Clinical effect of digitalized designed and 3D-printed repositioning splints in the treatment of anterior displacement of temporomandibular joint disc

OBJECTIVE

To compare the treatment effectiveness of digitized and 3D-printed repositioning splints with that of conventional repositioning splints in the treatment of anterior displacement of the temporomandibular joint disc.

METHODS

This retrospective study included 96 patients with disc displacement of the anterior temporomandibular joint. They were treated with either digitally designed and 3D-printed repositioning splints or traditional splints and followed up for at least six months. Changes in signs and symptoms such as pain and mouth opening before and after treatment were recorded to evaluate treatment outcomes.

RESULTS

During the first month of treatment, both the digitally designed and 3D-printed repositioning splint groups (Group B) and the traditional repositioning splint group (Group A) showed significant increases in mouth opening, with increases of 4.93 ± 3.06 mm and 4.07 ± 4.69 mm, respectively, and there was no significant difference between the two groups. Both groups had a significant reduction in visual analog scale (VAS) pain scores, with Group B showing a greater reduction of 1.946 ± 1.113 compared to 1.488 ± 0.978 in Group A (P < 0.05). By the sixth month, Group B's mouth opening further improved to 38.65 ± 3.22 mm (P < 0.05), while Group A's mouth opening did not significantly improve. Regarding pain, Group A's VAS score decreased by 0.463 ± 0.778 after one month, and Group B's score decreased by 0.455 ± 0.715; both groups showed significant reductions, but there was no significant difference between the two groups.

CONCLUSION

Compared with traditional repositioning splints, digitally designed and 3D-printed repositioning splints are more effective at reducing patient pain and improving mouth opening. 3D-printed repositioning splints are an effective treatment method for temporomandibular joint disc displacement and have significant potential for widespread clinical application.

Mandibular Fixed Prosthesis With A 3d-Printed Subperiosteal Implant: A Case Report

BACKGROUND

This case report aims to present the successful restoration of the atrophic partially edentulous posterior mandible using custom-made subperiosteal implants.

CASE DESCRIPTION

The fixed prosthesis restoration was achieved using CAD-CAM technologies and 3D metal printing methods. The partially edentulous 58-year-old patient expressed a preference not to undergo bone augmentation procedures. The patient with teeth in the anterior mandible was treated with two separate custom-made subperiosteal implants. A custom-made prosthesis was fabricated from sintered titanium using machined subperiosteal implants with a universal external connection.

PRACTICAL IMPLICATIONS

Subperiosteal implants offer several advantages over conventional bone grafting plus intraosseous implant placement techniques, such as the simple, one-step procedure for atrophic jaws, streamlining the treatment process and reducing the overall time involved. Treatments using subperiosteal implants can be an alternative solution for individuals with severely atrophic jaws. Longer-term studies in a larger sample are warranted to corroborate previous reports.

An evaluation of the usability and durability of 3D printed versus standard suture materials

The capability to produce suture material using three-dimensional (3D) printing technology may have applications in remote health facilities where rapid restocking of supplies is not an option. This is a feasibility study evaluating the usability of 3D-printed sutures in the repair of a laceration wound when compared with standard suture material. The 3D-printed suture material was manufactured using a fused deposition modelling 3D printer and nylon 3D printing filament. Study participants were tasked with performing laceration repairs on the pigs' feet, first with 3-0 WeGo nylon suture material, followed by the 3D-printed nylon suture material. Twenty-six participants were enrolled in the study. Survey data demonstrated statistical significance with how well the 3D suture material performed with knot tying, 8.9 versus 7.5 (p = 0.0018). Statistical significance was observed in the 3D-printed suture's ultimate tensile strength when compared to the 3-0 Novafil suture (274.8 vs. 199.8 MPa, p = 0.0096). The 3D-printed suture also demonstrated statistical significance in ultimate extension when compared to commercial 3-0 WeGo nylon suture (49% vs. 37%, p = 0.0215). This study was successful in using 3D printing technology to manufacture suture material and provided insight into its usability when compared to standard suture material.

Multilevel Heterogeneous Interfaces Enhanced Polarization Loss of 3D-Printed Graphene/NiCoO2/Selenides Aerogels for Boosting Electromagnetic Energy Dissipation

Heterointerface engineering is an attractive approach to modulating electromagnetic (EM) parameters and EM wave absorption performance. However, the weak interfacial interactions and poor impedance matching would lead to unsatisfactory EM absorption performance due to the limitation of the construction materials and design strategies. Herein, multilevel heterointerface engineering is proposed by in situ growing nanosheet-like NiCoO2 and selenides with abundant interface structures on 3D-printed graphene aerogel (GA) skeletons, which strengthens the interfacial effect and improves the dielectric polarization loss. Benefiting from the features of substantially enhanced polarization loss and optimized impedance matching, the graphene/S-NiCoO2/selenides (G/S-NCO/Se) have achieved brilliant EM wave absorption performance with a strong reflection loss (RL) value of -60.7 dB and a broad effective absorption bandwidth (EAB) of 8 GHz, which is about six times greater than that of the graphene aerogel (-9.8 dB). Moreover, it is further confirmed by charge density differences and off-axis electron holography that a large amount of polarized charge accumulates at the interface, leading to significant polarization relaxation behaviors. This work provides a deep understanding of the effect of a multilevel heterogeneous interface on dielectric polarization loss, which injects a fresh and infinite vitality for designing high-efficiency EM wave absorbers.

Evaluation of the clinical application of personalized 3D printing and CAD/CAM resin crowns to replace stainless steel crowns in paediatric dentistry

BACKGROUND

Children with dental caries are treated with stainless steel metal crowns (SSC), but the aesthetics and precision still need to be improved. Currently, both 3D-printed resin crowns (PRC) and computer-aided design/computer-aided manufacture (CAD/CAM) resin crowns (CRC) meet the clinical requirements for crown applications in terms of strength, production time, cost, and aesthetics.

AIM

This study replaced SSC with customized resin crowns by 3D printing and CAD/CAM.

DESIGN

In this study, PRC, CRC, and SSC were used for incisor and molar restorations, and 60 crowns were made with 10 for each group. The fabrication efficiency, surface characteristics, marginal fit, and stability of the two different crowns were evaluated.

RESULTS

PRC and CRC show superior color and surface characteristics, though production times are longer (5.3-12.4 times and 3.3-9.1 times, respectively) than for SSC (p < .05). They, however, can be completed within 80 min. Edge gaps for PRC and CRC are significantly lower (13.0-19.2 times and 13.0-13.7 times) than for SSC (p < .05). All materials exhibit good stability.

CONCLUSION

The 3D-PRCs and CAD/CAM resin crowns may replace SSCs as a potential choice for clinical child caries.

Effect of thermal cycling on the flexural strength of 3-D printed, CAD/CAM milled and heat-polymerized denture base materials

BACKGROUND

This study compared the impact of thermal cycling on the flexural strength of denture-base materials produced through conventional and digital methods, using both subtractive and additive approaches.

METHODS

In total, 60 rectangular specimens were fabricated with specific dimensions for flexural strength tests. The dimensions were set according to the International Organization for Standardization (ISO) guideline 20795-1:2013 as 64 × 10 × 3.3 ± 0.2 mm. Specimens from each material group were divided into two subgroups (thermal cycled or nonthermal cycled, n = 10/group). We used distinct methods to produce three different denture-base materials: Ivobase (IB), which is a computer-aided-design/computer-aided-manufacturing-type milled pre-polymerized polymethyl methacrylate resin disc; Formlabs (FL), a 3D-printed denture-base resin; and Meliodent (MD), a conventional heat-polymerized acrylic. Flexural strength tests were performed on half of the samples without a thermal-cycle procedure, and the other half were tested after a thermal cycle. The data were analyzed using a two-way analysis of variance and a post hoc Tukey test (α = 0.05).

RESULTS

Based on the results of flexural-strength testing, the ranking was as follows: FL > IB > MD. The effect of thermal aging was statistically significant for the FL and IB bases, but not for the MD base.

CONCLUSIONS

Digitally produced denture bases exhibited superior flexural strength compared with conventionally manufactured bases. Although thermal cycling reduced flexural strength in all groups, the decrease was not statistically significant in the heat-polymerized acrylic group.

