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Background: Fabricating clear aligners by thermoforming three‐dimensional printed dental models requires a high degree of accuracy. It is unknown whether model thickness affects the accuracy when used to thermoform aligners. Purpose: This research utilizes three‐dimensional printed models made with differing wall thicknesses to determine its effect on their ability to withstand deformation during aligner fabrication. Methods: A total of 50 models of different wall thickness (10 each of 0.5, 1.0, 1.5, 2.0 mm, and solid) were printed using model resin (Model V2, Formlabs) on a low‐force stereolithography printer (Form 3B, Formlabs). Aligners were then fabricated using a thermal pressure forming machine (Biostar V, Great Lakes Dental Technologies) utilizing 25 s cycles to adapt 0.030″ acrylic sheets (Invisacryl, Great Lakes Dental Technologies), then removed from the models and sprayed with a contrast powder (Optispray, Dentsply Sirona) to aid in scanning with an intraoral scanner (CEREC Primescan, Dentsply Sirona). Each aligner's data was then compared to the original file used for printing with 3D comparison software (Geomagic Control X, 3D Systems). Results: The results show model thickness greater than or equal to 2.0 mm produced clinically acceptable results within the margin of error (0.3 mm). A total of 0.5 mm thickness failed to withstand thermal forming in 4 of the 10 trials. A total of 0.5 mm produced 27.56% of results in tolerance, 1.0 mm produced 75.66% of results in tolerance, 1.5 mm had 80.38% of results in tolerance, 86.82% of 2 mm models were in tolerance, and solid had 96.45% of results in tolerance. Conclusion: Hollow models of thicknesses 2.0 mm and solid models produced clinically acceptable aligners while utilizing less resin per unit compared to solid models, thus being more cost effective, time efficient and eco‐friendly. Therefore, a recommendation can be made to print hollow models with a shell thickness of greater than 2.0 mm for aligner fabrication. [ABSTRACT FROM AUTHOR]

Objective: To assess the preliminary effectiveness of three-dimensional printed orthoses compared with conventionally custom-fabricated orthoses in persons with chronic hand conditions on performance of daily activities, hand function, quality of life, satisfaction, and production time and costs. Design: Interventional feasibility study. Subjects: Chronic hand orthotic users (n = 21). Methods: Participants received a new three-dimensional printed orthosis according to the same type as their current orthosis, which served as the control condition. Primary outcome was performance of daily activities (Patient-Reported Outcomes Measurement Information System–Upper Extremity; Michigan Hand Questionnaire). Secondary outcomes were hand function, quality of life, and satisfaction. Furthermore, production time and costs were recorded. Results: At 4 months’ follow-up, no significant differences were found between three-dimensional printed orthoses and participants’ existing conventional orthoses on activity performance, hand function, and quality of life. Satisfaction with the three-dimensional printed orthosis was significantly higher and the production time and costs for three-dimensional printed orthoses were significantly lower compared with conventional orthoses. The three-dimensional printed orthosis was preferred by 79% of the participants. Conclusions: This feasibility study in chronic hand conditions suggests that three-dimensional printed orthoses are similar to conventional orthoses in terms of activity performance, hand function, and quality of life. Satisfaction, and production time and costs favoured the three-dimensional printed hand orthoses.

Abstract Objective The interest in using 3D printing in the healthcare field has grown over the years, given its advantages and potential in the rapid manufacturing of personalized devices and implants with complex geometries. Thus, the aim of the present study was to compare the mechanical fixation behavior of a 3D-printed interference screw, produced by fused deposition modeling of polylactic acid (PLA) filament, with that of a titanium interference screw. Methods Eight deep flexor porcine tendons, approximately 8 mm wide and 9 cm long, were used as graft and fixed to a 40 pounds-per-cubic-foot (PCF) polyurethane block at each of its extremities. One group was fixed only with titanium interference screws (group 1) and the other only with 3D-printed PLA screws (BR 20 2021 018283-6 U2) (group 2). The tests were conducted using an EMIC DL 10000 electromechanical universal testing machine in axial traction mode. Results Group 1 (titanium) obtained peak force of 200 ± 7 N, with mean graft deformation of 8 ± 2 mm, and group 2 (PLA) obtained peak force of 300 ± 30 N, and mean graft deformation of 7 ± 3 mm. Both the titanium and PLA screws provided good graft fixation in the polyurethane block, with no slippage or apparent deformation. In all the samples, the test culminated in graft rupture, with around 20 mm of deformation in relation to the initial length. Conclusion The 3D-printed PLA screw provided good fixation, similar to that of its titanium counterpart, producing satisfactory and promising results.

Objective: To determine the effect of common beverages and accelerated aging on the colour stability of filled resins, which could potentially be used for fabrication of 3D‐printed orthodontic brackets. Materials and Methods: GR‐17.1 (shades A1, A2, and A3), and GR‐10 Guide resins (pro3dure medical, Eden Prairie, MN) were printed on an Asiga MAX UV printer into discs 2 mm thick, with a diameter of 10 mm, and then post‐print processed as per manufacturer's instructions. Discs were immersed in 5 mL of coffee, tea, red wine, or distilled water for 7 days. Another group was subjected to accelerated aging in accordance with ISO Standard 4892‐2. Ten samples were produced per resin, per treatment condition. Colour measurements were taken on the discs before and after treatment using a spectrophotometer against white and black reference tiles to assess colour and translucency differences with the CIEDE2000 colour difference formula. Results: While initial colour of the printed resin discs was acceptable, all resin groups underwent significant colour change during the experiment. Red wine and coffee produced the greatest colour and translucency change, followed by tea, with accelerated aging producing the least change in colour and translucency. Conclusion: The 3D‐printed resins tested underwent significant changes in colour and translucency following exposure to endogenous and exogenous sources of staining, which may affect their acceptability for fabrication of aesthetic orthodontic brackets. [ABSTRACT FROM AUTHOR]

Objectives: Three-dimensional (3D) printing has been increasingly used to create accurate patient-specific 3D-printed models from medical imaging data. We aimed to evaluate the utility of 3D-printed models in the localization and understanding of pancreatic cancer for surgeons before pancreatic surgery. Methods: Between March and September 2021, we prospectively enrolled 10 patients with suspected pancreatic cancer who were scheduled for surgery. We created an individualized 3D-printed model from preoperative CT images. Six surgeons (three staff and three residents) evaluated the CT images before and after the presentation of the 3D-printed model using a 7-item questionnaire (understanding of anatomy and pancreatic cancer [Q1–4], preoperative planning [Q5], and education for trainees or patients [Q6–7]) on a 5-point scale. Survey scores on Q1–5 before and after the presentation of the 3D-printed model were compared. Q6–7 assessed the 3D-printed model's effects on education compared to CT. Subgroup analysis was performed between staff and residents. Results: After the 3D-printed model presentation, survey scores improved in all five questions (before 3.90 vs. after 4.56, p < 0.001), with a mean improvement of 0.57‒0.93. Staff and resident scores improved after a 3D-printed model presentation (p < 0.05), except for Q4 in the resident group. The mean difference was higher among the staff than among the residents (staff: 0.50‒0.97 vs. residents: 0.27‒0.90). The scores of the 3D-printed model for education were high (trainees: 4.47 vs. patients: 4.60) compared to CT. Conclusion: The 3D-printed model of pancreatic cancer improved surgeons' understanding of individual patients' pancreatic cancer and surgical planning. Clinical relevance statement: The 3D-printed model of pancreatic cancer can be created using a preoperative CT image, which not only assists surgeons in surgical planning but also serves as a valuable educational resource for patients and students. Key Points: • A personalized 3D-printed pancreatic cancer model provides more intuitive information than CT, allowing surgeons to better visualize the tumor's location and relationship to neighboring organs. • In particular, the survey score was higher among staff who performed the surgery than among residents. • Individual patient pancreatic cancer models have the potential to be used for personalized patient education as well as resident education. [ABSTRACT FROM AUTHOR]

