulations containing 4 % w/w prednisolone sodium phosphate (PSP) and different amounts of hydroxypropyl cellulose (HPC) and mannitol as excipients were printed as suppositories with a fused deposition modeling (FDM) 3D-printer. Dissolution studies showed that the PSP release rate was increased when higher weight fractions of mannitol were added as a pore former, with 90 % drug release within 30 min for mannitol 48 % w/w. We further printed suppositories with 48 % mannitol with different infill densities and dimensions to tune the dose. Our findings demonstrated that 3D-printed suppositories with PSP doses ranging from 6 to 30 mg could be compounded without notably affecting the dissolution kinetics, ensuring equivalent therapeutic efficacies for different doses.

Three-Dimensional Printing as a Progressive Innovative Tool for Customized and Precise Drug Delivery

While using three-dimensional printing, materials are deposited layer by layer in accordance with the digital model created by computer-aided design software. Numerous research teams have shown interest in this technology throughout the last few decades to produce various dosage forms in the pharmaceutical industry. The number of publications has increased since the first printed medicine was approved in 2015 by Food and Drug Administration. Considering this, the idea of creating complex, custom-made structures that are loaded with pharmaceuticals for tissue engineering and dose optimization is particularly intriguing. New approaches and techniques for creating unique medication delivery systems are made possible by the development of additive manufacturing keeping in mind the comparative advantages it has over conventional methods of manufacturing medicaments. This review focuses on three-dimensional printed formulations grouped in orally disintegrated tablets, buccal films, implants, suppositories, and microneedles. The various types of techniques that are involved in it are summarized. Additionally, challenges and applications related to three-dimensional printing of pharmaceuticals are also being discussed.

A feasibility study of several 3D printing methods for applications in epilepsy surgery

OBJECTIVE

To describe the process of three-dimensional printing in epilepsy surgery using three different methods: low-force stereolithography (SLA), filament deposition modeling (FDM), and Polyjet Stratasys, while comparing them in terms of printing efficiency, cost, and clinical utility. MRI and CT images of patient anatomy have been limited to review in the two-dimensional plane, which provides only partial representation of intricate intracranial structures. There has been growing interest in 3D printing of physical models of this complex anatomy to be used as an educational tool and for surgical visualization. One specific application is in epilepsy surgery where there are challenges in visualizing complex intracranial anatomy in relation to implanted surgical tools.

METHODS

MRI and CT data from patients with refractory epilepsy from a single center that underwent surgery are converted into 3D volumes, or stereolithography files. These were then printed using three popular 3D printing methods: SLA, FDM, and Polyjet. Faculty were surveyed on the impact of 3D modeling on the surgical planning process.

RESULTS

All three methods generated physical models with an increasing degree of resolution, transparency, and clinical utility directly related to cost of production and accurate representation of anatomy. Polyjet models were the most transparent and clearly represented intricate implanted electrodes but had the highest associated cost. FDM produced relatively inexpensive models that, however, were nearly completely opaque, limiting clinical utility. SLA produced economical and highly transparent models but was limited by single material capacity.

SIGNIFICANCE

Three-dimensional printing of patient-specific anatomy is feasible with a variety of printing methods. The clinical utility of lower-cost methods is limited by model transparency and lack of multi-material overlay respectively. Polyjet successfully generated transparent models with high resolution of internal structures but is cost-prohibitive. Further research needs to be done to explore cost-saving methods of modeling.

Multipotent Mesenchymal Cells Homing and Differentiation on Poly(ε-caprolactone) Blended with 20% Tricalcium Phosphate and Polylactic Acid Incorporating 10% Hydroxyapatite 3D-Printed Scaffolds via a Commercial Fused Deposition Modeling 3D Device

As highlighted by the 'Global Burden of Disease Study 2019' conducted by the World Health Organization, ensuring fair access to medical care through affordable and targeted treatments remains crucial for an ethical global healthcare system. Given the escalating demand for advanced and urgently needed solutions in regenerative bone procedures, the critical role of biopolymers emerges as a paramount necessity, offering a groundbreaking avenue to address pressing medical needs and revolutionize the landscape of bone regeneration therapies. Polymers emerge as excellent solutions due to their versatility, making them reliable materials for 3D printing. The development and widespread adoption of this technology would impact production costs and enhance access to related healthcare services. For instance, in dentistry, the use of commercial polymers blended with β-tricalcium phosphate (TCP) is driven by the need to print a standardized product with osteoconductive features. However, modernization is required to bridge the gap between biomaterial innovation and the ability to print them through commercial printing devices. Here we showed, for the first time, the metabolic behavior and the lineage commitment of bone marrow-derived multipotent mesenchymal cells (MSCs) on the 3D-printed substrates poly(e-caprolactone) combined with 20% tricalcium phosphate (PCL + 20% β-TCP) and L-polylactic acid (PLLA) combined with 10% hydroxyapatite (PLLA + 10% HA). Although there are limitations in printing additive-enriched polymers with a predictable and short half-life, the tested 3D-printed biomaterials were highly efficient in supporting osteoinductivity. Indeed, considering different temporal sequences, both 3D-printed biomaterials resulted as optimal scaffolds for MSCs' commitment toward mature bone cells. Of interest, PLLA + 10% HA substrates hold the confirmation as the finest material for osteoinduction of MSCs.

Biocomposite-based strategies for dental bone regeneration

OBJECTIVE

Because of the anatomical complexity of the oral and maxillofacial sites, repairing bone defects in these regions is very difficult. This review article aims to consider the application of biocomposites-based strategies for dental bone regeneration.