Engineered 3D ex vivo models to recapitulate the complex stromal and immune interactions within the tumor microenvironment

Cancer thrives in a complex environment where interactions between cellular and acellular components, surrounding the tumor, play a crucial role in disease development and progression. Despite significant progress in cancer research, the mechanism driving tumor growth and therapeutic outcomes remains elusive. Two-dimensional (2D) cell culture assays and in vivo animal models are commonly used in cancer research and therapeutic testing. However, these models suffer from numerous shortcomings including lack of key features of the tumor microenvironment (TME) & cellular composition, cost, and ethical clearance. To that end, there is an increased interest in incorporating and elucidating the influence of TME on cancer progression. Advancements in 3D-engineered ex vivo models, leveraging biomaterials and microengineering technologies, have provided an unprecedented ability to reconstruct native-like bioengineered cancer models to study the heterotypic interactions of TME with a spatiotemporal organization. These bioengineered cancer models have shown excellent capabilities to bridge the gap between oversimplified 2D systems and animal models. In this review article, we primarily provide an overview of the immune and stromal cellular components of the TME and then discuss the latest state-of-the-art 3D-engineered ex vivo platforms aiming to recapitulate the complex TME features. The engineered TME model, discussed herein, are categorized into three main sections according to the cellular interactions within TME: (i) Tumor-Stromal interactions, (ii) Tumor-Immune interactions, and (iii) Complex TME interactions. Finally, we will conclude the article with a perspective on how these models can be instrumental for cancer translational studies and therapeutic testing.

A xonotlite nanofiber bioactive 3D-printed hydrogel scaffold based on osteo-/angiogenesis and osteoimmune microenvironment remodeling accelerates vascularized bone regeneration

BACKGROUND

Coordination between osteo-/angiogenesis and the osteoimmune microenvironment is essential for effective bone repair with biomaterials. As a highly personalized and precise biomaterial suitable for repairing complex bone defects in clinical practice, it is essential to endow 3D-printed scaffold the above key capabilities.

RESULTS

Herein, by introducing xonotlite nanofiber (Ca6(Si6O17) (OH)2, CS) into the 3D-printed silk fibroin/gelatin basal scaffold, a novel bone repair system named SGC was fabricated. It was noted that the incorporation of CS could greatly enhance the chemical and mechanical properties of the scaffold to match the needs of bone regeneration. Besides, benefiting from the addition of CS, SGC scaffolds could accelerate osteo-/angiogenic differentiation of bone mesenchymal stem cells (BMSCs) and meanwhile reprogram macrophages to establish a favorable osteoimmune microenvironment. In vivo experiments further demonstrated that SGC scaffolds could efficiently stimulate bone repair and create a regeneration-friendly osteoimmune microenvironment. Mechanistically, we discovered that SGC scaffolds may achieve immune reprogramming in macrophages through a decrease in the expression of Smad6 and Smad7, both of which participate in the transforming growth factor-β (TGF-β) signaling pathway.

CONCLUSION

Overall, this study demonstrated the clinical potential of the SGC scaffold due to its favorable pro-osteo-/angiogenic and osteoimmunomodulatory properties. In addition, it is a promising strategy to develop novel bone repair biomaterials by taking osteoinduction and osteoimmune microenvironment remodeling functions into account.

3D printed guide-assisted percutaneous screw fixation for minimally displaced scaphoid waist fractures with delayed diagnosis or presentation

OBJECTIVES

To Investigate the value of 3D printed guide-assisted percutaneous management of minimally displaced scaphoid waist fractures(Herbert's B2) with delayed diagnosis or presentation.

METHODS

From October 2018 to February 2022, 10 patients with established delayed diagnoses and presentation of minimally displaced scaphoid waist fractures were treated with 3D printed guides assisted with percutaneous internal fixation without bone grafting. This technique was based on the patient's preoperative CT and imported into the software. Based on Boolean subtraction, the most centralized screw placement position was identified and a customized guide was produced. Intraoperative percutaneous insertion of the guide wire was assisted by the custom guide.

RESULTS

All 10 patients were successful in one attempt. The fractures healed at a mean of 7.7 weeks postoperatively (range 6-10 weeks). At a mean follow-up of 7.7 months (6-13 months), patients had excellent recovery of wrist function with minimal pain reduction. There were no major postoperative complications and the patients all returned to their previous activities before the injury.

CONCLUSIONS

Percutaneous internal fixation based on 3D printed guides is a safe and effective technique for delayed diagnosis or presentation of patients with minimally displaced fractures of the scaphoid waist. This method allows for easy insertion of screws and avoids multiple attempts.

Effect of Duplication Techniques on the Fitting Accuracy of CAD-CAM Milled, 3D-Printed, and Injection-Molded Mandibular Complete Denture Bases

BACKGROUND

Digital technology has been introduced in prosthodontics, and it has been widely used in denture duplication instead of a conventional denture duplication technique. However, research comparing different denture duplication techniques and how they affect the fitting accuracy of the denture base is scarce.

OBJECTIVES

The aim was to assess the impact of duplication techniques on the accuracy of the fitting surface of computer-aided design and manufacturing (CAD-CAM) milled, 3D-printed, and injection-molded complete denture bases (CDBs).

METHODOLOGY

This study involved fabricating a mandibular complete denture base with three marked dimples as reference marks (A, B, and C at the incisive papilla, right molar, and left molar areas) using a conventional compression molded technique. This denture was then scanned to generate a standard tessellation language (STL) file; after that, it was duplicated using three different techniques (milling, 3D printing, and injection molding) and five denture base resin materials-two milled CAD-CAM materials (AvaDent and IvoBase), two 3D-printed materials (NextDent and HARZ Labs), and one injection-molded material (iFlextm). Based on the denture base type, the study divided them into five groups (each with n = 10). An evaluation of duplication accuracy was conducted on the fitting surface of each complete denture base (CDB) using two assessment methods. The first method was a two-dimensional evaluation, which entailed linear measurements of the distances (A-B, A-C, and B-C) between reference points on both the scanned reference mandibular denture and the duplicated dentures. Additionally, a three-dimensional superimposition technique was employed, involving the overlay of the STL files of the dentures onto the reference denture's STL file. The collected data underwent statistical analysis using a one-way analysis of variance and Tukey's pairwise post hoc tests.

RESULTS

Both evaluation techniques showed significant differences in fitting surface accuracy between the tested CDBs (p ˂ 0.001), as indicated by one-way ANOVA. In addition, the milled CDBs (AvaDent and IvoBase) had significantly higher fitting surface accuracy than the other groups (p ˂ 0.001) and were followed by 3D-printed CDBs (NextDent and HARZ Labs), while the injection-molded (iFlextm) CDBs had the lowest accuracy (p ˂ 0.001).

CONCLUSIONS

The duplication technique of complete dentures using a CAD-CAM milling system produced superior fitting surface accuracy compared to the 3D-printing and injection-molded techniques.

3D Printing to Enable Self-Breathing Fuel Cells

Fuel cells rely on an effective distribution of the reactant gases and removal of the byproduct, that is, water. In this context, bipolar plates are the critical component for the effective management of these fluids, as these dictate to some extent the overall performance of polymer electrolyte membrane fuel cells (PEMFCs). Better bipolar plates can lead to a significant reduction in size, cost, and weight of fuel cells. Herein, we report on the use of photoresin 3D printing to fabricate alternative bipolar plates for operating self-breathing fuel cell stacks. The resulting stack made of 12 self-breathing PEMFCs achieved a power density of 0.3 W/cm2 under ambient conditions (25°C and 20% relative humidity), which is superior to the performance of previously reported self-breathing cells. The problems associated with hydrogen leaks and water flooding could be resolved by taking advantage of 3D printing to precisely fabricate monoblock shapes. The approach of 3D printing reported in this study demonstrates a new path in fuel cell manufacturing for small and portable applications where an important reduction in size and cost is important.

Comparison and Evaluation of Fracture Toughness of Milled, 3D-Printed, and Conventional Polymethyl Methacrylate: An In Vitro Study

Introduction

Dentures aim to replicate natural dentition's esthetics and functions as much as possible. With computer-aided design/computer-aided manufacturing (CAD/CAM) technology, dentistry had a new renaissance with workflow and materials.

Aim

The aim is to compare the fracture toughness of the milled, 3D-printed, and conventional polymethyl methacrylate (PMMA) to those processed conventionally.

Materials and Methods

10 CAD MILLED PMMA BLOCKS, 10 3D PRINTED PMMA BLOCKS, and 10 CONVENTIONAL (HEAT CURE) PMMA BLOCKS.

Results

A significant difference was seen in the mean flexural module when compared among three study groups as P < 0.05. It was found to be maximum in CAD/CAM PMMA, followed by conventional heat cure and 3D-printed PMMA.

Conclusion

Formlabs and Dentca (3D-printed) were significantly weaker in fracture toughness compared to Leucitone 199 (conventional) (P < 0.05). Leucitone 199 (conventional) was significantly weaker in fracture toughness compared to Avadent (CAD CAM) (P < 0.05).

Biomechanical comparison of titanium alloy additively manufactured and conventionally manufactured plate-screw constructs

AIM

To biomechanically compare the bending stiffness, strength, and cyclic fatigue of titanium additively manufactured (AM) and conventionally manufactured (CM) limited contact plates (LCP) of equivalent dimensions using plate-screw constructs.

METHODS

Twenty-four 1.5/2.0-mm plate constructs (CM: n = 12; AM: n = 12) were placed under 4-point bending conditions. Data were collected during quasi-static single cycle to failure and cyclic fatigue testing until implants plastically deformed or failed. Bending stiffness, bending structural stiffness, and bending strength were determined from load-displacement curves. Fatigue life was determined as number of cycles to failure. Median test variables for each method were compared using the Wilcoxon rank sum test within each group. Fatigue data was also analysed by the Kaplan-Meier estimator of survival function.