Abstract Background Fabricating clear aligners by thermoforming three‐dimensional printed dental models requires a high degree of accuracy. It is unknown whether model thickness affects the accuracy when used to thermoform aligners. Purpose This research utilizes three‐dimensional printed models made with differing wall thicknesses to determine its effect on their ability to withstand deformation during aligner fabrication. Methods A total of 50 models of different wall thickness (10 each of 0.5, 1.0, 1.5, 2.0 mm, and solid) were printed using model resin (Model V2, Formlabs) on a low‐force stereolithography printer (Form 3B, Formlabs). Aligners were then fabricated using a thermal pressure forming machine (Biostar V, Great Lakes Dental Technologies) utilizing 25 s cycles to adapt 0.030″ acrylic sheets (Invisacryl, Great Lakes Dental Technologies), then removed from the models and sprayed with a contrast powder (Optispray, Dentsply Sirona) to aid in scanning with an intraoral scanner (CEREC Primescan, Dentsply Sirona). Each aligner's data was then compared to the original file used for printing with 3D comparison software (Geomagic Control X, 3D Systems). Results The results show model thickness greater than or equal to 2.0 mm produced clinically acceptable results within the margin of error (0.3 mm). A total of 0.5 mm thickness failed to withstand thermal forming in 4 of the 10 trials. A total of 0.5 mm produced 27.56% of results in tolerance, 1.0 mm produced 75.66% of results in tolerance, 1.5 mm had 80.38% of results in tolerance, 86.82% of 2 mm models were in tolerance, and solid had 96.45% of results in tolerance. Conclusion Hollow models of thicknesses 2.0 mm and solid models produced clinically acceptable aligners while utilizing less resin per unit compared to solid models, thus being more cost effective, time efficient and eco‐friendly. Therefore, a recommendation can be made to print hollow models with a shell thickness of greater than 2.0 mm for aligner fabrication.

Abstract Objective Due to the popularity of 3D technology, surgeons can create specific surgical guides and sterilize them in their institutions. The aim of the present study is to compare the efficacy of the autoclave and ethylene oxide (EO) sterilization methods for objects produced by 3D printing with polylactic acid (PLA) material. Methods Forty cubic-shaped objects were printed with PLA material. Twenty were solid and 20 were hollow (printed with little internal filling). Twenty objects (10 solid and 10 hollow) were sterilized in autoclave, forming Group 1. The others (10 solid and 10 hollow) were sterilized in EO, composing Group 2. After sterilization, they were stored and referred to culture. Hollow objects of both groups were broken during sowing, communicating the dead space with the culture medium. The results obtained were statistically analyzed (Fisher exact test and residue analysis). Results In group 1 (autoclave), there was bacterial growth in 50% of solid objects and in 30% of hollow objects. In group 2 (EO), growth occurred in 20% of hollow objects, with no bacterial growth in solid objects (100% of negative samples). The bacteria isolated in the positive cases was non-coagulase-producing Staphylococcus Gram positive. Conclusions Sterilization by both autoclave and EO was not effective for hollow printed objects. Solid objects sterilized by autoclave did not demonstrate 100% of negative samples and were not safe in the present assay. Complete absence of contamination occurred only with solid objects sterilized by EO, which is the combination recommended by the authors.

Abstract Objective To evaluate a proposed three-dimensional (3D) printing process of a biomodel developed with the aid of fused deposition modeling (FDM) technology based on computed tomography (CT) scans of an individual with nonunion of a coronal femoral condyle fracture (Hoffa’s fracture). Materials and Methods Thus, we used CT scans, which enable the evaluation of the 3D volumetric reconstruction of the anatomical model, as well as of the architecture and bone geometry of sites with complex anatomy, such as the joints. In addition, it enables the development of the virtual surgical planning (VSP) in a computer-aided design (CAD) software. This technology makes it possible to print full-scale anatomical models that can be used in surgical simulations for training and in the choice of the best placement of the implant according to the VSP. In the radiographic evaluation of the osteosynthesis of the Hoffa’s fracture nonunion, we assessed the position of the implant in the 3D-printed anatomical model and in the patient’s knee. Results The 3D-printed anatomical model showed geometric and morphological characteristics similar to those of the actual bone. The position of the implants in relation to the nonunion line and anatomical landmarks showed great accuracy in the comparison of the patient’s knee with the 3D-printed anatomical model. Conclusion The use of the virtual anatomical model and the 3D-printed anatomical model with the additive manufacturing (AM) technology proved to be effective and useful in planning and performing the surgical treatment of Hoffa’s fracture nonunion. Thus, it showed great accuracy in the reproducibility of the virtual surgical planning and the 3D-printed anatomical model.

ABSTRACT Purpose: To evaluate the gain of microsurgical skills and competencies by urology residents, using low-fidelity experimental models. Methods: The study involved the use of training boards, together with a low-fidelity microsurgery simulator, developed using a 3D printer. The model consists in two silicone tubes, coated with a resin, measuring 10 cm in length and with internal and external diameters of 0.5 and 1.5 mm. The support for the ducts is composed by a small box, developed with polylactic acid. The evaluation of the gain of skills and competencies in microsurgery occurred throughout a training course consisting of five training sessions. The first sessions (S1-S4) took place at weekly intervals and the last session (S5) was performed three months after S4. During sessions, were analyzed: the speed of performing microsurgical sutures in the pre and post-training and the performance of each resident through the Objective Structure Assessment of Technical Skill (OSATS) and Student Satisfaction Self-Confidence tools in Learning (SSSCL). Results: There was a decrease in the time needed to perform the anastomosis (p=0.0019), as well as a progressive increase in the score in the OSATS over during sessions S1 to S4. At S5, there was a slightly decrease in performance (p

Abstract Background Three-dimensional (3D) printing is a novel innovation in the field of craniomaxillofacial surgery, however, a lack of evidence exists related to the comparison of the trueness of skull models fabricated using different technology-based printers belonging to different cost segments. Methods A study was performed to investigate the trueness of cone-beam computed tomography-derived skull models fabricated using different technology based on low-, medium-, and high-cost 3D printers. Following the segmentation of a patient’s skull, the model was printed by: (i) a low-cost fused filament fabrication printer; (ii) a medium-cost stereolithography printer; and (iii) a high-cost material jetting printer. The fabricated models were later scanned by industrial computed tomography and superimposed onto the original reference virtual model by applying surface-based registration. A part comparison color-coded analysis was conducted for assessing the difference between the reference and scanned models. A one-way analysis of variance (ANOVA) with Bonferroni correction was applied for statistical analysis. Results The model printed with the low-cost fused filament fabrication printer showed the highest mean absolute error ( $$1.33\pm 0.24 \text{mm}$$ 1.33 ± 0.24 mm ), whereas both medium-cost stereolithography-based and the high-cost material jetting models had an overall similar dimensional error of $$0.07\pm 0.03 \text{mm}$$ 0.07 ± 0.03 mm and $$0.07\pm 0.01 \text{mm}$$ 0.07 ± 0.01 mm , respectively. Overall, the models printed with medium- and high-cost printers showed a significantly ( $$p

Background: Three-dimensional (3D) printing is a novel innovation in the field of craniomaxillofacial surgery, however, a lack of evidence exists related to the comparison of the trueness of skull models fabricated using different technology-based printers belonging to different cost segments. Methods: A study was performed to investigate the trueness of cone-beam computed tomography-derived skull models fabricated using different technology based on low-, medium-, and high-cost 3D printers. Following the segmentation of a patient's skull, the model was printed by: (i) a low-cost fused filament fabrication printer; (ii) a medium-cost stereolithography printer; and (iii) a high-cost material jetting printer. The fabricated models were later scanned by industrial computed tomography and superimposed onto the original reference virtual model by applying surface-based registration. A part comparison color-coded analysis was conducted for assessing the difference between the reference and scanned models. A one-way analysis of variance (ANOVA) with Bonferroni correction was applied for statistical analysis. Results: The model printed with the low-cost fused filament fabrication printer showed the highest mean absolute error ( 1.33 ± 0.24 mm ), whereas both medium-cost stereolithography-based and the high-cost material jetting models had an overall similar dimensional error of 0.07 ± 0.03 mm and 0.07 ± 0.01 mm , respectively. Overall, the models printed with medium- and high-cost printers showed a significantly ( p < 0.01 ) lower error compared to the low-cost printer. Conclusions: Both stereolithography and material jetting based printers, belonging to the medium- and high-cost market segment, were able to replicate the skeletal anatomy with optimal trueness, which might be suitable for patient-specific treatment planning tasks in craniomaxillofacial surgery. In contrast, the low-cost fused filament fabrication printer could serve as a cost-effective alternative for anatomical education, and/or patient communication. [ABSTRACT FROM AUTHOR]

