Three-Dimensional (3D) Printed Microneedles for Microencapsulated Cell Extrusion

Cell-hydrogel based therapies offer great promise for wound healing. The specific aim of this study was to assess the viability of human hepatocellular carcinoma (HepG2) cells immobilized in atomized alginate capsules (3.5% (w/v) alginate, d = 225 µm ± 24.5 µm) post-extrusion through a three-dimensional (3D) printed methacrylate-based custom hollow microneedle assembly (circular array of 13 conical frusta) fabricated using stereolithography. With a jetting reliability of 80%, the solvent-sterilized device with a root mean square roughness of 158 nm at the extrusion nozzle tip (d = 325 μm) was operated at a flowrate of 12 mL/min. There was no significant difference between the viability of the sheared and control samples for extrusion times of 2 h (p = 0.14, α = 0.05) and 24 h (p = 0.5, α = 0.05) post-atomization. Factoring the increase in extrusion yield from 21.2% to 56.4% attributed to hydrogel bioerosion quantifiable by a loss in resilience from 5470 (J/m3) to 3250 (J/m3), there was no significant difference in percentage relative payload (p = 0.2628, α = 0.05) when extrusion occurred 24 h (12.2 ± 4.9%) when compared to 2 h (9.9 ± 2.8%) post-atomization. Results from this paper highlight the feasibility of encapsulated cell extrusion, specifically protection from shear, through a hollow microneedle assembly reported for the first time in literature.

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Dimensional Accuracy of Dental Models for Three-Unit Prostheses Fabricated by Various 3D Printing Technologies

Materials ◽

10.3390/ma14061550 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1550

Author(s):

Soo-Yeon Yoo ◽

Seong-Kyun Kim ◽

Seong-Joo Heo ◽

Jai-Young Koak ◽

Joung-Gyu Kim

Keyword(s):

Surface Roughness ◽

Three Dimensional ◽

Dimensional Accuracy ◽

3D Analysis ◽

Digital Light Processing ◽

Test Models ◽

Reference File ◽

Significant Difference ◽

Jet Printing ◽

3D Printed

Previous studies on accuracy of three-dimensional (3D) printed model focused on full arch measurements at few points. The aim of this study was to examine the dimensional accuracy of 3D-printed models which were teeth-prepped for three-unit fixed prostheses, especially at margin and proximal contact areas. The prepped dental model was scanned with a desktop scanner. Using this reference file, test models were fabricated by digital light processing (DLP), Multi-Jet printing (MJP), and stereo-lithography apparatus (SLA) techniques. We calculated the accuracy (trueness and precision) of 3D-printed models on 3D planes, and deviations of each measured points at buccolingual and mesiodistal planes. We also analyzed the surface roughness of resin printed models. For overall 3D analysis, MJP showed significantly higher accuracy (trueness) than DLP and SLA techniques; however, there was not any statistically significant difference on precision. For deviations on margins of molar tooth and distance to proximal contact, MJP showed significantly accurate results; however, for a premolar tooth, there was no significant difference between the groups. 3D color maps of printed models showed contraction buccolingually, and surface roughness of the models fabricated by MJP technique was observed as the lowest. The accuracy of the 3D-printed resin models by DLP, MJP, and SLA techniques showed a clinically acceptable range to use as a working model for manufacturing dental prostheses

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Investigation of three-dimensional printing materials for printing aorta model replicating Type B aortic dissection

Current Medical Imaging Formerly Current Medical Imaging Reviews ◽

10.2174/1573405617666210218102046 ◽

2021 ◽

Vol 17 ◽

Author(s):

Chia-An Wu ◽

Andrew Squelch ◽

Zhonghua Sun

Keyword(s):