RESULTS

There was no evidence for a difference in bending stiffness and bending structural stiffness between AM and CM constructs. However, AM constructs exhibited greater bending strength (median 3.07 (min 3.0, max 3.4) Nm) under quasi-static 4-point bending than the CM constructs (median 2.57 (min 2.5, max 2.6) Nm, p = 0.006). Number of cycles to failure under dynamic 4-point bending was higher for the CM constructs (median 164,272 (min 73,557, max 250,000) cycles) than the AM constructs (median 18,704 (min 14,427, max 33,228) cycles; p = 0.02). Survival analysis showed that 50% of AM plates failed by 18,842 cycles, while 50% CM plates failed by 78,543 cycles.

CONCLUSION AND CLINICAL RELEVANCE

Additively manufactured titanium implants, printed to replicate a conventional titanium orthopaedic plate, were more prone to failure in a shorter fatigue period despite being stronger in single cycle to failure. Patient-specific implants made using this process may be brittle and therefore not comparable to CM orthopaedic implants. Careful selection of their use on a case/patient-specific basis is recommended.

The Influence of Dental Virtualization, Restoration Types, and Placement Angles on the Trueness and Contact Space in 3D-Printed Crowns: A Comprehensive Exploration

The current digital dentistry workflow has streamlined dental restoration production, but the effectiveness of digital virtual design and 3D printing for restorations still needs evaluation. This study explores the impact of model-free digital design and 3D-printing placement angles on restorations, including single crowns and long bridges produced with and without casts. The restorations are 3D printed using resin at placement angles of 0°, 60°, and 90°. Each group of samples was replicated ten times, resulting in a total of 120 restorations. The Root Mean Square Error (RMSE) value was used to evaluate the surface integrity of the restoration. In addition, the contact space, edge gap, and occlusal space of restorations produced by different processes were recorded. The results indicate that there was no significant difference in the RMSE value of the crown group (p > 0.05). Changing the bridge restoration angle from 0° to 90° resulted in RMSE values increasing by 2.02 times (without casts) and 2.39 times (with casts). Furthermore, the marginal gaps in the crown group were all less than 60 μm, indicating good adaptation. In contrast, the bridge group showed a significant increase in marginal gaps at higher placement angles (p > 0.05). Based on the findings, virtual fabrication without casts does not compromise the accuracy of dental restorations. When the position of the long bridge exceeds 60 degrees, the error will increase. Therefore, designs without casts and parallel placement result in higher accuracy for dental restorations.

From biomimetics to smart materials and 3D technology: Applications in orthodontic bonding, debonding, and appliance design or fabrication

This review covers aspects of orthodontic materials, appliance fabrication and bonding, crossing scientific fields and presenting recent advances in science and technology. Its purpose is to familiarize the reader with developments on these issues, indicate possible future applications of such pioneering approaches, and report the current status in orthodontics. The first section of this review covers shape-memory polymer wires, several misconceptions arising from the recent introduction of novel three-dimensional (3D)-printed aligners (mistakenly termed shape-memory polymers only because they present a certain degree of rebound capacity, as most non-stiff alloys or polymers do), frictionless surfaces enabling resistance-less sliding, self-healing materials for effective handling of fractured plastic/ceramic brackets, self-cleaning materials to minimize microbial attachment or plaque build-up on orthodontic appliances, elastomers with reduced force relaxation and extended stretching capacity to address the problem of inadequate force application during wire-engagement in the bracket slot, biomimetic (non-etching mediated) adhesive attachment to surfaces based on the model of the gecko and the mussel, and command-debond adhesives as options for an atraumatic debonding. This review's second section deals with the recent and largely unsubstantiated application of 3D-printed alloys and polymers in orthodontics and aspects of planning, material fabrication, and appliance design.

Design and Fabrication of a 3D-Printed Microfluidic Immunoarray for Ultrasensitive Multiplexed Protein Detection

Microfluidic technology has revolutionized device fabrication by merging principles of fluid dynamics with technologies from chemistry, physics, biology, material science, and microelectronics. Microfluidic systems manipulate small volumes of fluids to perform automated tasks with applications ranging from chemical syntheses to biomedical diagnostics. The advent of low-cost 3D printers has revolutionized the development of microfluidic systems. For measuring molecules, 3D printing offers cost-effective, time, and ease-of-designing benefits. In this paper, we present a comprehensive tutorial for design, optimization, and validation for creating a 3D-printed microfluidic immunoarray for ultrasensitive detection of multiple protein biomarkers. The target is the development of a point of care array to determine five protein biomarkers for aggressive cancers. The design phase involves defining dimensions of microchannels, reagent chambers, detection wells, and optimizing parameters and detection methods. In this study, the physical design of the array underwent multiple iterations to optimize key features, such as developing open detection wells for uniform signal distribution and a flap for covering wells during the assay. Then, full signal optimization for sensitivity and limit of detection (LOD) was performed, and calibration plots were generated to assess linear dynamic ranges and LODs. Varying characteristics among biomarkers highlighted the need for tailored assay conditions. Spike-recovery studies confirmed the assay's accuracy. Overall, this paper showcases the methodology, rigor, and innovation involved in designing a 3D-printed microfluidic immunoarray. Optimized parameters, calibration equations, and sensitivity and accuracy data contribute valuable metrics for future applications in biomarker analyses.

Aging Processes and Their Influence on the Mechanical Properties of Printable Occlusal Splint Materials

Three-dimensional (3D)-printed occlusal splints are becoming more prevalent in the treatment of tooth substance loss due to their fast and cost-effective production. The purpose of this in vitro study was to investigate whether the mechanical properties (tensile strength-TS, modulus of elasticity in tension-ME, and Vickers hardness-HV) vary between the materials (printed dimethacrylate-based resins: Keyprint KeySplint soft-KEY, Luxaprint Ortho Plus-LUX, V-Print splint-VPR, printed methacrylate-based resins Freeprint splint 2.0-FRE, and milled methacrylate-based material, CLEAR splint-CLE), and the influence of aging processes (extraoral storage conditions and nightly or daily use) was examined. The printed methacrylate-based resins (FRE, LUX, and VPR) had much higher TS (43.7-48.5 MPa compared to 12.3-13.3 MPa), higher ME (2.01-2.37 GPa compared to 0.43-0.72 GPa), and higher HV (11.8-15.0 HV compared to 3.3-3.5 HV) than both of the methacrylate-based resins (KEY and CLE) after the production process. Although the TS, ME, and HV of the printed dimethacrylate resins (FRE, LUX, and VPR) decreased significantly under humid conditions with possibly elevated temperatures (thermocycling as well as 37 °C), these mechanical properties were significantly higher than both methacrylate-based resins (KEY and CLE). Therefore, printed dimethacrylate resins should be used rather than methacrylate-based resins for high expected masticatory forces, low wall thicknesses, or very long wearing times (≥6 months).

Comparative Analysis of the Structural Weights of Fixed Prostheses of Zirconium Dioxide, Metal Ceramic, PMMA and 3DPP Printing Resin-Mechanical Implications

The aim of this study was to determine the mechanical implications of four-unit fixed dental prostheses (FDPs) made of (1) monolithic zirconium dioxide (ZR O2), (2) polymethylmethacrylate (PMMA), (3) metal ceramic (PFM) and (4) impression resin (3DPP).

METHODS

Four groups were studied with eight samples for each material (n: 32). Each structure was weighed, subjected to compressive tests and analyzed using 3D FEA.

RESULTS

PMMA presented the lowest structural weight (1.33 g), followed by 3DPP (1.98 g), ZR O2 (6.34 g) and PFM (6.44 g). In fracture tests, PMMA presented a compressive strength of 2104.73 N and a tension of 351.752 MPa; followed by PFM, with a strength of 1361.48 N and a tension of 227.521 MPa; ZR O2, with a strength of 1107.63 N and a tension of 185.098 MPa; and 3DPP, with a strength of 1000.88 N and a tension of 143.916 MPa. According to 3D FEA, 3DPP presented the lowest degree of deformation (0.001 mm), followed by PFM (0.011 mm), ZR O2 (0.168 mm) and PMMA (1.035 mm).

CONCLUSIONS

The weights of the materials did not have a direct influence on the mean values obtained for strength, stress or strain. Since the performance was related to the tension and forces supported by the structures in critical zones, the importance of considering design factors is clear. In vitro and 3D FEA assays allowed us to simulate different scenarios for the mechanical properties of certain materials before evaluating them clinically. Thus, they can generate predictions that would allow for the design of a better research methodology in future clinical trials.