Brachytherapy is an essential part of radical radiotherapy of cervical cancer. However, traditional brachytherapy applicators are difficult to be placed, cannot be adapted to individualized local lesions, and have unsatisfactory dose distribution for some patients with recurrent postoperative stumps or eccentric or large cervical cancer, which then affects the efficacy and prognosis. Personalized radiotherapy products can be designed for each patient by utilizing 3D printing technology. Combination of 3D printing technology and brachytherapy can effectively improve accuracy of radiotherapy. The application of 3D printing technology in cervical cancer brachytherapy mainly includes the construction of cervical cancer model to preoperative planning and display tumor shape as well as anatomic relationship between tumor and surrounding tissues. It also includes the production of personalized applicator to reduce the occurrence of air gaps to achieve precise dose distribution. In addition, the design of parallel/oblique needle channel applicator and the optimization of needle channel and target dose distribution are also included. Applications of 3D printing technology in brachytherapy of cervical cancer have been summarized in the afore-mentioned areas. At the same time, the challenges in the development of 3D printing materials, system establishment and image guidance have been discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose: This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs. Methods: In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate–PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure. Results: All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups. Conclusions: The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.

Abstract The formation of biofilm on denture bases is a recurrent clinical problem that favors the development of denture stomatitis. The effectiveness of a hygiene protocol in a 3D-printed denture base resin is still uncertain. Objective To evaluate of the effectiveness of immersion, associated or not with brushing in a soap solution, on the biofilm control of a 3D-printed denture base resin. Methodology Specimens of denture base resins [Cosmos Denture (COS) and Classico (CLA/control)] were contaminated in vitro with Candida albicans and immersed in sodium hypochlorite 0.25% (SH, alkaline peroxide) AP, chlorhexidine digluconate 2% (CD or PBS-Control), associated or not with brushing with 0.78% Lifebuoy soap. Roughness was evaluated before and after brushing and immersion. The effectiveness of the protocols was assessed by CFU/mL, cellular metabolism (XTT), scanning electron microscopy (SEM), and confocal scanning laser microscopy. Data were analyzed by T student, ANOVA/Welch, and Tukey/Gomes–Howell pos-hoc tests (α = 0.05). Results CLA showed greater roughness than COS. CFU/mL and XTT were higher in COS resin with a higher hyphae formation. Immersion in SH and CD eliminated CFU/mL and reduced XTT for both resins, associated or not with brushing. AP reduced CFU/mL only when associated with brushing. Conclusions The biofilm on the 3D-printed resin was thicker and presumably more pathogenic, regardless of its smoother surface. Immersions in SH 0.25% and CD 2% are effective hygiene protocols for both resins, associated or not with brushing. AP should be recommended when associated with brushing with a Lifebuoy 0.78% solution.

Flapless and fully guided implant placement has the potential to maximize efficacy outcomes and at the same time to minimize surgical invasiveness. The aim of the current systematic review was to answer the following PICO question: "In adult human subjects undergoing dental implant placement (P), is minimally invasive flapless computer‐aided fully guided (either dynamic or static computer‐aided implant placement (sCAIP)) (I) superior to flapped conventional (free‐handed implant placement (FHIP) or cast‐based/drill partially guided implant placement (dPGIP)) surgery (C), in terms of efficacy, patient morbidity, long‐term prognosis, and costs (O)?" Randomized clinical trials (RCTs) fulfilling specific inclusion criteria established to answer the PICO question were included. Two review authors independently searched for eligible studies, screened the titles and abstracts, performed full‐text analysis, extracted the data from the published reports, and performed the risk of bias assessment. In cases of disagreement, a third review author took the final decision during ad hoc consensus meetings. The study results were summarized using random effects meta‐analyses, which were based (wherever possible) on individual patient data (IPD). A total of 10 manuscripts reporting on five RCTs, involving a total of 124 participants and 449 implants, and comparing flapless sCAIP with flapped FHIP/cast‐based partially guided implant placement (cPGIP), were included. There was no RCT analyzing flapless dynamic computer‐aided implant placement (dCAIP) or flapped dPGIP. Intergroup meta‐analyses indicated less depth deviation (difference in means (MD) = −0.28 mm; 95% confidence interval (CI): −0.59 to 0.03; moderate certainty), angular deviation (MD = −3.88 degrees; 95% CI: −7.00 to −0.77; high certainty), coronal (MD = −0.6 mm; 95% CI: −1.21 to 0.01; low certainty) and apical (MD = −0.75 mm; 95% CI: −1.43 to −0.07; moderate certainty) three‐dimensional bodily deviations, postoperative pain (MD = −17.09 mm on the visual analogue scale (VAS); 95% CI: −33.38 to −0.80; low certainty), postoperative swelling (MD = −6.59 mm on the VAS; 95% CI: −19.03 to 5.85; very low certainty), intraoperative discomfort (MD = −9.36 mm on the VAS; 95% CI: −17.10 to −1.61) and surgery duration (MD = −24.28 minutes; 95% CI: −28.62 to −19.95) in flapless sCAIP than in flapped FHIP/cPGIP. Despite being more accurate than flapped FHIP/cPGIP, flapless sCAIP still resulted in deviations with respect to the planned position (intragroup meta‐analytic means: 0.76 mm in depth, 2.57 degrees in angular, 1.43 mm in coronal, and 1.68 in apical three‐dimensional bodily position). Moreover, flapless sCAIP presented a 12% group‐specific intraoperative complication rate, resulting in an inability to place the implant with this protocol in 7% of cases. Evidence regarding more clinically relevant outcomes of efficacy (implant survival and success, prosthetically and biologically correct positioning), long‐term prognosis, and costs, is currently scarce. When the objective is to guarantee minimal invasiveness at implant placement, clinicians could consider the use of flapless sCAIP. A proper case selection and consideration of a safety margin are, however, suggested. [ABSTRACT FROM AUTHOR]

Abstract Accurate and reproducible analysis of murine small and large intestinal tissue is key for preclinical models involving intestinal pathology. Currently, there is no easily accessible, standardized method that allows researchers of different skill levels to consistently dissect intestines in a time‐efficient manner. Here, we describe the design and use of the 3D‐printed “Mouse Intestinal Slicing Tool” (MIST), which can be used to longitudinally dissect murine intestines for further analysis. We benchmarked the MIST against a commonly used procedure involving scissors to make a longitudinal cut along the intestines. Use of the MIST halved the time per mouse to prepare the intestines and outperformed alternative methods in smoothness of the cutting edge and overall reproducibility. By sharing the plans for printing the MIST, we hope to contribute a uniformly applicable method for saving time and increasing consistency in studies of the mouse gastrointestinal tract.

In nature, basically 2 types of myocardial vascular patterns exist: the sinusoidal and the coronary type. In the sinusoidal type, the sinusoid is completely fed by blood coming directly from the ventricle through a spongy sinusoidal network. This pattern is found in cold-blooded animals and in the early embryologic development of human (warm-blooded) hearts. A 61-year-old man with atrial fibrillation developed severe tachymyopathy with a severely reduced left-ventricular ejection fraction (LVEF) of 20%. The patient had no history of prior heart surgery or other cardiac interventions. He was referred for a computed tomography (CT) scan for assessment of pulmonary vein anatomy prior to their isolation. Incidentally, a focal myocardial defect of the midventricular infero-septal wall with tail-like extension into the right ventricular cavity was detected. In a cardiac magnetic resonance (CMR) scan there was no evidence of a myocardial infarction or fibrosis. In the absence of a ventricular septal defect by CT, CMR and echocardiography the diagnosis of a persistent myocardial sinusoid was evident. In this case, we used state-of-the art methods for pathology visualization, illustrating the effectiveness of CT and CMR in the precise detection and differential diagnosis of myocardial anomalies including a multi-coloured 3D-printed model that may further enhance visuospatial appreciation of those anomalies.