STUDY DESIGN

Research papers related to the topic, published over the last 20 years, were selected using the Web of Science, Pubmed, Scopus, and Google Scholar databases.

RESULTS

The strategies of monophasic, biphasic/multiphasic scaffolds, and biopolymer-based nanocomposite scaffolds containing nanomaterials compared with traditional methods used for bone regeneration, such as autografts, allografts, xenografts, and alloplasts are found to be superior because of their ability to overcome the issues (e.g., limited bone sources, pain, immune responses, high cost) related to the applications of the traditional methods.

CONCLUSIONS

In addition, additive manufacturing technologies were found to be highly advantageous for improving the efficacy of biocomposite scaffolds for treating dental bone defects.

A 3D-Printed Portable Sterilizer to Be Used During Surgical Procedures in Spaceflight

INTRODUCTION: During spaceflight, it is important to consider the mechanisms by which surgeries and medical procedures can be safely and efficiently conducted. Instruments used to carry out these processes need to be sterilized. Thus, we have designed and tested a three-dimensional-printed (3D-printed) portable sterilizer that implements far ultraviolet-C (Far UV-C) light radiation to disinfect bacteria and microorganisms from surgical instruments.METHODS: The sterilizer was 3D-printed with polylactic acid filament. Effectiveness was assessed through three trials at differing times of sterilization and compared against a control group of no sterilization and against Clorox wipes. Cultures were incubated on agar dishes and counted with ImageJ.RESULTS: Increasing time under Far UV-C light radiation increased the percentage of sterilization up to 100% at 10 min. The 3D-printed sterilizer was significantly better than Clorox wipes and control.DISCUSSION: As sterilization will be necessary for surgical procedures in microgravity and upmass is a significant concern, we have successfully demonstrated a 3D-printable portable sterilizer for surgical instruments that achieves 100% success in using Far UV-C light to disinfect its surface of bacteria with a 10-min sterilizing time. Further research is necessary to test this design in microgravity and with differently sized and shaped instruments.Kovalski E, Salazar L, Levin D, Kamine TH. A 3D-printed portable sterilizer to be used during surgical procedures in spaceflight. Aerosp Med Hum Perform. 2023; 94(11):857-860.

Development of an anti-infective urinary catheter composed of polyvinyl alcohol/sodium alginate/methylcellulose/polyethylene glycol by using a pressure-assisted 3D-printing technique

Catheter-associated urinary tract infections (CAUTI) are a common complication associated with catheterization, leading to urosepsis, bacteriuria, and septicaemia. The present work focuses on 3D printing a urinary catheter with anti-infective properties using various concentrations of polyvinyl alcohol (PVA, e.g., 6-8 %), sodium alginate (NaAlg, e.g. 1-4 %), methylcellulose (MC, 5 %), polyethylene glycol (PEG, 5 %) impregnated with secnidazole, an antibiotic acting against Gram-negative bacteria. To produce suitable polymer ink for Pressure Assisted Microsyringe (PAM) 3D printing, the cross-linked between NaAlg and calcium chloride is necessary to prepare the catheter. The optimised catheter was found to have an outer diameter of 5 mm, an inner diameter of 3.5 mm, and a length of the catheter of 50 mm. The analysis by various methods confirms the successful incorporation of secnidazole in the 3D-printed catheter. A drug-loaded/coated catheter showed an initial drug release of 79 % following a sustained release to reach 100 % within 5 h. Weibull model fits well with the drug release data. The release models suggest the Quasi-Fickian diffusion mechanism from the system. Moreover, the secnidazole 3D printed catheter disrupted biofilms and suppressed all the Quorum sensing mediated virulence factors of two important keystone pathogens causing urinary tract infections.

Recent Progress and Trends in the Development of Electrospun and 3D Printed Polymeric-Based Materials to Overcome Antimicrobial Resistance (AMR)

Antimicrobial resistance (AMR) developed by microorganisms is considered one of the most critical public health issues worldwide. This problem is affecting the lives of millions of people and needs to be addressed promptly. Mainly, antibiotics are the substances that contribute to AMR in various strains of bacteria and other microorganisms, leading to infectious diseases that cannot be effectively treated. To avoid the use of antibiotics and similar drugs, several approaches have gained attention in the fields of materials science and engineering as well as pharmaceutics over the past five years. Our focus lies on the design and manufacture of polymeric-based materials capable of incorporating antimicrobial agents excluding the aforementioned substances. In this sense, two of the emerging techniques for materials fabrication, namely, electrospinning and 3D printing, have gained significant attraction. In this article, we provide a summary of the most important findings that contribute to the development of antimicrobial systems using these technologies to incorporate various types of nanomaterials, organic molecules, or natural compounds with the required property. Furthermore, we discuss and consider the challenges that lie ahead in this research field for the coming years.

Metal and Polymer Based Composites Manufactured Using Additive Manufacturing-A Brief Review

This review examines the mechanical performance of metal- and polymer-based composites fabricated using additive manufacturing (AM) techniques. Composite materials have significantly influenced various industries due to their exceptional reliability and effectiveness. As technology advances, new types of composite reinforcements, such as novel chemical-based and bio-based, and new fabrication techniques are utilized to develop high-performance composite materials. AM, a widely popular concept poised to shape the development of Industry 4.0, is also being utilized in the production of composite materials. Comparing AM-based manufacturing processes to traditional methods reveals significant variations in the performance of the resulting composites. The primary objective of this review is to offer a comprehensive understanding of metal- and polymer-based composites and their applications in diverse fields. Further on this review delves into the intricate details of metal- and polymer-based composites, shedding light on their mechanical performance and exploring the various industries and sectors where they find utility.