3D Printing ◽

Aortic Dissection ◽

Three Dimensional ◽

Ct Images ◽

Patient Specific ◽

Type B ◽

Type B Aortic Dissection ◽

Ct Attenuation ◽

Significant Difference ◽

3D Printed

Aim: To determine a printing material that has both elastic property and radiology equivalence close to real aorta for simulation of endovascular stent graft repair of aortic dissection. Background: With the rapid development of three-dimensional (3D) printing technology, a patient-specific 3D printed model is able to help surgeons to make better treatment plan for Type B aortic dissection patients. However, the radiological properties of most 3D printing materials have not been well characterized. This study aims to investigate the appropriate materials for printing human aorta with mechanical and radiological properties similar to the real aortic computed tomography (CT) attenuation. Objective: Quantitative assessment of CT attenuation of different materials used in 3D printed models of aortic dissection for developing patient-specific 3D printed aorta models to simulate type B aortic dissection. Method: A 25-mm length of aorta model was segmented from a patient’s image dataset with diagnosis of type B aortic dissection. Four different elastic commercial 3D printing materials, namely Agilus A40 and A50, Visijet CE-NT A30 and A70 were selected and printed with different hardness. Totally four models were printed out and conducted CT scanned twice on a 192-slice CT scanner using the standard aortic CT angiography protocol, with and without contrast inside the lumen.Five reference points with region of interest (ROI) of 1.77 mm2 were selected at the aortic wall and intimal flap and their Hounsfield units (HU) were measured and compared with the CT attenuation of original CT images. The comparison between the patient’s aorta and models was performed through a paired-sample t-test to determine if there is any significant difference. Result: The mean CT attenuation of aortic wall of the original CT images was 80.7 HU. Analysis of images without using contrast medium showed that the material of Agilus A50 produced the mean CT attenuation of 82.6 HU, which is similar to that of original CT images. The CT attenuation measured at images acquired with other three materials was significantly lower than that of original images (p<0.05). After adding contrast medium, Visijet CE-NT A30 had an average CT attenuation of 90.6 HU, which is close to that of the original images with statistically significant difference (p>0.05). In contrast, the CT attenuation measured at images acquired with other three materials (Agilus A40, A50 and Visiject CE-NT A70) was 129 HU, 135 HU and 129.6 HU, respectively, which is significantly higher than that of original CT images (p<0.05). Conclusion: Both Visijet CE-NT and Agilus have tensile strength and elongation close to real patient’s tissue properties producing similar CT attenuation. Visijet CE-NT A30 is considered the appropriate material for printing aorta to simulate contrast-enhanced CT imaging of type B aortic dissection. Due to lack of body phantom in the experiments, further research with simulation of realistic anatomical body environment should be conducted.

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Control-Based 4D Printing: Adaptive 4D-Printed Systems

Applied Sciences ◽

10.3390/app10093020 ◽

2020 ◽

Vol 10 (9) ◽

pp. 3020 ◽

Cited By ~ 3

Author(s):

Ali Zolfagharian ◽

Akif Kaynak ◽

Mahdi Bodaghi ◽

Abbas Z. Kouzani ◽

Saleh Gharaie ◽

...

Keyword(s):

Three Dimensional ◽

Advanced Manufacturing ◽

Wearable Electronics ◽

Stimuli Responsive ◽

4D Printing ◽

Control Units ◽

Printed Sensors ◽

3D Printed ◽

Dynamic Structures ◽

And Control

Building on the recent progress of four-dimensional (4D) printing to produce dynamic structures, this study aimed to bring this technology to the next level by introducing control-based 4D printing to develop adaptive 4D-printed systems with highly versatile multi-disciplinary applications, including medicine, in the form of assisted soft robots, smart textiles as wearable electronics and other industries such as agriculture and microfluidics. This study introduced and analysed adaptive 4D-printed systems with an advanced manufacturing approach for developing stimuli-responsive constructs that organically adapted to environmental dynamic situations and uncertainties as nature does. The adaptive 4D-printed systems incorporated synergic integration of three-dimensional (3D)-printed sensors into 4D-printing and control units, which could be assembled and programmed to transform their shapes based on the assigned tasks and environmental stimuli. This paper demonstrates the adaptivity of these systems via a combination of proprioceptive sensory feedback, modeling and controllers, as well as the challenges and future opportunities they present.

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Three-Dimensional Printing of Curcumin-Loaded Biodegradable and Flexible Scaffold for Intracranial Therapy of Glioblastoma Multiforme

Pharmaceutics ◽

10.3390/pharmaceutics13040471 ◽

2021 ◽

Vol 13 (4) ◽

pp. 471

Author(s):

Ruixiu Li ◽

Yunmei Song ◽

Paris Fouladian ◽

Mohammad Arafat ◽

Rosa Chung ◽

...

Keyword(s):