Abstract Background Immediate loading of implant-supported full-arch rehabilitations has become routine practice when treating edentulous patients. The combination of static computer-aided implant surgery (s-CAIS) and digital prosthetic workflow could eliminate several treatment steps and facilitate prostheses delivery. The aim of this study is to evaluate the 1-year results of digitally prefabricated polymethyl methacrylate (PMMA) provisional prostheses without a cast for full-arch computer-assisted immediate loading. Materials and methods A digital pre-operative treatment planning was realized for all patients: dental implants and screw-retained abutments were selected in the planning software and two surgical templates were fabricated for each patient. The first template was mucosa or teeth-supported to drill the holes for fixating pins, while the second template was placed after raising a full-thickness flap and was supported by pins as well as soft or hard tissue distal support. Furthermore, based on the surgical planning, interim prostheses were digitally designed and milled of PMMA resin blocks with subsequent pink resin veneering. Osteotomies and implant placement were performed through the surgical guides and all implants were immediately loaded with prefabricated full-arch interim prostheses directly connected to titanium copings with a flowable resin. Results A total of 55 dental implants were placed in ten patients. In all cases, interim prostheses allowed the insertion of titanium copings without the need of access hole enlargement or adaptation. All the prostheses had 1 year of functional loading to simulate the long provisional phase. No screw loosening occurred at the first removal of the prostheses after implant osseointegration. No fracture occurred during the whole period. After 1 year, the mean marginal bone loss level was 0.37 ± 0.06 mm, while the implant survival rate was 98.18% (n=54/55), with just one implant failing but not affecting final prosthesis delivery to the patient. Conclusions Within the limitations of the present study, the authors concluded that digitally prefabricated provisional prostheses for full-arch immediate loading with s-CAIS could be a valid alternative treatment modality. Milled PMMA restorations proved to be durable enough during the long provisional phase, without prosthetic complications.

Abstract Background Material extrusion is used to 3D print anatomic models and guides. Sterilization is required if a 3D printed part touches the patient during an intervention. Vaporized Hydrogen Peroxide (VHP) is one method of sterilization. There are four factors to consider when sterilizing an anatomic model or guide: sterility, biocompatibility, mechanical properties, and geometric fidelity. This project focuses on geometric fidelity for material extrusion of one polymer acrylonitrile butadiene styrene (ABS) using VHP. Methods De-identified computed tomography (CT) image data from 16 patients was segmented using Mimics Innovation Suite (Materialise NV, Leuven, Belgium). Eight patients had maxillary and mandibular defects depicted with the anatomic models, and eight had mandibular defects for the anatomic guides. Anatomic models and guides designed from the surfaces of CT scan reconstruction and segementation were 3D printed in medical-grade acrylonitrile butadiene styrene (ABS) material extrusion. The 16 parts underwent low-temperature sterilization with VHP. The dimensional error was estimated after sterilization by comparing scanned images of the 3D printed parts. Results The average of the estimated mean differences between the printed pieces before and after sterilization were − 0,011 ± 0,252 mm (95%CI − 0,011; − 0,010) for the models and 0,003 ± 0,057 mm (95%CI 0,002; 0,003) for the guides. Regarding the dimensional error of the sterilized parts compared to the original design, the estimated mean differences were − 0,082 ± 0,626 mm (95%CI − 0,083; − 0,081) for the models and 0,126 ± 0,205 mm (95%CI 0,126, 0,127) for the guides. Conclusion This project tested and verified dimensional stability, one of the four prerequisites for introducing vaporized hydrogen peroxide into 3D printing of anatomic models and guides; the 3D printed parts maintained dimensional stability after sterilization.