A Comparison of In Vivo Bone Tissue Generation Using Calcium Phosphate Bone Substitutes in a Novel 3D Printed Four-Chamber Periosteal Bioreactor

Autologous bone replacement remains the preferred treatment for segmental defects of the mandible; however, it cannot replicate complex facial geometry and causes donor site morbidity. Bone tissue engineering has the potential to overcome these limitations. Various commercially available calcium phosphate-based bone substitutes (Novabone®, BioOss®, and Zengro®) are commonly used in dentistry for small bone defects around teeth and implants. However, their role in ectopic bone formation, which can later be applied as vascularized graft in a bone defect, is yet to be explored. Here, we compare the above-mentioned bone substitutes with autologous bone with the aim of selecting one for future studies of segmental mandibular repair. Six female sheep, aged 7-8 years, were implanted with 40 mm long four-chambered polyether ether ketone (PEEK) bioreactors prepared using additive manufacturing followed by plasma immersion ion implantation (PIII) to improve hydrophilicity and bioactivity. Each bioreactor was wrapped with vascularized scapular periosteum and the chambers were filled with autologous bone graft, Novabone®, BioOss®, and Zengro®, respectively. The bioreactors were implanted within a subscapular muscle pocket for either 8 weeks (two sheep), 10 weeks (two sheep), or 12 weeks (two sheep), after which they were removed and assessed by microCT and routine histology. Moderate bone formation was observed in autologous bone grafts, while low bone formation was observed in the BioOss® and Zengro® chambers. No bone formation was observed in the Novabone® chambers. Although the BioOss® and Zengro® chambers contained relatively small amounts of bone, endochondral ossification and retained hydroxyapatite suggest their potential in new bone formation in an ectopic site if a consistent supply of progenitor cells and/or growth factors can be ensured over a longer duration.

A novel technique for CAD-CAM assisted digital ocular prosthesis

There are various techniques available for constructing a custom ocular prosthesis. The present technique report describes a digital workflow for constructing an ocular prosthesis using computed tomography integrated with digital technologies. The outer region of the healthy eyeball was segmented to produce the top surface of the prosthesis, while the contour and bottom surface were segmented from the tissue bed of the anophthalmic socket. The iris position was determined by tracing the optical nerve and confirmed by superimposing the patient's facial scan onto the soft tissue model of the computed tomography. Using these parameters, a standard tessellation language file for the ocular prosthesis was generated and 3D printed. The iris was then printed via UV technology using digital photographs of the patient's contralateral eye; characterization of the sclera and the final layer of clear acrylic resin were done conventionally.

Research progress and clinical translation of three-dimensional printed porous tantalum in orthopaedics

With continuous developments in additive manufacturing technology, tantalum (Ta) metal has been manufactured into orthopaedic implants with a variety of forms, properties and uses by three-dimensional printing. Based on extensive research in recent years, the design, processing and performance aspects of this new orthopaedic implant material have been greatly improved. Besides the bionic porous structure and mechanical characteristics that are similar to human bone tissue, porous tantalum is considered to be a viable bone repair material due to its outstanding corrosion resistance, biocompatibility, bone integration and bone conductivity. Numerous in vitro, in vivo, and clinical studies have been carried out in order to analyse the safety and efficacy of these implants in orthopaedic applications. This study reviews the most recent advances in manufacturing, characteristics and clinical application of porous tantalum materials.

Realistic three-layer head phantom for optically pumped magnetometer-based magnetoencephalography

The advent of optically pumped magnetometer-based magnetoencephalography (OPM-MEG) has introduced new tools for neuroscience and clinical research. As it is still under development, the achievable performance of OPM-MEG remains to be tested, particularly in terms of source localization accuracy, which can be influenced by various factors, including software and hardware aspects. A feasible approach to comprehensively test the performance of the OPM-MEG system is to utilize a phantom that simulates the actual electrophysiological properties of the head while ensuring the precise locations of dipole sources. However, conventional water or dry phantoms can only simulate a single-sphere head model. In this work, a more realistic three-layer phantom was designed and fabricated. The proposed phantom included the scalp, skull, and cortex tissues of the head, as well as the simulated dipole sources. The scalp and cortex tissues were simulated using an electrolyte solution, while the dipole source was constructed from a coaxial cable. All main structures in the phantom were produced using 3D printing techniques, making the phantom easy to manufacture. The fabricated phantom was tested on a 36-channel OPM-MEG system, and the results showed that the dipole source inside the phantom could generate a magnetic field distribution on the scalp that was close to its theoretical values. The average source localization accuracy of 5.51 mm verified the effectiveness of the designed phantom and the performance of our OPM-MEG system. This work provides an effective test platform for OPM-MEG.

IoT-Based Agro-Toolbox for Soil Analysis and Environmental Monitoring

The agricultural sector faces numerous challenges in ensuring optimal soil health and environmental conditions for sustainable crop production. Traditional soil analysis methods are often time-consuming and labor-intensive, and provide limited real-time data, making it challenging for farmers to make informed decisions. In recent years, Internet of Things (IoT) technology has emerged as a promising solution to address these challenges by enabling efficient and automated soil analysis and environmental monitoring. This paper presents a 3D-printed IoT-based Agro-toolbox, designed for comprehensive soil analysis and environmental monitoring in the agricultural domain. The toolbox integrates various sensors for both soil and environmental measurements. By deploying this tool across fields, farmers can continuously monitor key soil parameters, including pH levels, moisture content, and temperature. Additionally, environmental factors such as ambient temperature, humidity, intensity of visible light, and barometric pressure can be monitored to assess the overall health of agricultural ecosystems. To evaluate the effectiveness of the Agro-toolbox, a case study was conducted in an aquaponics floating system with rocket, and benchmarking was performed using commercial tools that integrate sensors for soil temperature, moisture, and pH levels, as well as for air temperature, humidity, and intensity of visible light. The results showed that the Agro-toolbox had an acceptable error percentage, and it can be useful for agricultural applications.

Regenerative Engineering of a Biphasic Patient-Fitted Temporomandibular Joint Condylar Prosthesis

Regenerative medicine approaches to restore the mandibular condyle of the temporomandibular joint (TMJ) may fill an unmet patient need. In this study, a method to implant an acellular regenerative TMJ prosthesis was developed for orthotopic implantation in a pilot goat study. The scaffold incorporated a porous, polycaprolactone-hydroxyapatite (PCL-HAp, 20wt% HAp) 3D printed condyle with a cartilage-matrix-containing hydrogel. A series of material characterizations was used to determine the structure, fluid transport, and mechanical properties of 3D printed PCL-HAp. To promote marrow uptake for cell seeding, a scaffold pore size of 152 ± 68 μm resulted in a whole blood transport initial velocity of 3.7 ± 1.2 mm·s-1 transported to the full 1 cm height. The Young's modulus of PCL was increased by 67% with the addition of HAp, resulting in a stiffness of 269 ± 20 MPa for etched PCL-HAp. In addition, the bending modulus increased by 2.06-fold with the addition of HAp to 470 MPa for PCL-HAp. The prosthesis design with an integrated hydrogel was compared with unoperated contralateral control and no-hydrogel group in a goat model for 6 months. A guide was used to make the condylectomy cut, and the TMJ disc was preserved. MicroCT assessment of bone suggested variable tissue responses with some regions of bone growth and loss, although more loss may have been exhibited by the hydrogel group than the no-hydrogel group. A benchtop load transmission test suggested that the prosthesis was not shielding load to the underlying bone. Although variable, signs of neocartilage formation were exhibited by Alcian blue and collagen II staining on the anterior, functional surface of the condyle. Overall, this study demonstrated signs of functional TMJ restoration with an acellular prosthesis. There were apparent limitations to continuous, reproducible bone formation, and stratified zonal cartilage regeneration. Future work may refine the prosthesis design for a regenerative TMJ prosthesis amenable to clinical translation.

Micron/Submicron Scaled Hierarchical Ti Phosphate/Ti Oxide Hybrid Coating on 3D Printed Scaffolds for Improved Osteointegration

Three-dimensional (3D) printed implants have attracted substantial attention in the field of personalized medicine, but negative impacts on mechanical properties or initial osteointegration have limited their application. To address these problems, we prepared hierarchical Ti phosphate/Ti oxide (TiP-Ti) hybrid coatings on 3D printed Ti scaffolds. The surface morphology, chemical composition, and bonding strength of the scaffolds were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, X-ray diffraction (XRD), and scratch test. In vitro performance was analyzed by colonization and proliferation of rat bone marrow mesenchymal stem cells (BMSCs). In vivo osteointegration of the scaffolds in rat femurs was assessed by micro-CT and histological analyses. The results demonstrated improved cell colonization and proliferation as well as excellent osteointegration obtained by incorporation of our scaffolds with the novel TiP-Ti coating. In conclusion, micron/submicron scaled Ti phosphate/Ti oxide hybrid coatings on 3D printed scaffolds have promising potential in future biomedical applications.