Fabrication of a composite 3D-printed titanium alloy combined with controlled in situ drug release to prevent osteosarcoma recurrence

Osteosarcoma is a malignant bone tumor occurring in adolescents. Surgery combined with adjuvant or neoadjuvant chemotherapy is the standard treatment. However, systemic chemotherapy is associated with serious side effects and a high risk of postoperative tumor recurrence, leading to a high amputation rate and mortality in cancer patients. Implant materials that can simultaneously repair large bone defects and prevent osteosarcoma recurrence are in urgent need. Herein, an intelligent system comprising 3D-printed titanium scaffold (TS) and pH-responsive PEGylated paclitaxel prodrugs was fabricated for bone defect reconstruction and recurrence prevention following osteosarcoma surgery. The drug-loaded implants exhibited excellent stability and biocompatibility for supporting the activity of bone stem cells under normal body fluid conditions and the rapid release of drugs in response to faintly acidic environments. An in vitro study demonstrated that five human osteosarcoma cell lines could be efficiently eradicated by paclitaxel released in an acidic microenvironment. Using mice models, we demonstrated that the drug-loaded TS can enable a pH-responsive treatment of postoperative tumors and effectively prevent osteosarcoma recurrence. Therefore, local implantation of this composite scaffold may be a promising topical therapeutic method to prevent osteosarcoma recurrence.

Three Dimensional Printing and Its Applications Focusing on Microneedles for Drug Delivery

Microneedles (MNs) are considered to be a novel smart injection system that causes significantly low skin invasion upon puncturing, due to the micron-sized dimensions that pierce into the skin painlessly. This allows transdermal delivery of numerous therapeutic molecules, such as insulin and vaccines. The fabrication of MNs is carried out through conventional old methods such as molding, as well as through newer and more sophisticated technologies, such as three-dimensional (3D) printing, which is considered to be a superior, more accurate, and more time- and production-efficient method than conventional methods. Three-dimensional printing is becoming an innovative method that is used in education through building intricate models, as well as being employed in the synthesis of fabrics, medical devices, medical implants, and orthoses/prostheses. Moreover, it has revolutionary applications in the pharmaceutical, cosmeceutical, and medical fields. Having the capacity to design patient-tailored devices according to their dimensions, along with specified dosage forms, has allowed 3D printing to stand out in the medical field. The different techniques of 3D printing allow for the production of many types of needles with different materials, such as hollow MNs and solid MNs. This review covers the benefits and drawbacks of 3D printing, methods used in 3D printing, types of 3D-printed MNs, characterization of 3D-printed MNs, general applications of 3D printing, and transdermal delivery using 3D-printed MNs.

Three-Dimensional Printed Knee Implants: Insights into Surgeons' Points of View

Three-dimensional printing is a technology that has been developed and applied in several medical specialties, especially orthopedic surgery. Knee arthroplasty is the most commonly performed procedure. To fit the morphology of each knee, surgeons can choose between different standardized off-the-shelf implant sizes or opt for customized 3D-printed implants. However, routine adoption of the latter has been slow and faces several barriers. Existing studies focus on technical improvements or case studies and do not directly address the surgeon's perspective. Our study invited surgeons to express themselves freely and answer the question "What do you think about the manufacture of a prosthesis by 3D printing?". The questionnaire was completed by 90 surgeons. On average, they had more than 10 years of experience (52, 57.8% ± 10.2%), worked in public hospitals (54, 60% ± 10.1%), and performed between 0 and 100 prostheses per year (60, 66.7% ± 9.7%). They also reported not using planning software (47, 52.2% ± 9.7%), navigation systems, or robots (62, 68.9% ± 9.6%). Regarding the use of technological innovation, they agreed on the extra surgical time needed (67, 74.4% ± 9.0%). The answers obtained were classified according to two criteria: (i) opinions, and (ii) motivations. Among the respondents, 51 (70% ± 9.5%) had positive and 22 (30% ± 9.5%) had negative opinions about 3D printing. The motivations were distributed among seven categories (surgery, materials, costs, logistics, time, customization, and regulatory) and mainly related to "pre-surgery" and "post-surgery" concerns. Finally, the results showed that the use of navigation systems or robots may be associated with a more positive view of 3DP. The purpose of our study was to examine knee surgeons' perceptions of 3DP at a time of significant expansion of this technology. Our study showed that there was no opposition to its implementation, although some surgeons indicated that they were waiting for validated results. They also questioned the entire supply chain, including hospitals, insurance companies, and manufacturers. Although there was no opposition to its implementation, 3D printing is at a crucial point in its development and its full adoption will require advances in all areas of joint replacement.

Utility and Costs During the Initial Year of 3D Printing in an Academic Hospital

OBJECTIVE

There is a paucity of utility and cost data regarding the launch of 3D printing in a hospital. The objective of this project is to benchmark utility and costs for radiology-based in-hospital 3D printing of anatomic models in a single, adult academic hospital.

METHODS

All consecutive patients for whom 3D printed anatomic models were requested during the first year of operation were included. All 3D printing activities were documented by the 3D printing faculty and referring specialists. For patients who underwent a procedure informed by 3D printing, clinical utility was determined by the specialist who requested the model. A new metric for utility termed Anatomic Model Utility Points with range 0 (lowest utility) to 500 (highest utility) was derived from the specialist answers to Likert statements. Costs expressed in United States dollars were tallied from all 3D printing human resources and overhead. Total costs, focused costs, and outsourced costs were estimated. The specialist estimated the procedure room time saved from the 3D printed model. The time saved was converted to dollars using hospital procedure room costs.