In this study, compact 3D-printed carbon black (CB) electrodes were manufactured for using in folic acid (FA) analysis in fruit samples. Before application in FA analysis, the electrode surfaces were characterized by high-resolution scanning electron microscopy and voltammetry using well-known redox probes. Square wave voltammetric study presented linear responses in the range between 10 and 200 µmol/L (R 2  > 0.99), exhibited a suitable detection limit (LOD) of ∼ 5.1 µmol/L and acceptable performance in terms of reproducibility and anti-interference experiments. The analysis of FA in four different food samples using the proposed method agreed statistically with a comparative technique based on spectrophotometric measurements. Moreover, results from photostability experiments indicated that FA can be degraded after 5 and 20 min of UV exposure. These results successfully demonstrated the analytical feasibility of the 3D-printed electrodes as sensing material and for monitoring the photostability of FA in different fruit matrices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study investigated particle and volatile organic compound (VOC) emission rates (ER) from 3D pens, which are increasingly popular in children's toys. Nine filaments and two 3D pens were evaluated using a flow tunnel, a scanning mobility particle sizer, a proton-transfer-reaction time-of-flight mass spectrometer for particles, and a thermal desorption-gas chromatography-mass spectrometer for VOCs. Results showed that the ERs varied with the pen type, filament, and brand. The particle ER was highest for acrylonitrile butadiene styrene (ABS), followed by polylactic acid (PLA) and polycaprolactone (PCL). Notably, ERs of 83 % and 33 % of ABS and PLA filaments exceeded the maximum allowable particle ER (MAER; 5 × 10 9 particles/min) for 3D printers but were lower than the VOC MAER (173 μg/min in the office). Different filaments emitted diverse VOCs; ABS emitted styrene and benzene, PLA emitted lactide, and PCL emitted phenol. While particle ERs from 3D pens were comparable to those from printers, the total VOC ERs from 3D pens were slightly lower. Caution is warranted when using 3D pens because of potential health risks, especially their prolonged use, proximity to the breathing zone, and usage by children. This study highlights the need for considering particles and VOCs when assessing the safety of 3D pens, emphasizing awareness of potential hazards, particularly in child-oriented settings., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Chungsik Yoon reports financial support was provided by Korea Environmental Industry and Technology Institute. Chungsik Yoon reports financial support was provided by the Ministry of Education of the Republic of Korea and the National Research Foundation of Korea. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The direct ink writing technique used in 3D printing technology is generally applied to designing biomedical hydrogels. Herein, we proposed a strategy for preparing all-chitin-based inks for wound dressing via direct ink writing technique. The β-chitin nanofibers (MACNF) with a high aspect ratio were applied as a nanofiller to modulate the rheological properties of the alkaline dissolved chitin solution. The printing fidelity significantly depends on the MACNF introduction amount to the composite ink. 5-10 wt% MACNF ratio showed superior printing performance. The printed scaffold showed a uniform micron-sized pore structure and a woven network of nanofibers. Due to the good biocompatibility of chitin and the stereoscopic spatial skeleton, this scaffold showed excellent performance as a wound dressing, which can promote cell proliferation, collagen deposition and the angiogenesis of wounds, demonstrating its potential in biomedical applications. This approach successfully balanced the chitinous printability and biofunctions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Herein, we proposed dry heat treatment (DHT) as a pre-treatment method for modifying printed materials, with a particular focus on its application in the control of starch-lipid interactions during hot-extrusion 3D printing (HE-3DP). The results showed that pre-DHT could promote the complexation of wheat starch (WS) and oleic acid (OA)/corn oil (CO) during HE-3DP and thus increase the resistant starch (RS) content. From the structural perspectives, pre-DHT could break starch molecular chains into lower relative molecular weight which enhanced the starch-lipids hydrophobic interactions to form the V-type crystalline structure during HE-3DP. Notably, pre-DHT could also induce the formation of complexed structure which was maintained during HE-3DP. Compared with CO, OA with linear hydrophobic chains was easier to enter the spiral cavity of starch to form more ordered structures, resulting in higher RS content of 27.48 %. Overall, the results could provide basic data for designing nutritional starchy food systems by HE-3DP., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study focuses on the combination of three-dimensional printing (3DP) and amorphous solid dispersion (ASD) technologies for the manufacturing of gastroretentive floating tablets. Employing hot melt extrusion (HME) and fused deposition modeling (FDM), the study investigates the development of drug-loaded filaments and 3D printed (3DP) tablets containing felodipine as model drug and hydroxypropyl methylcellulose (HPMC) as the polymeric carrier. Prior to fabrication, solubility parameter estimation and molecular dynamics simulations were applied to predict drug-polymer interactions, which are crucial for ASD formation. Physical bulk and surface characterization complemented the quality control of both drug-loaded filaments and 3DP tablets. The analysis confirmed a successful amorphous dispersion of felodipine within the polymeric matrix. Furthermore, the low infill percentage and enclosed design of the 3DP tablet allowed for obtaining low-density systems. This structure resulted in buoyancy during the entire drug release process until a complete dissolution of the 3DP tablets (more than 8 h) was attained. The particular design made it possible for a single polymer to achieve a zero-order controlled release of the drug, which is considered the ideal kinetics for a gastroretentive system. Accordingly, this study can be seen as an advancement in ASD formulation for 3DP technology within pharmaceutics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The application of three-dimensional printing (3DP) in the pharmaceutical industry brings a broad spectrum of benefits to patients by addressing individual needs and improve treatment success. This study investigates the sustained release properties of 3DP tablets containing Theophylline (TPH), which is commonly used to treat respiratory diseases and recently having a comeback due to its potential in the treatment of conditions like Covid-19. Since TPH is a narrow therapeutic window (NTW) drug with serious side effects in the event of overdose, the release properties must be observed particularly closely. We employed a state-of-the-art single screw extrusion 3D printer, which is fed with granules containing the drug. By employing a Taguchi orthogonal array design of experiments (DOE), tablet design parameters and factor related process stability were sought to be evaluated fundamentally. Following this, examinations regarding tailored TPH dosages were undertaken and a relationship between the real printed dose of selected tablet designs and their sustained drug release was established. The release profiles were analyzed using different mathematical model fits and compared in terms of mean dissolution times (MDT). Finally, in-vivo/in-vitro correlation (IVIVC) and physiologically based pharmacokinetic (PBPK) modeling showed that a paradigm patient group could be covered with the dosage forms produced., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microneedles (MN) have emerged as an innovative technology for drug delivery, offering a minimally invasive approach to administer therapeutic agents. Recent applications have included ocular drug delivery, requiring the manufacture of sub-millimeter needle arrays in a reproducible and reliable manner. The development of 3D printing technologies has facilitated the fabrication of MN via mold production, although there is a paucity of information available regarding how the printing parameters may influence crucial issues such as sharpness and penetration efficacy. In this study, we have developed and optimized a 3D-printed MN micro-mold using stereolithography (SLA) 3D printing to prepare a dissolving ocular MN patch. The effects of a range of parameters including aspect ratio, layer thickness, length, mold shape and printing orientation have been examined with regard to both architecture and printing accuracy of the MN micro-mold, while the effects of printing angle on needle fidelity was also examined for a range of basic shapes (conical, pyramidal and triangular pyramidal). Mechanical strength and in vitro penetration of the polymeric (PVP/PVA) MN patch produced from reverse molds fabricated using MN with a range of shapes and height, and aspect ratios were assessed, followed by ex vivo studies of penetration into excised scleral and corneal tissues. The optimization process identified the parameters required to produce MN with the sharpest tips and highest dimensional fidelity, while the ex vivo studies indicated that these optimized systems would penetrate the ocular tissue with minimal applied pressure, thereby allowing ease of patient self-administration., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Rawan Fitaihi reports financial support was provided by King Saud University College of Pharmacy. D Craig is on the editorial board of IJP If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Pulsatile drug delivery is hardly achieved by conventional gastro-retentive dosage forms. Artesunate as a typical anti-malaria medicine needs oral pulsatile release. Here, artesunate-loaded pulsatile-release multi-unit gastro-retentive tablets (APGTs) were prepared with a semi-solid extrusion three-dimensional (3D) printing method. An APGT was composed of three units: artesunate-loaded immediate and delayed release units and a block unit. The matrix of the immediate/delayed release units consisted of polyvinylpyrrolidone (PVP) K30 and croscarmellose sodium, which improved the rapid release of artesunate when contacting water. The block unit consisted of octadecanol, hydroxypropyl methyl cellulose K15M, PVP K30, and poloxamer F68. APGTs showed multi-phase release in simulated gastric liquids (SGLs). The first immediate release phase continued for 1 h followed by a long block phase for 7 h. The second rapid release phase was initiated when the eroded holes in the block unit extended to the inner delayed release unit, and this phase continued for about 14 h. Low-density APGTs could ensure their long-term floating in the stomach. Oral APGTs remained in the rabbit stomach for about 20 h. 3D printing provides a new strategy for the preparation of oral pulsatile-release tablets., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Production of amorphous solid dispersions (ASDs) is an effective strategy to promote the solubility and bioavailability of poorly water soluble medicinal substances. In general, ASD is manufactured using a variety of classic and modern techniques, most of which rely on either melting or solvent evaporation. This proof-of-concept study is the first ever to introduce electromagnetic drop-on-demand (DoD) technique as an alternative solvent evaporation-based method for producing ASDs. Herein 3D printing of ASDs for three drug-polymer combinations (efavirenz-Eudragit L100-55, lumefantrine-hydroxypropyl methylcellulose acetate succinate, and favipiravir-polyacrylic acid) was investigated to ascertain the reliability of this technique. Polarized light microscopy, differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and Fourier Transform  Infrared (FTIR) spectroscopy results supported the formation of ASDs for the three drugs by means of DoD 3D printing, which significantly increases the equilibrium solubility of efavirenz from 0.03 ± 0.04 µg/ml to 21.18 ± 4.20 µg/ml, and the equilibrium solubility of lumefantrine from 1.26 ± 1.60 µg/ml to 20.21 ± 6.91 µg/ml. Overall, the reported findings show how this new electromagnetic DoD technology can have a potential to become a cutting-edge 3D printing solvent-evaporation technique for on-demand and continuous manufacturing of ASDs for a variety of drugs., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The authors are co-inventors of related intellectual property (IP). Maniruzzaman. M., an author of this manuscript, holds stock in, serves on a scientific advisory board for, or is a consultant for CoM3D Ltd. (Surrey, UK), Septum Solutions LLC (Houston, TX, USA), and DosePlus Therapeutics Inc. (Princeton, NJ, USA). The terms of this arrangement have been reviewed and approved by The University of Texas at Austin and The University of Mississippi in accordance with its policies on objectivity in research., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: To study the feasibility of using poly methyl methacrylate (PMMA) filament and fused deposition modeling (FDM) to manufacture denture bases via the development of a study that considers both conventional and additive-based manufacturing techniques., Materials and Methods: Five sample groups were compared: heat and cold cured acrylic resins, CAD/CAM milled PMMA, 3D-printed PMMA (via FDM), and 3D-printed methacrylate resin (via stereolithography, SLA). All groups were subjected to mechanical testing (flexural strength, impact strength, and hardness), water sorption and solubility tests, a tooth bonding test, microbiological assessment, and accuracy of fit measurements. The performance of sample groups was referred to ISO 20795-1 and ISO/TS 19736. The data was analyzed using one-way ANOVA., Results: Samples manufactured using FDM performed within ISO specifications for mechanical testing, water sorption, and solubility tests. However, the FDM group failed to achieve the ISO requirements for the tooth bonding test. FDM samples presented a rough surface finish which could ultimately encourage an undesirable high level of microbial adhesion. For accuracy of fit, FDM samples showed a lower degree of accuracy than existing materials., Conclusions: Although FDM samples were a cost-effective option and were able to be quickly manufactured in a reproducible manner, the results demonstrated that current recommended testing regimes for conventionally manufactured denture-based polymers are not directly applicable to additive-manufactured denture base polymers. Therefore, new standards should be developed to ensure the correct implementation of additive manufacturing techniques within denture-based fabrication workflow., (© 2024 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)

Scleroderma is a chronic and progressive autoimmune disorder of connective tissues often causing lesions and deformities of the hands. Individuals affected by this condition experience daily life limitations and are typically unable to take part in sport activities that involve impacts on the hands. In this article we describe the design and manufacturing of custom-made hand orthoses to play sitting volleyball, for an elite paralympic athlete affected by scleroderma. The devices consist of a carbon fibre shell with an internal silicone padding and an external polymeric multilayer cover. The manufacturing of the orthoses involves digital modelling, 3D printing, composite lamination and an innovative method to create a strong and durable chemical bonding between silicone and carbon fibre. The internal silicone padding proved to be effective in hosting and protecting the hands, whereas the external shell with polymeric multilayer cover allowed to dampen the ball shocks while effectively hitting the ball. Indeed, these devices allowed the athlete to take part in the 2020 Tokyo Paralympic games and were used for two years without showing any damage., Competing Interests: Declaration of competing interest None declared., (Copyright © 2024. Published by Elsevier Ltd.)