Treatment of Acetabular Bone Defect in Revision of Total Hip Arthroplasty Using 3D Printed Tantalum Acetabular Augment

OBJECTIVE

The treatment of acetabular defects is one of the most difficult challenges of revision of total hip arthroplasty (RTHA), and tantalum is regarded as a promising bone substitute material. This study aims to investigate the effectiveness of 3D printed acetabular augment used in RTHA for the treatment of acetabular bone defect.

METHODS

A retrospective analysis of the clinical data of seven patients who had undergone RTHA was carried out using 3D printed acetabular augment from January 2017 to December 2018. The CT data of the patients were exported to Mimics 21.0 software (Materialise, Leuven, Belgium), and the acetabular bone defect augment were designed, printed and then implanted during operation. The postoperative Harris score, visual analogue scale (VAS) score and prosthesis position were observed to evaluate the clinical outcome. A I-test was used for preoperative and postoperative comparison of the paired-design dataset.

RESULTS

A firm attachment of the bone augment to the acetabulum during operation without any complications was found during the follow-up time 2.8-4.3 years. The VAS score of all patients was found 6.9 ± 1.4 before operation and was 0.7 ± 0.7 at the last follow-up (P ≤ 0.001), and the Harris hip scores, were 31.9 ± 10.3 and 73.3 ± 12.8 before operation, and at the last follow-up (P ≤ 0.001), respectively. Moreover, no loosening sign between the bone defect augment and the acetabulum was observed during the entire implantation period.

CONCLUSION

3D printed acetabular augment is effective in reconstructing the acetabulum following an acetabular bone defect revision, which enhances the hip joint function and eventually makes a satisfactory stable prosthetic.

Clinical application of 3D-printed biodegradable lumbar interbody cage (polycaprolactone/β-tricalcium phosphate) for posterior lumbar interbody fusion

A novel 3D-printed biodegradable cage composed of polycaprolactone (PCL) and beta-tricalcium phosphate (β-TCP) in a mass ratio of 50:50, with stable resorption patterns and mechanical strength has been developed for lumbar interbody fusion. This is a prospective cohort study to evaluate the short- and mid-term safety and efficacy of this biodegradable cage in posterior lumbar interbody fusion (PLIF) surgery. This was a prospective single-arm pilot clinical trial in 22 patients with a follow-up time of 1, 3, 6, and 12 months, postoperatively. Clinical outcomes were assessed using the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and Visual analogue scale (VAS) for leg pain and low back pain. Radiological examination included X-ray, CT scan, and three-dimensional reconstruction to evaluate surgical indications, intervertebral space height (ISH), intervertebral bone fusion and cage degradation. A total of 22 patients was included, with an average age of 53.5 years. Among 22 patients, one patient lost to follow-up and one patient withdrew from the clinical trial because of cage retropulsion. The remaining 20 patients showed significant improvement in clinical and imaging outcomes compared to the preoperative period. The overall mean VAS for back decreased from 5.85 ± 0.99 preoperatively to 1.15 ± 0.86 at the 12-month follow-up (p < .001); the VAS for leg decreased from 5.75 ± 1.11 to 1.05 ± 0.76 (p < .001); the JOA score improved from 13.8 ± 2.64 to 26.45 ± 2.46 (p < .001). The mean intervertebral space height (ISH) increased from 11.01 ± 1.75 mm preoperatively to 12.67 ± 1.89 mm at the 12-month follow-up and the bone fusion reached 95.2% (20/21 disc segments). Partial resorption (inferior to 50% compared with the initial cage size) were found in all cages (21/21). The clinical and radiological assessments showed that the application of 3D-printed biodegradable PCL/β-TCP cages in PLIF yielded satisfactory results at the 12-month follow-up. In the future, long-term clinical observations and controlled clinical trials are required to further validate the safety and efficacy of this novel cage.

Multifunctional Portable System Based on Digital Images for In-Situ Detecting of Environmental and Food Samples

The development of a portable device created by 3D printing for colorimetric and fluorometric measurements is an efficient tool for analytical applications in situ or in the laboratory presenting a wide field of applications in the environmental and food field. This device uses a light-emitting diode (LED) as radiation source and a webcam as a detector. Digital images obtained by the interaction between the radiation source and the sample were analyzed using a programming language developed in Matlab (Mathworks Inc., Natick, MA, USA), which builds the calibration curves in real-time using the RGB colour model. In addition, the entire system is connected to a notebook which serves as an LED and detector power supply without the need for any additional power source. The proposed device was used for the determination in situ of norfloxacin, allura red, and quinine in water and beverages samples, respectively. For the validation of the developed system, the results obtained were compared with a conventional spectrophotometer and spectrofluorometer respectively with a t-test at a 95% confidence level, which provides satisfactory precision and accuracy values.

Mechanical properties and osteointegration of the mesh structure of a lumbar fusion cage made by 3D printing

The currently popular 3D printing makes it possible to produce spatial scaffolds, the main purpose of which is to obtain implants that have favourable mechanical properties to promote cell adhesion. This study aims to prove the influence of changes in selected geometrical parameters of scaffolds, used in intervertebral cages, on the mechanical properties obtained and thus on the osteointegration of the studied constructs with osteoblasts and fibroblasts. The stiffness values and maximum failure force of four modifications to geometric dimensions of the meshes were determined from the intendation test. Adhesion assays were conducted (including gentle pendulum motion) for Balb/3T3 fibroblasts and NHOst osteoblasts. The study revealed that an important geometrical parameter affecting the strength of the mesh is the height (h) of the connection point between arms of successive mesh cells. There was no significant effect of the mesh geometry on the abundance and survival of Balb/3T3 and NHOst cells. At the same time, fibroblasts were more likely to form colonies in the area where there is fusion of mesh cells, as opposed to osteoblasts that were more numerous at vertices of the mesh.

Is three-dimension-printed mesh scaffold an alternative to reconstruct cavity bone defects near joints?

PURPOSE

Reconstruction of cavity bone defects after curettage of benign bone tumours around the joint remains challenging. We designed a novel 3D-printed mesh scaffold as a substitute for bone cement, aiming to support the articular surface, protect the subchondral bone, and reduce complication rates.

METHODS

We retrospectively analyzed seven patients who received curettage and reconstruction using a 3D-printed mesh scaffold between January 2020 and June 2021. Pain and function were evaluated using the 10-cm Visual Analogue Scale (VAS) score and the 1993 version of the Musculoskeletal Tumor Society (MSTS-93) score. Radiographs were used to evaluate articular surface supporting, subchondral bone protection, and complications.

RESULTS

The median functional MSTS-93 and VAS scores were both improved after surgery, and the median 3D-printed mesh scaffold volume was smaller than the median defect volume. Articular surface supporting, subchondral bone preservation, and osteogenesis were observed post-operatively. No related complications were observed during the last follow-up.

CONCLUSIONS

The 3D-printed mesh scaffold provided sufficient mechanical support for the articular surface and protected the subchondral bone. We recommended the 3D-printed mesh structure as an alternative to repair cavity bone defects around joints.

An open-source head-fixation and implant-protection system for mice

Mice are widely used in neuroscience experiments, which often require head-fixation and attachment of skull-mounted hardware. For many experiments, these components must remain intact over weeks to months, ideally with animals group housed. Many labs have designed ad-hoc head-fixation systems, which is an inefficient process. For example, when reinventing these solutions in our lab, we faced challenges with group housing, wherein mice would chew and damage implanted cannulas and electrodes of their cage mates. We performed several non-trivial design iterations to solve this problem, and present the most successful designs as an open-source collection. The designs include a standard mounting headbar compatible with most skull-mounted hardware, a snap-on protective mouse hat (headhat) to prevent mice from chewing the hardware, and a head-fixation station to facilitate common experimental procedures. We provide 3D-printing files, detail vendors and software used to make the components of the system, and provide editable design files for maximum flexibility to individual lab requirements.

The Effect of a Digital Manufacturing Technique, Preparation Taper, and Finish Line Design on the Marginal Fit of Temporary Molar Crowns: An In-Vitro Study

The aim of this study is to investigate the combined effect of a digital manufacturing technique (subtractive vs. additive), preparation taper (10° vs. 20° TOC), and finish line (chamfer vs. shoulder) on the marginal adaptation of temporary crowns following cementation with a compatible temporary cement. Four mandibular first molar typodont teeth were prepared for full coverage crowns with standard 4 mm preparation height as follows: 10° TOC with the chamfer finish line, 10° TOC with the shoulder finish line, 20° TOC with the chamfer finish line and 20° TOC with the shoulder finish line. Each of the four preparation designs were subdivided into two subgroups to receive CAD/CAM milled and 3D-printed crowns (n = 10). A total of 80 temporary crowns (40 CAD/CAM milled and 40 3D-printed) were cemented to their respective die using clear temporary recement in the standard cementation technique. The samples were examined under a stereomicroscope at ×100 magnification following calibration. Linear measurements were performed at seven equidistant points on each axial surface and five equidistant points on each proximal surface. One-way ANOVA analysis and Tukey HSD (Honestly Significance Difference) were performed. The best marginal fit was seen in group 8, while the poorest fit was noted in group 2. Shoulder finish lines and 10° TOC resulted in higher marginal gaps, especially in CAD/CAM milled group. The selection of 3D-printed crowns may provide a better marginal fit within the range of clinical acceptability. Marginal gaps were within clinical acceptability (50 and 120 µm) in all groups except group 2.