RESULTS

The 78 patients referred for 3D printed anatomic models included 11 clinical indications. For the 68 patients who had a procedure, the anatomic model utility points had an overall mean (SD) of 312 (57) per patient (range, 200-450 points). The total operation cost was $213,450. The total cost, focused costs, and outsourced costs were $2,737, $2,180, and $2,467 per model, respectively. Estimated procedure time saved had a mean (SD) of 29.9 (12.1) min (range, 0-60 min). The hospital procedure room cost per minute was $97 (theoretical $2,900 per patient saved with model).

DISCUSSION

Utility and cost benchmarks for anatomic models 3D printed in a hospital can inform health care budgets. Realizing pecuniary benefit from the procedure time saved requires future research.

Meta-analyzing the efficacy of 3D printed models in anatomy education

Three-dimensional printing models (3DPs) have been widely used in medical anatomy training. However, the 3DPs evaluation results differ depending on such factors as the training objects, experimental design, organ parts, and test content. Thus, this systematic evaluation was carried out to better understand the role of 3DPs in different populations and different experimental designs. Controlled (CON) studies of 3DPs were retrieved from PubMed and Web of Science databases, where the participants were medical students or residents. The teaching content is the anatomical knowledge of human organs. One evaluation indicator is the mastery of anatomical knowledge after training, and the other is the satisfaction of participants with 3DPs. On the whole, the performance of the 3DPs group was higher than that of the CON group; however, there was no statistical difference in the resident subgroup, and there was no statistical difference for 3DPs vs. 3D visual imaging (3DI). In terms of satisfaction rate, the summary data showed that the difference between the 3DPs group (83.6%) vs. the CON group (69.6%) (binary variable) was not statistically significant, with p > 0.05. 3DPs has a positive effect on anatomy teaching, although there are no statistical differences in the performance tests of individual subgroups; participants generally had good evaluations and satisfaction with 3DPs. 3DPs still faces challenges in production cost, raw material source, authenticity, durability, etc. The future of 3D-printing-model-assisted anatomy teaching is worthy of expectation.

Gamma Irradiation Processing on 3D PCL Devices-A Preliminary Biocompatibility Assessment

Additive manufacturing or 3D printing applying polycaprolactone (PCL)-based medical devices represents an important branch of tissue engineering, where the sterilization method is a key process for further safe application in vitro and in vivo. In this study, the authors intend to access the most suitable gamma radiation conditions to sterilize PCL-based scaffolds in a preliminary biocompatibility assessment, envisioning future studies for airway obstruction conditions. Three radiation levels were considered, 25 kGy, 35 kGy and 45 kGy, and evaluated as regards their cyto- and biocompatibility. All three groups presented biocompatible properties, indicating an adequate sterility condition. As for the cytocompatibility analysis, devices sterilized with 35 kGy and 45 kGy showed better results, with the 45 kGy showing overall improved outcomes. This study allowed the selection of the most suitable sterilization condition for PCL-based scaffolds, aiming at immediate future assays, by applying 3D-customized printing techniques to specific airway obstruction lesions of the trachea.

3D printing of bone and cartilage with polymer materials

Damage and degeneration to bone and articular cartilage are the leading causes of musculoskeletal disability. Commonly used clinical and surgical methods include autologous/allogeneic bone and cartilage transplantation, vascularized bone transplantation, autologous chondrocyte implantation, mosaicplasty, and joint replacement. 3D bio printing technology to construct implants by layer-by-layer printing of biological materials, living cells, and other biologically active substances in vitro, which is expected to replace the repair mentioned above methods. Researchers use cells and biomedical materials as discrete materials. 3D bio printing has largely solved the problem of insufficient organ donors with the ability to prepare different organs and tissue structures. This paper mainly discusses the application of polymer materials, bio printing cell selection, and its application in bone and cartilage repair.

Production of 3D Printed Bi-Layer and Tri-Layer Sandwich Scaffolds with Polycaprolactone and Poly (vinyl alcohol)-Metformin towards Diabetic Wound Healing

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by impaired insulin secretion, sensitivity, and hyperglycemia. Diabetic wounds are one of the significant complications of T2DM owing to its difficulty in normal healing, resulting in chronic wounds. In the present work, PCL/PVA, PCL/PVA/PCL, and metformin-loaded, PCL/PVA-Met and PCL/PVA-Met/PCL hybrid scaffolds with different designs were fabricated using 3D printing. The porosity and morphological analysis of 3D-printed scaffolds were performed using scanning electron microscopy (SEM). The scaffolds' average pore sizes were between 63.6 ± 4.0 and 112.9 ± 3.0 μm. Molecular and chemical interactions between polymers and the drug were investigated with Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Mechanical, thermal, and degradation analysis of the scaffolds were undertaken to investigate the physico-chemical characteristics of the scaffolds. Owing to the structure, PCL/PVA/PCL sandwich scaffolds had lower degradation rates than the bi-layer scaffolds. The drug release of the metformin-loaded scaffolds was evaluated with UV spectrometry, and the biocompatibility of the scaffolds on fibroblast cells was determined by cell culture analysis. The drug release in the PCL/PVA-Met scaffold was sustained till six days, whereas in the PCL/PVA-Met/PCL, it continued for 31 days. In the study of drug release kinetics, PCL/PVA-Met and PCL/PVA-Met/PCL scaffolds showed the highest correlation coefficients (R²) values for the first-order release model at 0.8735 and 0.889, respectively. Since the layered structures in the literature are mainly obtained with the electrospun fiber structures, these biocompatible sandwich scaffolds, produced for the first time with 3D-printing technology, may offer an alternative to existing drug delivery systems and may be a promising candidate for enhancing diabetic wound healing.