Mass transport properties within three-dimensional (3D) scaffold are essential for tissue regeneration, such as various fluid environmental cues influence mesenchymal stem cells differentiation. Recently, 3D printing has been emerging as a new technology for scaffold fabrication by controlling the scaffold pore geometry to affect cell growth environment. In this study, the flow field within scaffolds in a perfusion system was investigated with uniform structures, single gradient structures and complex gradient structures using computational fluid dynamics (CFD) method. The CFD results from those uniform structures indicate the fluid velocity and fluid shear stress within the scaffold structure increased as the filament diameter increasing, pore width decreasing, pore shape decreased from 90° to 15°, and layer configuration changing from lattice to stagger structure. By assembling those uniform structure as single gradient structures, it is noted that the fluid dynamic characterisation within the scaffold remains the same as the corresponding uniform structures. A complex gradient structure was designed to mimic natural osteochondral tissue by assembly the uniform structures of filament diameter, pore width, pore shape and layer configuration. The results show that the fluid velocity and fluid shear stress within the complex gradient structure distribute gradually increasing and their maximum magnitude were from 1.15 to 3.20 mm/s, and from 12 to 39 mPa, respectively. CFD technique allows the prediction of velocity and fluid shear stress within the designed 3D gradient scaffolds, which would be beneficial for the tissue scaffold development for interfacial tissue engineering in the future., Competing Interests: Declaration of competing interest There are no competing interests to declare., (Crown Copyright © 2024. Published by Elsevier Ltd. All rights reserved.)

INTRODUCTION: The absence of a consistent downward G vector can make separation of gases from liquids challenging, such as in field medicine without stable upright equipment or during spaceflight. This limits the use of medical equipment and procedures like administration of intravenous (IV) fluids in microgravity and can make field medicine hazardous. Administering IV fluids and medications in microgravity requires a technique to separate air from the liquid phase. Current commercial filters for separation of gases are incompatible with high flow and blood. We present a novel filter designed to provide adequate air clearance without a consistent downward G vector. METHODS: Inline air-eliminating filters were designed for use with IV fluid tubing in microgravity using computer-aided design software and printed using nylon 12 on an EOS Selective Laser Sintering 3D printer. A 0.2-μm membrane filter was adhered around a central, hollow pillar with external spiral baffles allowing separation and venting of air from the fluid. Results were compared against commercially available inline air-eliminating filters. RESULTS: The 3D-printed filters outperformed the commercial filters in both percentage of air removed and flow rates. The centrifugal, baffled filter had flow rates that far exceeded the commercial filters during rapid transfusion. DISCUSSION: IV fluid administration is an often underappreciated and a necessary basic requirement for medical treatment. An air-eliminating filter compatible with blood and rapid transfusion was developed and validated with crystalloid solutions to allow the successful administration of IV fluid and medication without a consistent downward G vector. Formanek A, Townsend J, Ottensmeyer MP, Kamine TH. A novel 3D-printed gravity-independent air-eliminating filter for rapid intravenous infusions . Aerosp Med Hum Perform. 2024; 95(6):327-332.

The challenge of integrating hydroxyapatite nanoparticles (nHAp) with polymers is hindered by the conflict between the hydrophilic and hygroscopic properties of nHAp and the hydrophobic properties of polymers. This conflict particularly affects the materials when calcium phosphates, including nHAp, are used as a filler in composites in thermal processing applications such as 3D printing with fused filament fabrication (FFF). To overcome this, we propose a one-step surface modification of nHAp with calcium stearate monolayer. Moreover, to build the scaffold with suitable mechanical strength, we tested the addition of nHAp with diverse morphology-spherical, plate- and rod-like nanoparticles. Our analysis showed that the composite of polycaprolactone (PCL) reinforced with nHAp with rod and plate morphologies modified with calcium stearate monolayer exhibited a significant increase in compressive strength. However, composites with spherical nHAp added to PCL showed a significant reduction in compressive modulus and compressive strength, but both parameters were within the applicability range of hard tissue scaffolds. None of the tested composite scaffolds showed cytotoxicity in L929 murine fibroblasts or MG-63 human osteoblast-like cells, supporting the proliferation of the latter. Additionally, PCL/nHAp scaffolds reinforced with spherical nHAp caused osteoactivation of bone marrow human mesenchymal stem cells, as indicated by alkaline phosphatase activity and COL1, RUNX2, and BGLAP expression. These results suggest that the calcium stearate monolayer on the surface of the nHAp particles allows the production of polymer/nHAp composites suitable for hard tissue engineering and personalized implant production in 3D printing using the FFF technique., (© 2024 Wiley Periodicals LLC.)

Three-dimensional (3D) printing is one of the world's top novel technologies in the food industry due to the production of food in different conditions and places (restaurants, homes, catering, schools, for dysphagia patients, and astronauts' food) and the production of personalized food. Nowadays, 3D printers are used in the main food industries, including meat, dairy, cereals, fruits, and vegetables, and have been able to produce successfully on a small scale. However, due to the expansion of this technology, it has challenges such as high-scale production, selection of printable food, formulation optimization, and food production according to the consumer's opinion. Food additives (gums, enzymes, proteins, starches, polyphenols, spices, probiotics, algae, edible insects, oils, salts, vitamins, flavors, and by-products) are one of the main components of the formulation that can be effective in food production according to the consumer's attitude. Food additives can have the highest impact on textural and sensory characteristics, which can be effective in improving consumer attitudes and reducing food neophobia. Most of the 3D-printed food cannot be printed without the presence of hydrocolloids, because the proper flow of the selected formulation is one of the key factors in improving the quality of the printed product. Functional additives such as probiotics can be useful for specific purposes and functional food production. Food personalization for specific diseases with 3D printing technology requires a change in the formulation, which is closely related to the selection of correct food additives. For example, the production of 3D-printed plant-based steaks is not possible without the presence of additives, or the production of food for dysphagia patients is possible in many cases by adding hydrocolloids. In general, additives can improve the textural, rheological, nutritional, and sensory characteristics of 3D printed foods; so, investigating the mechanism of the additives on all the characteristics of the printed product can provide a wide perspective for industrial production and future studies., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Repairing and regenerating damaged tissues or organs, and restoring their functioning has been the ultimate aim of medical innovations. 'Reviving healthcare' blends tissue engineering with alternative techniques such as hydrogels, which have emerged as vital tools in modern medicine. Additive manufacturing (AM) is a practical manufacturing revolution that uses building strategies like molding as a viable solution for precise hydrogel manufacturing. Recent advances in this technology have led to the successful manufacturing of hydrogels with enhanced reproducibility, accuracy, precision, and ease of fabrication. Hydrogels continue to metamorphose as the vital compatible bio-ink matrix for AM. AM hydrogels have paved the way for complex 3D/4D hydrogels that can be loaded with drugs or cells. Bio-mimicking 3D cell cultures designed via hydrogel-based AM is a groundbreaking in-vivo assessment tool in biomedical trials. This brief review focuses on preparations and applications of additively manufactured hydrogels in the biomedical spectrum, such as targeted drug delivery, 3D-cell culture, numerous regenerative strategies, biosensing, bioprinting, and cancer therapies. Prevalent AM techniques like extrusion, inkjet, digital light processing, and stereo-lithography have been explored with their setup and methodology to yield functional hydrogels. The perspectives, limitations, and the possible prospects of AM hydrogels have been critically examined in this study., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Ankle arthritis is becoming more common and can be pain-ful and debilitating. As the disease progresses, degenera-tive cystic changes may be found in the distal fibula, distal tibia, and talus. After failure of non-operative modalities, arthrodesis is often considered the surgical intervention of choice, but this leaves the patient with reduced range of motion, altered gait, and can negatively impact adjacent joints of the foot. Total ankle arthroplasty has been found to be an effective surgical option for ankle arthritis but is contraindicated in patients with talar collapse. When this is the case, a more personalized approach for preserving ankle motion is necessary. We present the case of a 65-year-old male with severe right ankle arthritis and talar collapse treated with a custom three-dimensionally printed talus and concurrent total ankle replacement with 2-year follow-up.