Superior fixation strength of coronoid process replacement using individually designed 3D printed prosthesis with curved cemented intramedullary stem

BACKGROUND

Coronoid fractures frequently occur as part of complex elbow injuries and account for 2-15% of the cases with dislocations. Comminuted fractures and non-unions necessitate surgical treatment. Considering the latest technological advancements, the aim of this study was to investigate the fixation strength of coronoid replacement using an individualized 3D printed prosthesis with curved cemented intramedullary stem versus both radial head grafted reconstruction and coronoid fixation.

METHODS

Twenty-four human cadaveric paired forearms were stripped of soft tissue and their CT scanned ulnas were randomized to four groups for coronoid replacement (prosthesis group), radial head grafted reconstruction (radial head group), fixation (fixation group) or no treatment (intact group). The ulnas in all groups except the intact one were osteotomized at 40% of the coronoid height and either replaced with a 3D printed stainless-steel coronoid prosthesis with curved cemented intramedullary stem, individually designed based on the contralateral scan (prosthesis group), reconstructed with an ipsilateral radial head autograft fixed with two anteroposterior screws (radial head group), or coronoid process fixed in situ with two anteroposterior screws (fixation group). All specimens were biomechanically tested under ramped quasi-static axial loading.

RESULTS

Bone mineral density was not significantly different among the groups (p=0.95). Stiffness and failure load in the prosthesis group was significantly higher compared to all other groups (p≤0.04) and in addition it was significantly lower in the fixation group compared to the intact group (=0.03), with no further detected significant differences among the groups (p≥0.72). Absorbed energy to failure in the prosthesis group was significantly more compared to both radial head and fixation groups (p≤0.04) but not versus the intact group. Failure deformation at the osteotomy site was not significantly different among the groups (p=0.26).

CONCLUSIONS

Coronoid process replacement using an anatomically shaped individually designed 3D printed prosthesis with curved cemented intramedullary stem seems to be an effective method to restore the coronoid buttress function under axial loading. This method provides superior fixation strength over both radial head grafted reconstruction and screw fixation.

Fracture toughness and hardness of in-office, 3D-printed ceramic brackets

OBJECTIVES

Three-dimensional (3D) printing technology is a promising manufacturing technique for fabricating ceramic brackets. The aim of this research was to assess fundamental mechanical properties of in-office, 3D printed ceramic brackets.

MATERIALS AND METHODS

3D-printed zirconia brackets, commercially available polycrystalline alumina ceramic brackets (Clarity, 3 M St. Paul, MN) and 3D-printed customized polycrystalline alumina ceramic ones (LightForce™, Burlington, Massachusetts) were included in this study. Seven 3D printed zirconia brackets and equal number of ceramic ones from each manufacturer underwent metallographic grinding and polishing followed by Vickers indentation testing. Hardness (HV) and fracture toughness (K1c) were estimated by measuring impression average diagonal length and crack length, respectively. After descriptive statistics calculation, group differences were analysed with 1 Way ANOVA and Holm Sidak post hoc multiple comparison test at significance level α = .05.

RESULTS

Statistically significant differences were found among the materials tested with respect to hardness and fracture toughness. The 3D-printed zirconia proved to be less hard (1261 ± 39 vs 2000 ± 49 vs 1840 ± 38) but more resistant to crack propagation (K1c = 6.62 ± 0.61 vs 5.30 ± 0.48 vs 4.44 ± 0.30 MPa m^1/2 ) than the alumina brackets (Clarity and Light Force respectivelty). Significant differences were observed between the 3D printed and the commercially available polycrystalline alumina ceramic brackets but to a lesser extent.

CONCLUSIONS

Under the limitations of this study, the 3D printed zirconia bracket tested is characterized by mechanical properties associated with advantageous orthodontic fixed appliances traits regarding clinically relevant parameters.

Three-dimensional-printed porous prosthesis for the joint-sparing reconstruction of the proximal humeral tumorous defect

Background: Tumorous bone defect reconstructions of the proximal humerus with joint sparing is a challenge. Numerous reconstruction methods have been proposed but the proximal residual humerus is commonly sacrificed because of its extremely short length. To preserve the proximal humerus and improve clinical outcomes, we designed a three-dimensional (3D) printed uncemented prosthesis with a porous structure to treat tumorous bone defects of the proximal humerus. Methods: Our analysis included seven patients treated between March 2018 and July 2019. A 3D model was established, and related data were obtained, including the diameter of the humeral head, the resection length, and the residual length. A prosthesis was designed and fabricated based on these data. Functional and oncologic outcomes were recorded, and complications and osseointegration were evaluated. Results: The mean age of the patients was 20.3 years, and the median follow-up period was 26 months. The lengths of the residual proximal humerus were 17.9 mm on average. All the patients had preserved humeral heads and most of the rotator cuff was intact. The average postoperative range of motion (ROM) of the affected shoulder was 83.8°; flexion was 82.5°, extension was 43.8°, and adduction was 16.3°. The average Musculoskeletal Tumor Society score (MSTS) was 94.3%. Good osseointegration was observed on the interface between the bone and prosthesis. Conclusion: A 3D printed porous prosthesis with cone-like structures successfully achieved joint-sparing reconstruction of proximal humeral tumorous defects with satisfying functional outcomes. The preservation of the rotator cuff and humeral head plays an essential role in the function of the shoulder joint.

High porosity 3D printed titanium mesh allows better bone regeneration

BACKGROUND

Most patients with insufficient bone mass suffer from severe horizontal or vertical bone defects in oral implant surgery. The purpose of this study was to compare the bone regeneration effects of titanium meshes with different porosity in the treatment of bone defects.

METHODS

Nine beagle dogs were equally divided into three groups based on execution time. Three months after the extraction of the first to fourth premolars of the mandible, three bone defects were randomly made in the mandible. Bone particles and three kinds of three-dimensional (3D) printed titanium nets with different porosities (low porosity group (LP), 55%; medium porosity group (MP), 62%; and high porosity group (HP), 68%) were replanted in situ. The beagles were killed 4, 8, and 12 weeks after surgery. Formalin-fixed specimens were embedded in acrylic resin. The specimens were stained with micro-CT, basic fuchsin staining, and toluidine blue staining.

RESULTS

Micro-CT analysis showed that the trabecular thickness, trabecular number, and bone volume fraction of the HP group were higher than those of the other two groups. Moreover, the trabecular separation of the HP group decreased slightly and was lower than that of the MP and LP groups. Histological staining analysis showed that the trabecular number in the HP group was higher than in the other two groups at 8 and 12 weeks, and the bone volume fraction of the HP was higher than that in the other two groups at 12 weeks. Moreover, the trabecular thickness of the MP was higher than that of the LP group at 12 weeks and the trabecular separation was lower in the HP group at 4 and 8 weeks. The differences were statistically significant (p < 0.05).

CONCLUSION

A 3D printed titanium mesh with HP in a certain range may have more advantages than a titanium mesh with LP in repairing large bone defects.

Designing and making an open source, 3D-printed, punctal plug with drug delivery system

With the advancement in the study of keratoconjunctivitis sicca and the scope of its treatment, punctal plugs are being widely used for the therapeutic management of dry eye disease. With the emergence of 3D printing in medicine, 3D printing of punctal plugs that have an inbuilt drug delivery system and also that can be personalized from patient to patient according to their punctum size can be a great therapeutic option. Another benefit of the device is that its printing takes a short period of time and is cost-effective. This study aimed at making an open source design and 3D printing an efficient model of a punctal plug with an inbuilt drug delivery system that can be eventually used for the treatment of various ocular diseases that require frequent drug instillation or blockage of the nasolacrimal pathway. The 3D design for the punctal plug was made using the open source application, FreeCAD, and slicing was done using the application ChituBox. After that, the plugs were printed using the LCD printer Crealty LD-002R. The material used was resin that was compatible with the Crealty LD-002R. Punctal plugs with satisfactory results were printed using the LCD printer. The punctal plugs showed suitable structure and were also easily reproduced in the 3D printer without any complications or setbacks.

FeS2-incorporated 3D PCL scaffold improves new bone formation and neovascularization in a rat calvarial defect model

199Three-dimensional (3D) scaffolds composed of various biomaterials, including metals, ceramics, and synthetic polymers, have been widely used to regenerate bone defects. However, these materials possess clear downsides, which prevent bone regeneration. Therefore, composite scaffolds have been developed to compensate these disadvantages and achieve synergetic effects. In this study, a naturally occurring biomineral, FeS₂, was incorporated in PCL scaffolds to enhance the mechanical properties, which would in turn influence the biological characteristics. The composite scaffolds consisting of different weight fractions of FeS₂ were 3D printed and compared to pure PCL scaffold. The surface roughness (5.77-fold) and the compressive strength (3.38-fold) of the PCL scaffold was remarkably enhanced in a dose-dependent manner. The in vivo results showed that the group with PCL/ FeS₂ scaffold implanted had increased neovascularization and bone formation (2.9-fold). These results demonstrated that the FeS₂ incorporated PCL scaffold might be an effective bioimplant for bone tissue regeneration.