Accelerating 3D printing of pharmaceutical products using machine learning

Three-dimensional printing (3DP) has seen growing interest within the healthcare industry for its ability to fabricate personalized medicines and medical devices. However, it may be burdened by the lengthy empirical process of formulation development. Active research in pharmaceutical 3DP has led to a wealth of data that machine learning could utilize to provide predictions of formulation outcomes. A balanced dataset is critical for optimal predictive performance of machine learning (ML) models, but data available from published literature often only include positive results. In this study, in-house and literature-mined data on hot melt extrusion (HME) and fused deposition modeling (FDM) 3DP formulations were combined to give a more balanced dataset of 1594 formulations. The optimized ML models predicted the printability and filament mechanical characteristics with an accuracy of 84%, and predicted HME and FDM processing temperatures with a mean absolute error of 5.5 °C and 8.4 °C, respectively. The performance of these ML models was better than previous iterations with a smaller and a more imbalanced dataset, highlighting the importance of providing a structured and heterogeneous dataset for optimal ML performance. The optimized models were integrated in an updated web-application, M3DISEEN, that provides predictions on filament characteristics, printability, HME and FDM processing temperatures, and drug release profiles (https://m3diseen.com/predictionsFDM/). By simulating the workflow of preparing FDM-printed pharmaceutical products, the web-application expedites the otherwise empirical process of formulation development, facilitating higher pharmaceutical 3DP research throughput.

Mechanically tunable resins based on acrylate-based resin for digital light processing (DLP) 3D printing

Until now, only a few materials are available for additive manufacturing technologies that employ photopolymerization, such as stereolithography (SLA) and digital light processing (DLP) 3D printing systems. This study investigates a newly formulated resins as an alternative 3D printing materials with tunable mechanical properties to expand the potential applications of advanced engineering products such as wearable devices and small reactors. A commercial acrylate-based resin was selected as a standard resin (STD). The resin was formulated by combining various volume ratios of a low-cost polypropylene glycol (PPG) having various molecular weights (400, 1000, and 2000 g/mol) with the STD resin. The printability of the formulated resins was optimized using the digital light processing (DLP) 3D printing technique. The effects of the PPG contents on the properties of the printed parts were studied, including printability, thermal properties, mechanical properties, and thermo-mechanical properties. As a result, the formulated resins with 5–30%vol of PPG could be printed while higher PPG content led to print failure. Results suggest that increasing the PPG contents reduced the dimensional accuracy of the printed parts and decreased the mechanical properties, including the flexural strength, flexural modulus, impact strength, hardness, and elastic modulus. interestingly, at small loading, 5%vol, the mechanical performance of the printed specimens was successfully enhanced. These results are intriguing to use a tunable mechanical acrylate-based resin for a specific application such as a microreactor.

3D printing biocompatible materials with Multi Jet Fusion for bioreactor applications

In the evolving three-dimensional (3D) printing technology, the involvement of different materials in any new 3D printing process necessitates a thorough evaluation of the product's biocompatibility for biomedical application. Here, we examined the ability of Multi Jet Fusion (MJF)-printed PA-12 to support cell proliferation and osteogenesis. Our results show that leachate from MJF-printed PA-12 does not inhibit the growth of L929 fibroblast and MC3T3e1 osteoblast. The substrate supports the attachment and proliferation of both cell types, though not at a level comparable to conventional polystyrene culture plate. Neither plasma treatment, poly-D-lysine, nor collagen coatings narrowed the gap substantially, suggesting the possible influence of other limiting factors. The substrate can also support MC3T3e1 osteogenesis. However, MJF-printed PA-12 exhibits varying ability in supporting the proliferation of different cell types, especially in subsequent passages. While L929's proliferation is comparable from passage-to-passage, MC3T3e1's growth ability is noticeably compromised. Interestingly, our results show that L929 subcultured back to polystyrene plate retains the ability to grow as robustly as those on the conventional plate, suggesting that MJF-printed PA-12 does not permanently impair cell proliferation. In addition, we have shown the successful culture of bacterial Escherichia coli on MJF-printed PA-12. Together, our study demonstrated the potential of MJF-printed PA-12 for biological applications.

Three-dimensional printing and 3D slicer powerful tools in understanding and treating neurosurgical diseases

With the development of the 3D printing industry, clinicians can research 3D printing in preoperative planning, individualized implantable materials manufacturing, and biomedical tissue modeling. Although the increased applications of 3D printing in many surgical disciplines, numerous doctors do not have the specialized range of abilities to utilize this exciting and valuable innovation. Additionally, as the applications of 3D printing technology have increased within the medical field, so have the number of printable materials and 3D printers. Therefore, clinicians need to stay up-to-date on this emerging technology for benefit. However, 3D printing technology relies heavily on 3D design. 3D Slicer can transform medical images into digital models to prepare for 3D printing. Due to most doctors lacking the technical skills to use 3D design and modeling software, we introduced the 3D Slicer to solve this problem. Our goal is to review the history of 3D printing and medical applications in this review. In addition, we summarized 3D Slicer technologies in neurosurgery. We hope this article will enable many clinicians to leverage the power of 3D printing and 3D Slicer.