Decellularized extracellular matrix (dECM) is an excellent natural source for 3D bioprinting materials due to its inherent cell compatibility. In vat photopolymerization, the use of dECM-based bioresins is just emerging, and extensive research is needed to fully exploit their potential. In this study, two distinct methacryloyl-functionalized, photocrosslinkable dECM-based bioresins were prepared from digested porcine liver dECM through functionalization with glycidyl methacrylate (GMA) or conventional methacrylic anhydride (MA) under mild conditions for systematic comparison. Although the chemical modifications did not significantly affect the structural integrity of the dECM proteins, mammalian cells encapsulated in the respective hydrogels performed differently in long-term culture. In either case, photocrosslinking during 3D (bio)printing resulted in transparent, highly swollen, and soft hydrogels with good shape fidelity, excellent biomimetic properties and tunable mechanical properties (~ 0.2-2.5 kPa). Interestingly, at a similar degree of functionalization (DOF ~ 81.5-83.5 %), the dECM-GMA resin showed faster photocrosslinking kinetics in photorheology resulting in lower final stiffness and faster enzymatic biodegradation compared to the dECM-MA gels, yet comparable network homogeneity as assessed via Brillouin imaging. While human hepatic HepaRG cells exhibited comparable cell viability directly after 3D bioprinting within both materials, cell proliferation and spreading were clearly enhanced in the softer dECM-GMA hydrogels at a comparable degree of crosslinking. These differences were attributed to the additional hydrophilicity introduced to dECM via methacryloylation through GMA compared to MA. Due to its excellent printability and cytocompatibility, the functional porcine liver dECM-GMA biomaterial enables the advanced biofabrication of soft 3D tissue analogs using vat photopolymerization-based bioprinting., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Marie Weinhart reports financial support was provided by German Research Foundation. Sebastian Seiffert reports financial support was provided by German Research Foundation. Beate Koksch reports financial support was provided by German Research Foundation. Igor Maximilian Sauer reports financial support was provided by German Research Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Surgical procedures to correct hip dysplasia associated with subluxation or dislocation of the femoral head are complex. The 3D geometric abnormalities of the acetabulum and proximal femur vary across patients. We, therefore, suggest a patient-specific surgical treatment involving computer-assisted 3D planning of the peri-acetabular osteotomies, taking into account the femoral head position; 3D printing of patient-specific guides for the cuts, repositioning, and fixation; and intra-operative application of the simulated displacements with their fixation. LEVEL OF EVIDENCE: IV., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

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.

The primary goal of bone tissue engineering is to restore and rejuvenate bone defects by using a suitable three-dimensional scaffold, appropriate cells, and growth hormones. Various scaffolding methods are used to fabricate three-dimensional scaffolds, which provide the necessary environment for cell activity and bone formation. Multiple materials may be used to create scaffolds with hierarchical structures that are optimal for cell growth and specialization. This study examines a notion for creating an optimal framework for bone regeneration using a combination of the robocasting method and the electrospinning approach. Research indicates that the integration of these two procedures enhances the benefits of each method and provides a rationale for addressing their shortcomings via this combination. The hybrid approach is anticipated to provide a manufactured scaffold that can effectively replace bone defects while possessing the necessary qualities for bone regeneration., (© 2024. The Author(s) under exclusive licence to Biomedical Engineering Society.)

Objectives: To incorporate the nanostructured silver vanadate decorated with silver nanoparticles (AgVO 3 ) into denture base materials: heat-cured (HC) and 3D printed (3DP) resins, at concentrations of 2.5 %, 5 %, and 10 %; and to evaluate the antimicrobial activity in two multi-species biofilm: (1) Candida albicans, Candida glabrata, and Streptococcus mutans, (2) Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus, and the wettability., Methods: The AgVO 3 was added to the HC powder, and printed samples were coated with 3DP with AgVO 3 incorporated. After biofilm formation, the antimicrobial activity was evaluated by colony forming units per milliliter (CFU/mL), metabolic activity, and epifluorescence microscopy. Wettability was assessed by the contact angles with water and artificial saliva., Results: In biofilm (1), HC-5 % and HC-10 % showed activity against S. mutans, HC-10 % against C. glabrata, and HC-10 % and 3DP-10 % had higher CFU/mL of C. albicans. 3DP-5 % had lower metabolic activity than the 3DP control. In biofilm (2), HC-10 % reduced S. aureus and P. aeruginosa, and HC-5 %, 3DP-2.5 %, and 3DP-5 % reduced S. aureus. 3DP incorporated with AgVO 3 , HC-5 %, and HC-10 % reduced biofilm (2) metabolic activity. 3DP-5 % and 3DP-10 % increased wettability with water and saliva., Conclusion: HC-10 % was effective against C. glabrata, S. mutans, P. aeruginosa, and S. aureus, and HC-5 % reduced S. mutans and S. aureus. For 3DP, 2.5 % and 5 % reduced S. aureus. The incorporation of AgVO 3 into both resins reduced the metabolic activity of biofilms but had no effect on C. albicans. The wettability of the 3DP with water and saliva increased with the addition of AgVO 3 ., Clinical Significance: The incorporation of silver vanadate into the denture base materials provides antimicrobial efficacy and can prevent the aggravation of oral and systemic diseases. The incorporation of nanomaterials into printed resins is challenging and the coating is an alternative to obtain the inner denture base with antimicrobial effect., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Purpose: 3D printing technologies have become an integral part of modern life, and the most routinely used materials in reconstructive surgery in children are biodegradable materials. The combination of these two technologies opens up new possibilities for the application of innovative methods in neurosurgery and a patient-centered approach in medical care. The aim of the study was to determine whether a physician without specialized programming and printing skills could independently create materials in a clinical setting for the treatment of patients., Methods: We conducted a preclinical study on 15 male Balb-C mice. Cylindrical materials made of polylactic acid (PLA) plastic were 3D printed. Sterilization of the obtained material was performed using a cold plasma sterilizer with hydrogen peroxide vapor and its plasma. The sterile material was implanted subcutaneously into the mice for 30 days, followed by histological examination. Using open-source software for modeling and printing, plates and screws made of PLA plastic were manufactured. The produced components were tested in the biomedical laboratory of the institute., Results: The histological material showed that no inflammatory changes were observed at the implantation site during the entire observation period. The cellular composition is mainly represented by macrophages and fibroblasts. There was a gradual resolution of the material and its replacement by native tissues. Research conducted to assess the effectiveness of material sterilization in a cold plasma sterilizer demonstrated its high bactericidal efficiency., Conclusion: The method we developed for obtaining biodegradable plates and fixation elements on a 3D printer is easy to use and has demonstrated safety in a preclinical study on an animal model., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Several reviews and meta-analyses about the value of three-dimensional (3D) printing in anatomy education have been published in the last years, with variable-and sometimes confusing- outcomes. We performed a review of those reviews, in order to shed light on the results concerning the effectiveness of 3D printing in anatomy education, compared to specific traditional methods and other technologies., Methods: The electronic databases PubMed, ERIC and Cochrane library were searched for reviews or meta-analyses with purpose to investigate the effectiveness of 3D printing in undergraduate and postgraduate anatomy education., Results: Seven papers were included: four systematic reviews with meta-analysis, one narrative, one scoping and one systematic review. Overall, it has been shown that 3D printing is more effective than two-dimensional (2D) images for undergraduate health science students, but not for medical residents. Also, it seems to be more effective than 2D methods for teaching anatomy of some relatively complex structures, such as the nervous system. However, there is generally lack of evidence about the effectiveness of 3D printing in comparison with other 3D visualization methods., Conclusions: For students, the effectiveness of 3D printing in anatomy education is higher than 2D methods. There is need for studies to investigate the effectiveness of 3D printing in comparison with other 3D visualization methods, such as cadaveric dissection, prosection and virtual reality. There is also need for research to explore if 3D printing is effective as a supplementary tool in a blended anatomy learning approach., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