Validation of a three-dimensional printed pediatric middle ear model for endoscopic surgery training

Objective

The purpose of this study is to assess the anatomical appropriateness of a three-dimensional (3D) printed pediatric middle ear model with a replaceable middle ear unit as an endoscopic ear surgery (EES) simulator.

Methods

Single-blinded, prospective, proof-of-concept study conducted in a simulation operative suite. A simulator was developed through segmentation of source images and multi-material 3D printing. Subjects were asked to point to seven anatomical sites before and after a short anatomy presentation of a human middle ear photograph. They also filled out a survey about the feasibility of the model. Outcome variables included survey scores, pre-anatomy lesson (PreAL) and post-anatomy lesson (PostAL) quiz scores.

Results

There were 24 participants (19 residents, 1 fellow, and 4 attendings), none with self-reported proficiency in EES. The PreAL mean score was 4.42 and PostAL quiz mean score was 5.32 (average improvement of 43% [CI = 17%-70%]; p = .003). The higher the level of training, the higher the PreAL scores (0.55 points per year of training; p = .004). The subspecialty (otology, other, in-training) was also associated with the PreAL scores (p = .004). Total survey score means were 22.8 (out of 30).

Conclusion

The results of our study suggest that our model has adequate anatomical high fidelity to mimic a real, pediatric temporal bone for EES. As 3D printing technologies continue to advance, the quality of ear models has the potential to provide improved surgical training for pediatric EES.

Level of Evidence

4.

5G-Assisted Remote Guidance in Laparoscopic Simulation Training Based on 3D Printed Dry Lab Models

This is a pilot study to assess the utility of applying 5G-assisted remote guidance in laparoscopic simulation training. A single trainee of a junior surgeon was recruited to complete three steps of tasks including basic task 1, basic task 2, and model task, and the performance was recorded and evaluated. The operator completed each task three times. Except for basic task 1, all tasks were remotely guided by a more experienced surgeon using 5G technology. Tasks completion time and a 30-point objective structured assessment of technical skills (OSATS) score were utilized to assess the results of simulation training. All remote guidance processes were successfully completed without significant network latency. Through basic task 1, the operator quickly became familiar with the trained laparoscopic instruments. For basic task 2, OSATS scores increased from 16 to 24 points, and completion time decreased from 1500 to 986 s after training under 5G-assisted remote guidance. For model tasks, OSATS scores increased from 15 to 26 points, and completion time decreased from 1734 to 1142 s. This is a novel mode of laparoscopic simulation training to increase the convenience of training. Perhaps in the near future, surgeons can simulate difficult operations at home or in the office, and accurately grasp the possible situations that may occur in actual operations in advance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12262-022-03590-2.

Fabrication of 3D Printed poly(lactic acid) strut and wet-electrospun cellulose nano fiber reinforced chitosan-collagen hydrogel composite scaffolds for meniscus tissue engineering

The main goal of the study was to produce chitosan-collagen hydrogel composite scaffolds consisting of 3D printed poly(lactic acid) (PLA) strut and nanofibrous cellulose for meniscus cartilage tissue engineering. For this purpose, first PLA strut containing microchannels was incorporated into cellulose nanofibers and then they were embedded into chitosan-collagen matrix to obtain micro- and nano-sized topographical features for better cellular activities as well as mechanical properties. All the hydrogel composite scaffolds produced by using three different concentrations of genipin (0.1, 0.3, and 0.5%) had an interconnected microporous structure with a swelling ratio of about 400% and water content values between 77 and 83% which is similar to native cartilage extracellular matrix. The compressive strength of all the hydrogel composite scaffolds was found to be similar (∼32 kPa) and suitable for cartilage tissue engineering applications. Besides, the hydrogel composite scaffold comprising 0.3% (w/v) genipin had the highest tan δ value (0.044) at a frequency of 1 Hz which is around the walking frequency of a person. According to the in vitro analysis, this hydrogel composite scaffold did not show any cytotoxic effect on the rabbit mesenchymal stem cells and enabled cells to attach, proliferate and also migrate through the inner area of the scaffold. In conclusion, the produced hydrogel composite scaffold holds great promise for meniscus tissue engineering.

PiRamid: A compact Raspberry Pi imaging box to automate small-scale time-lapse digital analysis, suitable for laboratory and field use

Digital imaging permits the quantitation of many experiments, such as microbiological growth assays, but laboratory digital imaging systems can be expensive and too specialised. The Raspberry Pi camera platform makes automated, controlled imaging affordable with accessible customisation. When combined with open source software and open-source 3D printed hardware, the control over image quality and capture of this platform permits the rapid development of novel instrumentation. Here we present "PiRamid", a compact, portable, and inexpensive enclosure for autonomous imaging both in the laboratory and in the field. The modular three-piece 3D printed design makes it easy to incorporate different camera systems or lighting configurations (e.g., single wavelength LED for fluorescence). The enclosed design allows complete control of illumination unlike a conventional digital camera or smartphone, on a tripod or handheld, under ambient lighting. The stackable design permits rapid sample addition or camera focus adjustment, with a corresponding change in magnification and resolution. The entire unit is small enough to fit within a microbiological incubator, and cheap enough (∼£100) to scale out for larger parallel experiments. Simply, Python scripts fully automate illumination and image capture for small-scale experiments with an ∼110×85 mm area at 70-90 µm resolution. We demonstrate the versatility of PiRamid by capturing time-resolved, quantitative image data for a wide range of assays. Bacterial growth kinetics was captured for conventional microbiology (agar Petri dishes), 3D printed custom microbiology labware and microfluidic microbiology. To illustrate application beyond microbiology, we demonstrate time-lapse imaging of crystal growth and degradation of salad leaves. Minor modifications permit epi-illumination by addition of a LED ring to the camera module. We conclude that PiRamid permits inexpensive digital capture and quantitation of a wide range of experiments by time-lapse imaging to simplify both laboratory and field imaging.

Long-Range Wireless System for U-Value Assessment Using a Low-Cost Heat Flux Sensor

The present study exposes an economical and easy-to-use system to assess the heat transfer in building envelopes by determining the U-value. Nowadays these systems require long wires and a host to collect and process the data. In this work, a multi-point system for simultaneous heat flux measurement has been proposed. The aim is to reduce the long measurement time and the cost of thermal isolation evaluations in large buildings. The system proposed consists of a low-cost 3D-printed heat flux sensor integrated with a LoRa transceiver and two temperature sensors. The heat flux (HF) sensor was compared and calibrated with a commercial HF sensor from the Fluxteq brand.

Fabrication And In Vitro Evaluation Of 3D Printed Porous Silicate Substituted Calcium Phosphate Scaffolds For Bone Tissue Engineering

Silicate-substituted calcium phosphate (Si-CaP) ceramics, alternative materials for autogenous bone grafting, exhibit excellent osteoinductivity, osteoconductivity, biocompatibility and biodegradability; thus, they have been widely used for treating bone defects. However, the limited control over the spatial structure and weak mechanical properties of conventional Si-CaP ceramics hinder their wide application. Here, we used digital light processing (DLP) printing technology to fabricate a novel porous 3D printed Si-CaP scaffold to enhance the scaffold properties. Scanning electron microscopy, compression tests, and computational fluid dynamics simulations of the 3D printed Si-CaP scaffolds revealed a uniform spatial structure, appropriate mechanical properties, and effective interior permeability. Furthermore, compared to Si-CaP groups, 3D printed Si-CaP groups exhibited sustained release of silicon (Si), calcium (Ca) and phosphorus (P) ions. Furthermore, 3D printed Si-CaP groups had more comprehensive and persistent osteogenic effects due to increased osteogenic factor expression and calcium deposition. Our results show that the 3D printed Si-CaP scaffold successfully improved bone marrow mesenchymal stem cell (BMSCs) adhesion, proliferation and osteogenic differentiation and possessed a distinct apatite mineralization ability. Overall, with the help of DLP printing technology, Si-CaP ceramic materials facilitate the fabrication of ideal bone tissue engineering scaffolds with essential elements, providing a promising approach for bone regeneration. This article is protected by copyright. All rights reserved.