3D Printed and Bioprinted Membranes and Scaffolds for the Periodontal Tissue Regeneration: A Narrative Review

Numerous technologies and materials were developed with the aim of repairing and reconstructing the tissue loss in patients with periodontitis. Periodontal guided bone regeneration (GBR) and guided tissue regeneration (GTR) involves the use of a membrane which prevents epithelial cell migration, and helps to maintain the space, creating a protected area in which tissue regeneration is favored. Over the time, manufacturing procedures of such barrier membranes followed important improvements. Three-dimensional (3D) printing technology has led to major innovations in periodontal regeneration methods, using technologies such as inkjet printing, light-assisted 3D printing or micro-extrusion. Besides the 3D printing of monophasic and multi-phasic scaffolds, bioprinting and tissue engineering have emerged as innovative technologies which can change the way we see GTR and GBR.

A full-face mask for protection against respiratory infections

BACKGROUND

Aerosols and droplets are the transmission routes of many respiratory infectious diseases. The COVID-19 management guidance recommends against the use of nebulized inhalation therapy directly in the emergency room or in an ambulance to prevent possible viral transmission. The three-dimensional printing method was used to develop an aerosol inhalation treatment mask that can potentially prevent aerosol dispersion. We conducted this utility validation study to understand the practicability of this new nebulizer mask system.

RESULTS

The fit test confirmed that the filter can efficiently remove small particles. The different locations of the mask had an excellent fit with a high pressure making a proper face seal usability. The full-face mask appeared to optimize filtration with pressure and is an example of materials that perform well for improvised respiratory protection using this design. The filtering effect test confirmed that the contamination of designated locations could be protected when using the mask with filters. As in the clinical safety test, a total of 18 participants (10 [55.6%] females; aged 33.1 ± 0.6 years) were included in the final analysis. There were no significant changes in SPO2, EtCO2, HR, SBP, DBP, and RR at the beginning, 20th, 40th, or 60th minutes of the test (all p >.05). The discomfort of wearing a mask increased slightly after time but remained within the tolerable range. The vision clarity score did not significantly change during the test. The mask also passed the breathability test.

CONCLUSION

The results of our study showed that this mask performed adequately in the fit test, the filtering test, and the clinical safety test. The application of a full-face mask with antiviral properties, together with the newly designed shape of a respirator that respects the natural curves of a human face, will facilitate the production of personal protective equipment with a highly efficient filtration system.

METHODS

We conducted three independent tests in this validation study: (1) a fit test to calculate the particle number concentration and its association with potential leakage; (2) a filtering effect test to verify the mask's ability to contain aerosol spread; and (3) a clinical safety test to examine the clinical safety, comfortableness, and visual clarity of the mask.

3D printing in Ophthalmology: From medical implants to personalised medicine

3D printing was invented thirty years ago. However, its application in healthcare became prominent only in recent years to provide solutions for drug delivery and clinical challenges, and is constantly evolving. This cost-efficient technique utilises biocompatible materials and is used to develop model implants to provide a greater understanding of human anatomy and diseases, and can be used for organ transplants, surgical planning and for the manufacturing of advanced drug delivery systems. In addition, 3D printed medical devices and implants can be customised for each patient to provide a more tailored treatment approach. The advantages and applications of 3D printing can be used to treat patients with different eye conditions, with advances in 3D bioprinting offering novel therapy applications in ophthalmology. The purpose of this review paper is to provide an in-depth understanding of the applications and advantages of 3D printing in treating different ocular conditions in the cornea, glaucoma, retina, lids and orbits.

Future foods: Design, fabrication and production through microfluidics

Many delicious foods are soft matter systems with health ingredients and unique internal structures that provide rich nutrition, unique textures, and popular flavors. Obtaining these special properties in food products usually requires specialized processes. Microfluidic technologies have been developed to physically manipulate liquids to produce a broad range of microunits, providing a suitable approach for precise fabrication of functional biomaterials with desirable interior structures in a bottom-up fashion. In this review, we present how microfluidics has been applied to produce gel-based structures and highlight their use in fabricating novel foods, focusing on, among others, cultured meat as a rapidly growing field in food industry. We first discuss the behaviors of food liquids in microchannels for fluidic structure design. Then, different types of microsized building blocks with specific geometries fabricated through microfluidics are introduced, including particles (point), fibers (line), and sheets (plane). These well-defined units can encapsulate or interact with cells, forming microtissues to construct meat products with desirable architectures. After that, we review approaches to scale up microfluidic devices for mass production of the hydrogel building blocks and highlight the challenges associated with bottom-up food production.

A Poly-(ethylene glycol)-diacrylate 3D-Printed Micro-Bioreactor for Direct Cell Biological Implant-Testing on the Developing Chicken Chorioallantois Membrane

Advancements in biomaterial manufacturing technologies calls for improved standards of fabrication and testing. Currently 3D-printable resins are being formulated which exhibit the potential to rapidly prototype biocompatible devices. For validation purposes, 3D-printed materials were subjected to a hierarchical validation onto the chorioallantoic membrane of the developing chicken, better known as the HET CAM assay. Working along these lines, prints made from poly-(ethylene glycol)-diacrylate (PEGDA), which had undergone appropriate post-print processing, outperformed other commercial resins. This material passed all tests without displaying adverse effects, as experienced with other resin types. Based on this finding, the micro bioreactors (MBR) design, first made of PDMS and that also passed with cell tests on the HET-CAM, was finally printed in PEGDA, and applied in vivo. Following this workflow shows the applicability of 3D-printable resins for biomedical device manufacturing, consents to adherence to the present standards of the 3R criteria in material research and development, and provides flexibility and fast iteration of design and test cycles for MBR adaptation and optimization.