Background: Reconstructing bone defects in the upper extremities and restoring their functions poses a significant challenge. In this study, we describe a novel workflow for designing and manufacturing customized bone cement molds using 3D printing technology to reconstruct upper extremity defects after bone tumor resection., Methods: Computer tomography data was acquired from the unaffected upper extremities to create a detachable mold, which can be customized to fit the joint precisely by shaping the bone cement accordingly. Fourteen patients who underwent reconstructive surgery following bone tumor resection in the proximal humerus (13 cases) or distal radius (1 case) between January 2014 and December 2022 were retrospectively evaluated. The medical records of this case series were reviewed for the demographic, radiological, and operative data. Metastasis, local recurrence, and complication were also reviewed. Additionally, Musculoskeletal Tumor Society Score (MSTS) and Visual Analogue Scale (VAS) were used to assess clinical outcomes., Results: The mean follow-up period was 49.36 ± 15.18 months (range, 27-82 months). At the end of follow-up, there were no cases of metastasis or recurrence, and patients did not experience complications such as infection, dislocation, or implant loosening. Two cases complicated with subluxation (14.3%), and 1 case underwent revision surgery for prosthetic fracture (7.1%). The average MSTS score was 23.2 ± 1.76 (77.4%, range, 66.7%-86.7%), and the postoperative VAS score was 1.86 ± 1.03 (range, 1-4), which was significantly lower than that before surgery (average preoperative VAS score was 5.21 ± 2.00 (range, 2-8)) ( P < .001)., Conclusion: Customized 3D molds can be utilized to shape bone cement prostheses, which may serve as a potential alternative for reconstructing the proximal humerus and distal radius following en bloc resection of bone tumors. This reconstruction strategy offers apparent advantages, including precise matching of articular surfaces and comparatively reduced costs., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Resin-based three-dimensional (3D) printing finds extensive application in the field of dentistry. Although studies of cytotoxicity, mechanical and physical properties have been conducted for newly released 3D printing resins such as Crowntec (Saremco), Temporary Crown Resin (Formlabs) and Crown & Bridge (Nextdent), the resistance of these materials to esterases in saliva has not been demonstrated at the molecular level. Therefore, in this study, the binding affinities and stability of these new 3D printing resins to the catalytic sites of esterases were investigated using molecular docking and molecular mechanics with Poisson-Bolzmann and surface area solvation (MM/PBSA) methods after active pocket screening. Toxicity predictions of the materials were also performed using ProTox-II and Toxtree servers. The materials were analyzed for mutagenicity, cytotoxicity, and carcinogenicity, and LD 50 values were predicted from their molecular structures. The results indicated that out of the three novel 3D printing materials, Nexdent exhibited reduced binding affinity to esterases, indicating enhanced resistance to enzymatic degradation and possessing a superior toxicity profile., (© 2024 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

Introduction: The use of 3-dimensional (3D) printing techniques in fabricating crowns has increased the demand for bracket bonding onto these surfaces. The objective was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded onto 3D-printed crowns using primer-incorporated orthodontic adhesives and 3D printing materials as orthodontic adhesives., Methods: A total of 160 crowns were printed with two 3D printing materials, DentaTOOTH (Asiga, Sydney, Australia) (group A) and NextDent C&B Micro Filled Hybrid (3D Systems, Soesterberg, Netherlands) (group N). Each group was randomly divided into 4 adhesive subgroups (n = 20): Transbond XT (for groups A [ATX] and N [NTX]; 3M Unitek, Monrovia, Calif), Ortho Connect (for groups A [AOC] and N [NOC]; GC Corporation., Tokyo, Japan), Orthomite LC (for groups A [AOM] and N [NOM]; Sun Medical, Co Ltd, Moriyama, Shiga, Japan), and unpolymerized liquid state of 3D printing resin (for groups A [AA] and N [NN]). SBS was measured with a universal testing machine at a crosshead speed of 0.5 mm/min. The adhesive remnant index and the mode of failure were analyzed under the microscope. Statistical analysis was performed at a significance level of α = 0.05., Results: When used as adhesives (AA and NN), 3D printing materials showed no statistically significant difference in SBS compared with Transbond XT (ATX and NTX, respectively). In group N, NN showed a significantly higher SBS than primer-incorporated orthodontic adhesives (NOC and NOM; P <0.001). Adhesive failures were only observed in primer-incorporated orthodontic adhesives (AOC, NOC, AOM, and NOM)., Conclusions: Primer-incorporated orthodontic adhesives, as well as unpolymerized 3D printing materials employed as orthodontic adhesives on 3D-printed crowns, exhibited comparable bonding strength to Transbond XT without surface modification. Despite variations in adhesive-related factors, all measurements stayed within clinically acceptable ranges, highlighting the potential of these materials for orthodontic bonding on 3D-printed crowns, simplifying clinical procedures without compromising bond strength., (Copyright © 2024. Published by Elsevier Inc.)

The three-dimensional-printed Ti6Al4V implant (3DTi) has been widely accepted for the reconstruction of massive bone defects in orthopedics owing to several advantages, such as its tailored shape design, avoiding bone graft and superior bone-implant interlock. However, the osteoinduction activity of 3DTi is inadequate when applied clinically even though it exhibits osteoconduction. This study developes a comprehensive coatless strategy for the surface improvement of 3DTi through copper (Cu) ion implantation and ultraviolet (UV) photofunctionalization to enhance osteoinductivity. The newly constructed functional 3DTi (UV/Ti-Cu) achieved stable and controllable Cu doping, sustained Cu 2+ releasing, and increased surface hydrophilicity. By performing cellular experiments, we determined that the safe dose range of Cu ion implantation was less than 5×10 16 ions/cm 2 . The implanted Cu 2+ enhanced the ALP activity and the apatite formation ability of bone marrow stromal cells (BMSCs) while slightly decreasing proliferation ability. When combined with UV photofunctionalization, cell adhesion and proliferation were significantly promoted and bone mineralization was further increased. Meanwhile, UV/Ti-Cu was conducive to the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro, theoretically facilitating vascular coupling osteogenesis. In conclusion, UV/Ti-Cu is a novel attempt to apply two coatless techniques for the surface modification of 3DTi. In addition, it is considered a potential bone substrate for repairing bone defects., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The production of sustainable materials with properties aimed at the additive manufacturing of electrochemical sensors has gained prestige in the scientific scenario. Here, a novel lab-made composite material using graphite (G) and carbon nitride (C 3 N 4 ) embedded into polylactic acid (PLA) biopolymer is proposed to produce 3D-printed electrodes. PLA offers printability and mechanical stability in this composition, while G and C 3 N 4 provide electrical properties and electrocatalytic sites, respectively. Characterizations by Raman and infrared spectroscopies and Energy Dispersive X-rays indicated that the G/C 3 N 4 /PLA composite was successfully obtained, while electron microscopy images revealed non-homogeneous rough surfaces. Better electrochemical properties were achieved when the G/C 3 N 4 /PLA proportion (35:5:60) was used. As a proof of concept, amaranth (AMR), a synthetic dye, was selected as an analyte, and a fast method using square wave voltammetry was developed. Utilizing the 3D-printed G/C 3 N 4 /PLA electrode, a more comprehensive linear range (0.2 to 4.2 μmol/L), a 5-fold increase in sensitivity (9.83 μmol -1 L μA), and better limits of detection (LOD = 0.06 μmol/L) and quantification (LOQ = 0.18 μmol/L) were achieved compared to the G/PLA electrode. Samples of jelly, popsicles, isotonic drinks, and food flavoring samples were analyzed, and similar results to those obtained by UV-vis spectrometry confirmed the method's reliability. Therefore, the described sensor is a simple, cost-effective alternative for assessing AMR in routine food analysis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The human nervous system is an incredibly intricate physiological network, and neural cells lack the ability to repair and regenerate after a brain injury. 3-dimensional (3D) bioprinting technology offers a promising strategy for constructing biomimetic organ constructs and in vitro brain/disease models. The bioink serves as a pivotal component that emulates the microenvironment of biomimetic construct and exerts a profound influence on cellular behaviors. In this study, a series of mechanically adjustable and dual crosslinking bioinks were developed using photocrosslinkable methacrylated silk fibroin (SilMA) in combination with the ionic crosslinking material, pectin, or pectin methacryloyl (PecMA) with silk fibroin (SF) supplementation. SilMA/pectin exhibited superior properties, with SilMA providing biocompatibility and adjustable mechanical properties, while the addition of pectin enhanced printability. The porous structure supported neural cell growth, and 15 % SilMA/0.5 % pectin bioinks displayed excellent printability and shape fidelity. Neural stem/progenitor cells (NSPCs)-loaded bioinks were used to construct a 3D brain model, demonstrating sustained vitality and high neuronal differentiation without the need for growth factors. The SilMA/pectin bioinks demonstrated adjustable mechanical properties, favorable biocompatibility, and an environment highly conducive to neural induction, offering an alternative approach for neural tissue engineering applications or in vitro brain models., Competing Interests: Declaration of competing interest The authors declare no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)