Development and Validation of an HPLC-UV Method for the Dissolution Studies of 3D-Printed Paracetamol Formulations in Milk-Containing Simulated Gastrointestinal Media

Herein, a simple and rapid HPLC method for the determination of paracetamol milk-containing biorelevant media is proposed. The separation of the analyte from the milk-containing biorelevant media was accomplished isocratically using a mobile phase containing 25 mM phosphate buffer (pH = 3.0) and methanol, 80:20, v/v at a flow rate of 1 mL min⁻¹. Following a protein precipitation-based sample clean-up, a thorough investigation of the effect of the precipitation reagent (methanol, acetonitrile, 10% v/v trifluoroacetic acid solution) on the analyte recovery was performed. The matrix effect was assessed in each biorelevant medium by comparing the slopes of the calibration curves of aqueous and matrix-matched calibration curves. The method was comprehensively validated using the accuracy profiles. The β-expectation tolerance intervals did not exceed the acceptance criteria of ±15%, meaning that 95% of future results will be included in the defined bias limits. The relative bias ranged between −4.5 and +3.9% for all analytes, while the RSD values for repeatability and intermediate precision were less than 2.7% and 3.0%, respectively. The achieved limit of detection (LOD) was 0.02 μg mL⁻¹ and the lower limits of quantitation (LLOQ) were established as 10 μg mL⁻¹, which corresponded to 2% of the highest expected concentration of paracetamol. The proposed scheme was utilized for the determination of paracetamol in dissolution studies of its 3D-printed formulation in milk-containing biorelevant media.

Repair of distal fibular and lateral malleolus defects with individualized 3D-printed titanium alloy prosthesis: The first case report from China

Introduction and importance

This case report describes the reconstruction of the traumatic distal fibular and lateral malleolus defects with a novel method of using individualized 3D printed titanium prosthesis for the first time.

Case presentation

A 63-year-old male farmer was hospitalized in emergency because of open injury and distal fibular and lateral malleolus defects in the left leg caused by a car accident. 3 months after debridement and latissimus dorsi muscle flap transplantation and skin graft operation, the patient re-hospitalized because of distal fibular and lateral malleolus defect and local pain. We examined the bilateral ankle joint with three-dimensional CT, obtained data about the missing left distal fibular and lateral malleolus through the mirror principle. The corresponding titanium alloy prosthesis then was designed and printed using a 3D metal printer. The patient had no obvious contraindication for surgery, so the prosthesis was surgically implanted. The patient was followed up for 2 years. There was no discomfort at the surgical site. The function of the operated ankle was satisfied by the patient, the AOFAS (American Orthopaedic Foot & Ankle Society) score was 85 (Kitaoka et al., 1994 [1]).

Clinical discussion

Individualized 3D printed titanium alloy prosthesis consistent with the anatomical structure of lost distal fibula and lateral malleolus. The proximal end of the prosthesis was designed with four nail holes to install screws to fix the fibula together with it. The lower tibiofibular and talofibular joint surfaces of the prosthesis were designed smoothly. In order to improve the stability of the lower tibiofibular joint, anchors were placed at the attachment of the anterior and posterior tibiofibular ligaments to reconstruct these ligaments.

Conclusion

The structure and function of the reconstructed distal fibular and the lateral malleous were close to normal. Individualized 3D printed prosthesis might have considerable advantages over traditional treatment methods. The individualized 3D printed titanium alloy prosthesis provides a new method for the repair and reconstruction of similar bone defects. The use of 3D printed prosthesis for surgical repair needs to be further examined in the future through long-term follow-up studies and in more cases.

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Individualized 3D printed prosthesis of traumatic distal fibular and lateral malleolus defects was initially designed.

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This individualized prosthesis is consistent with the anatomical structure of lost distal fibula and lateral malleolus.

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The structure and function of the defect site could be reconstructed after prosthesis implantation.

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Individualized 3D printed titanium alloy prosthesis provides a new method for the reconstruction of similar bone defects.

Effect of denture cleansers on the surface properties and color stability of 3D Printed denture base materials

OBJECTIVES

To evaluate the effect of denture cleansers on surface roughness, hardness and color stability of 3D-printed resins compared to heat-polymerized resins.

METHODS

Acrylic specimens (N=160) were prepared using one heat-polymerized (HP) and three 3D-printed denture base resins. Specimens per material were randomly divided into four groups (n = 10) according to immersion solutions as follows: distilled water (DW), sodium hypochlorite (NaOCl), effervescent tablet 1 or effervescent tablet 2. Color changes (∆E) were measured using a spectrophotometer. Surface roughness (Ra, µm) and microhardness were evaluated. The results were analyzed using one- and three-way ANOVA with Tukey's post hoc test (α = 0.05).

RESULTS

After 360 days of cleaning protocols, we observed a significant increase in the surface roughness of tested materials (P<0.001). Hardness values significantly decreased in all groups (P<0.001), except HP and ND specimens, cleaned with effervescent tablet 1 (P>0.05) and AS specimens with effervescent tablet 2 (P=0.051). According to the National Bureau of Standards (NBS) score, all denture base specimens had 'perceivable' to 'extremely marked' color change after immersion in NaOCl, while immersion in effervescent tablets 1 and 2 resulted in a 'slight' to 'marked' color change.

CONCLUSION

3D-printed denture bases exhibited changes in surface roughness, hardness and color of 3D-printed dentures similar to HP denture base material. The use of denture cleansers resulted in a time-dependent increase in surface roughness and a decrease in hardness. The color change was significant with NaOCl, while effervescent denture cleansers produced a minimal color difference.

CLINICAL SIGNIFICANCE

Denture cleansers seem to influence surface properties over time. The degree of impact is mainly dependent on the type of cleanser selected, regardless of the type of denture base material.

A Hybrid 3D Printed Hand Prosthesis Prototype Based on sEMG and a Fully Embedded Computer Vision System

This study presents a new approach for an sEMG hand prosthesis based on a 3D printed model with a fully embedded computer vision (CV) system in a hybrid version. A modified 5-layer Smaller Visual Geometry Group (VGG) convolutional neural network (CNN), running on a Raspberry Pi 3 microcomputer connected to a webcam, recognizes the shape of daily use objects, and defines the pattern of the prosthetic grasp/gesture among five classes: Palmar Neutral, Palmar Pronated, Tripod Pinch, Key Grasp, and Index Finger Extension. Using the Myoware board and a finite state machine, the user's intention, depicted by a myoelectric signal, starts the process, photographing the object, proceeding to the grasp/gesture classification, and commands the prosthetic motors to execute the movements. Keras software was used as an application programming interface and TensorFlow as numerical computing software. The proposed system obtained 99% accuracy, 97% sensitivity, and 99% specificity, showing that the CV system is a promising technology to assist the definition of the grasp pattern in prosthetic devices.

Early revision events among patients with a three dimensional (3D) printed cellular titanium or PEEK (polyetheretherketone) spinal cage for single-level lumbar spinal fusion

INTRODUCTION

Three-dimensional (3D) printed spinal cages are a new design of intervertebral body fusion devices. Clinical data on these devices are limited. The objective of this study was to describe six-month events for a new and older cage design.

METHODS

A retrospective, descriptive cohort study of patients that received a 3D-printed-titanium or PEEK (polyetheretherketone) cage with single-level lumbar fusion was performed using a United States hospital-based database. Outcomes evaluated were device-related revision and non-device related reoperation events 6 months after lumbar fusion. The 3D-printed-titanium and PEEK groups were propensity-score matched. Both unmatched and matched groups were descriptively analyzed. There were 93 and 2,082 patients with a 3D-printed-titanium and PEEK cage that met study criteria. The sample size was 93 patients per group after matching.

RESULTS

There were no occurrences of revisions in the 3D-printed-titanium and eleven occurrences in the PEEK group before matching; PEEK had no occurrences of revision after matching. Ten total reoperation events were identified.

DISCUSSION

Our findings suggest occurrence of 6-month revision or reoperation is similar or lower for both cages than reported in published literature. The low occurrence of early events for 3D-printed-titianium cages is promising. Further, real-world studies on 3D-printed cages are warranted.

Effects of Heat-Treatment on Tensile Behavior and Dimension Stability of 3D Printed Carbon Fiber Reinforced Composites

This work investigated the effects of heat treatment on the tensile behavior of 3D-printed high modules carbon fiber-reinforced composites. The manufacturing of samples with different material combinations using polylactic acid (PLA) reinforced with 9% carbon fiber (PLACF), acrylonitrile butadiene styrene (ABS) reinforced with 9% carbon fiber (ABSCF) were made. This paper addresses the tensile behavior of different structured arrangements at different% of densities between two kinds of filaments. The comparison of the tensile behavior between heat treated and untreated samples. The results showed that heat treatment improves the tensile properties of samples by enhancing the bonding of filament layers and by reducing the porosity content. At all structure specifications, the rectilinear pattern gives higher strength of up to 33% compared with the Archimedean chords pattern. Moreover, there is a limited improvement in the tensile strength and modulus of elasticity values for the samples treated at low heat-treatment temperature. The suggested methodology to evaluate the tensile behavior of the pairs of materials selected is innovative and could be used to examine sandwich designs as an alternative to producing multi-material components using inexpensive materials.