The regulatory challenges of innovative customized combination products

Background/aims

Combination products are therapeutic and/or diagnostic products that can combine drugs and medical devices and which increasing complexity has raised new regulatory framework challenges. To reach the market, a combination product must be classified based on the principal mode of action (PMOA). However, research and technological progress has been leading to the development of novel combination products with no clearly defined PMOA, emphasizing the lack of a systematization process, thus challenging the correct classification of these products. To illustrate the regulatory challenge, two case studies are discussed: innovative combination products with PMOA that can change due to an external stimulus, specifically custom-made 3D-printed scaffolds with incorporated medicinal substances.

Methods

Data was collected through computational search engines, regulatory agencies and equally relevant associations. The analysis of the data resulted on this state-of-the-art review, a description of the decision-making process by the regulatory authorities, and case studies analysis that culminated in the proposal of a decision-tree scheme.

Findings

Current regulations do not fully address complex combination products namely personalized 3D-printed scaffolds. Two merged regulatory approaches are suggested along with the schematization of the rational assisted by a decision-tree tool.

Conclusion

Combination products have become increasingly sophisticated, which has furthered the need to develop multidisciplinary collaborations within the health sector to adapt to these innovative healthcare solutions as well as with regulators to overcome the challenges posed for their classification.

Design and Mechanical Characterization Using Digital Image Correlation of Soft Tissue-Mimicking Polymers

Present and future anatomical models for biomedical applications will need bio-mimicking three-dimensional (3D)-printed tissues. These would enable, for example, the evaluation of the quality-performance of novel devices at an intermediate step between ex-vivo and in-vivo trials. Nowadays, PolyJet technology produces anatomical models with varying levels of realism and fidelity to replicate organic tissues. These include anatomical presets set with combinations of multiple materials, transitions, and colors that vary in hardness, flexibility, and density. This study aims to mechanically characterize multi-material specimens designed and fabricated to mimic various bio-inspired hierarchical structures targeted to mimic tendons and ligaments. A Stratasys® J750™ 3D Printer was used, combining the Agilus30™ material at different hardness levels in the bio-mimicking configurations. Then, the mechanical properties of these different options were tested to evaluate their behavior under uni-axial tensile tests. Digital Image Correlation (DIC) was used to accurately quantify the specimens' large strains in a non-contact fashion. A difference in the mechanical properties according to pattern type, proposed hardness combinations, and matrix-to-fiber ratio were evidenced. The specimens V, J1, A1, and C were selected as the best for every type of pattern. Specimens V were chosen as the leading combination since they exhibited the best balance of mechanical properties with the higher values of Modulus of elasticity (2.21 ± 0.17 MPa), maximum strain (1.86 ± 0.05 mm/mm), and tensile strength at break (2.11 ± 0.13 MPa). The approach demonstrates the versatility of PolyJet technology that enables core materials to be tailored based on specific needs. These findings will allow the development of more accurate and realistic computational and 3D printed soft tissue anatomical solutions mimicking something much closer to real tissues.

Usefulness of an Additional Filter Created Using 3D Printing for Whole-Body X-ray Imaging with a Long-Length Detector

We recently developed a long-length detector that combines three detectors and successfully acquires whole-body X-ray images. Although the developed detector system can efficiently acquire whole-body images in a short time, it may show problems with diagnostic performance in some areas owing to the use of high-energy X-rays during whole-spine and long-length examinations. In particular, during examinations of relatively thin bones, such as ankles, with a long-length detector, the image quality deteriorates because of an increase in X-ray transmission. An additional filter is primarily used to address this limitation, but this approach imposes a higher load on the X-ray tube to compensate for reductions in the radiation dose and the problem of high manufacturing costs. Thus, in this study, a newly designed additional filter was fabricated using 3D printing technology to improve the applicability of the long-length detector. Whole-spine anterior–posterior (AP), lateral, and long-leg AP X-ray examinations were performed using 3D-printed additional filters composed of 14 mm thick aluminum (Al) or 14 mm thick Al + 1 mm thick copper (Cu) composite material. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and radiation dose for the acquired X-ray images were evaluated to demonstrate the usefulness of the filters. Under all X-ray inspection conditions, the most effective data were obtained when the composite additional filter based on a 14 mm thick Al + 1 mm thick Cu material was used. We confirmed that an SNR improvement of up to 46%, CNR improvement of 37%, and radiation dose reduction of 90% could be achieved in the X-ray images obtained using the composite additional filter in comparison to the images obtained with no filter. The results proved that the additional filter made with a 3D printer was effective in improving image quality and reducing the radiation dose for X-ray images obtained using a long-length detector.

Hydrogel modification of 3D printing hybrid tracheal scaffold to construct an orthotopic transplantation

OBJECTIVE

To evaluate the biological properties of modified 3D printing scaffold (PTS) and applied the hybrid graft for in situ transplantation.

METHODS

PTS was prepared via 3D printing and modified by Pluronic F-127. Biocompatibility of the scaffold was examined in vitro to ascertain its benefit in attachment and proliferation of bone marrow mesenchymal stem cells (BMSCs). Moreover, a hybrid trachea was constructed by combining the modified PTS with decellularized matrix. Finally, two animal models of in situ transplantation were established, one for repairing tracheal local window-shape defects and the other for tracheal segmental replacement.

RESULTS

The rough surface and chemical elements of the scaffold were improved after modification by Pluronic F-127. Results of BMSCs inoculation showed that the modified scaffold was beneficial to attachment and proliferation. The epithelial cells were seen crawling on and attaching to the patch, 30 days following prothetic surgery of the local tracheal defects. Furthermore, the advantages of the modified PTS and decellularized matrix were combined to generate a hybrid graft, which was subsequently applied to a tracheal segmental replacement model.

CONCLUSION

Pluronic F-127-based modification generated a PTS with excellent biocompatibility. The modified scaffold has great potential in development of future therapies for tracheal replacement and reconstruction.

Metal Ion Emission and Corrosion Resistance of 3D-Printed Dental Alloy

Background: Prosthetic rehabilitation requires application of materials with different chemical, mechanical and biological properties which must provide longevity, esthetics, and safe use. Corrosion resistance and metal ion emission are the major factors defining biocompatibility of base dental alloys. Digitalization in Dentistry leads to development of new materials suitable for CAD/CAM technologies. Cobalt-chromium powder alloys are used for additive manufacturing of PFM crowns. The aim of this study is to evaluate corrosion resistance and metal ion emission of Cobalt-chromium dental alloy for 3D printing. Materials and methods: 35 metal copings were designed using digital files of intraoral scans of 35 patients. CoCr dental alloy EOS CobaltChrome SP2 (EOS, Germany) was used to produce the copings by DMLS (direct laser metal sintering). Tests for presence of free Cobalt ions were conducted at several stages of the production process. Open circuit potential measurements were conducted 2 hours, 24 hours, and 7 days after placing the copings in artificial saliva. Metal ion emission was assessed by inductively coupled plasma mass spectrometry (ICP–MS) after 24 hour- and 7 day-period of stay in the solution. Results: Tests for free Cobalt ions were positive at all stages during production of the metal copings. Eocp measurements showed high corrosion resistance which increased in time. ICP-MS showed significantly higher amount of cobalt and chromium ions after 7-day period of stay compared to 24-hour period. Conclusion: Studied alloy showed high corrosion resistance at in vitro conditions. Detected ion emission requires further investigations on the biological properties.

MHM bracket design on the path of Dr Andrews of true straight wire technique, prototype study design

OBJECTIVE:

The authors invented an innovation in the bracket design; that targeted to fulfill the aim of Dr. Andrews for a true straight wire technique.

MATERIALS AND METHODS:

The use of the ball and socket design together with the ability to relocate the position of the slot in three dimensions enhances the control and precision of individual teeth.

RESULTS:

The revolutionary bracket eliminated any wire bending in the initial, intermediate or finishing stages of fixed orthodontic treatment. This was achieved together with complete 3D control on individual teeth positions to achieve the finest occlusion for individual patients.

CONCLUSIONS:

That system allowed for a true straight wire mechanics with no wire bending. The design could be used labially or lingually without the need of indirect bonding techniques. Additionally, any adjustments could be performed intraorally with simple pressure.

How 3D Printing Is Reshaping Translational Research

"Translational Research" has traditionally been defined as taking basic scientific findings and developing new diagnostic tools, drugs, devices and treatment options for patients, that are translated into practice, reach the people and populations for whom they are intended and are implemented correctly. The implication is of a unidirectional flow from "the bench to bedside". The rapidly emergent field of additive manufacturing (3D printing) is contributing to a major shift in translational medical research. This includes the concept of bidirectional or reverse translation, early collaboration between clinicians, bio-engineers and basic scientists, and an increasingly entrepreneurial mindset. This coincides with, and is strongly complemented by, the rise of systems biology. The rapid pace at which this type of translational research can occur brings a variety of potential pitfalls and ethical concerns. Regulation surrounding implantable medical devices is struggling to keep up. 3D printing has opened the way for personalization which can make clinical outcomes hard to assess and risks putting the individual before the community. In some instances, novelty and hype has led to loss of transparency of outcomes with dire consequence. Collaboration with commercial partners has potential for conflict of interest. Nevertheless, 3D printing has dramatically changed the landscape of translational research. With early recognition and management of the potential risks, the benefits of reshaping the approach to translational research are enormous. This impact will extend into many other areas of biomedical research, re-establishing that science is more than a body of research. It is a way of thinking.

Three-Dimensional Printing of Medical Devices Used Directly to Treat Patients: A Systematic Review

Until recently, three-dimensional (3D) printing/additive manufacturing has not been used extensively to create medical devices intended for actual clinical use, primarily on patient safety and regulatory grounds. However, in recent years there have been advances in materials, printers, and experience, leading to increased clinical use. The aim of this study was to perform a structured systematic review of 3D-printed medical devices used directly in patient treatment. A search of 13 databases was performed to identify studies of 3D-printed medical devices, detailing fabrication technology and materials employed, clinical application, and clinical outcome. One hundred and ten papers describing one hundred and forty medical devices were identified and analyzed. A considerable increase was identified in the use of 3D printing to produce medical devices directly for clinical use in the past 3 years. This is dominated by printing of patient-specific implants and surgical guides for use in orthopedics and orthopedic oncology, but there is a trend of increased use across other clinical specialties. The prevailing material/3D-printing technology used were titanium alloy/electron beam melting for implants, and polyamide/selective laser sintering or polylactic acid/fused deposition modeling for surgical guides and instruments. A detailed analysis across medical applications by technology and materials is provided, as well as a commentary regarding regulatory aspects. In general, there is growing familiarity with, and acceptance of, 3D printing in clinical use.