Drug Delivery ◽

Glioblastoma Multiforme ◽

Drug Delivery System ◽

Delivery System ◽

Treatment Options ◽

Three Dimensional ◽

Great Promise ◽

Porous Scaffolds ◽

3D Printed

A novel drug delivery system preventing Glioblastoma multiforme (GBM) recurrence after resection surgery is imperatively required to overcome the mechanical limitation of the current local drug delivery system and to offer personalised treatment options for GBM patients. In this study, 3D printed biodegradable flexible porous scaffolds were developed via Fused Deposition Modelling (FDM) three-dimensional (3D) printing technology for the local delivery of curcumin. The flexible porous scaffolds were 3D printed with various geometries containing 1, 3, 5, and 7% (w/w) of curcumin, respectively, using curcumin-loaded polycaprolactone (PCL) filaments. The scaffolds were characterised by a series of characterisation studies and in vitro studies were also performed including drug release study, scaffold degradation study, and cytotoxicity study. The curcumin-loaded PCL scaffolds displayed versatile spatiotemporal characteristics. The polymeric scaffolds obtained great mechanical flexibility with a low tensile modulus of less than 2 MPa, and 4 to 7-fold ultimate tensile strain, which can avoid the mechanical mismatch problem of commercially available GLIADEL wafer with a further improvement in surgical margin coverage. In vitro release profiles have demonstrated the sustained release patterns of curcumin with adjustable release amounts and durations up to 77 h. MTT study has demonstrated the great cytotoxic effect of curcumin-loaded scaffolds against the U87 human GBM cell line. Therefore, 3D printed curcumin-loaded scaffold has great promise to provide better GBM treatment options with its mechanical flexibility and customisability to match individual needs, preventing post-surgery GBM recurrence and eventually prolonging the life expectancy of GBM patients.

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Design, Analysis, Experimentation, and Control of a Partially Compliant Bistable Mechanism

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4045151 ◽

2019 ◽

Vol 142 (1) ◽

Author(s):

Ayse Tekes ◽

Hongkuan Lin ◽

Kevin McFall

Keyword(s):

Dynamic Response ◽

Elliptic Integral ◽

Three Dimensional ◽

Design Analysis ◽

Lumped Parameter Model ◽

Lumped Parameter ◽

Rigid Body Model ◽

3D Printed ◽

Bistable Mechanism ◽

And Control

Abstract This study presents the design analysis and development of a novel partially compliant bistable mechanism. Motion behavior dependence on links and relative angles are analyzed, lumped parameter model is derived, mechanism parts including the compliant members are three-dimensional (3D) printed and a state feedback controller is implemented so that the slider follows a well-defined trajectory if designed as an actuator. The proposed mechanism consists of initially straight, large deflecting fixed-pinned compliant links, rigid links, and a sliding mass. Dynamic response of the mechanism is studied using elliptic integral solutions, pseudo rigid body model (PRBM), vector closure loop equations and Elliptic integrals. Nonlinear model is simulated in matlab simulink using fourth‐order Runge‐Kutta algorithms. The research emphasizes on the realization and dynamic response of the mechanism and the trajectory control of the slider so that the slider can be kept constant at specified distances resulting a dwell motion if designed as a linear actuator.

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Design and Manufacturing of 3D Printed Foods With User Validation

Volume 6: 25th Design for Manufacturing and the Life Cycle Conference (DFMLC) ◽

10.1115/detc2020-22462 ◽

2020 ◽

Author(s):

Stefania Chirico Scheele ◽

Martin Binks ◽

Paul F. Egan

Keyword(s):

Additive Manufacturing ◽

User Satisfaction ◽

Three Dimensional ◽

User Preferences ◽

User Preference ◽

Great Promise ◽

High Fidelity ◽

Standard Design ◽

3D Printed ◽

Overhang Angle

Abstract Additive manufacturing is becoming widely practical for diverse engineering applications, with emerging approaches showing great promise in the food industry. From the realization of complex food designs to the automated preparation of personalized meals, 3D printing promises many innovations in the food manufacturing sector. However, its use is limited due to the need to better understand manufacturing capabilities for different food materials and user preferences for 3D food prints. Our study aims to explore the 3D food printability of design features, such as overhangs and holes, and assess how well they print through quantitative and qualitative measurements. Designs with varied angles and diameters based on the standard design limitations for additive manufacturing were printed and measured using marzipan and chocolate. It was found that marzipan material has a minimum feature size for overhang design at 55° and for hole design at 4mm, while chocolate material has a minimum overhang angle size of 35° and does not reliably print holes. Users were presented a series of designs to determine user preference (N = 30) towards the importance of fidelity and accuracy between the expected design and the 3D printed sample, and how much they liked each sample. Results suggest that users prefer designs with high fidelity to their original shape and perceive the current accuracy/precision of 3D printers sufficient for accurately printing three-dimensional geometries. These results demonstrate the current manufacturing capabilities for 3D food printing and success in achieving high fidelity designs for user satisfaction. Both of these considerations are essential steps in providing automated and personalized manufacturing for specific user needs and preferences.

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Impact of Endodontic Instrumentation on Surface Roughness of Various Nickel-Titanium Rotary Files

European Journal of Dentistry ◽

10.1055/s-0040-1718469 ◽

2020 ◽

Cited By ~ 1

Author(s):

Muhammad Sohail Zafar

Keyword(s):

Surface Roughness ◽

Three Dimensional ◽

Nickel Titanium ◽

Root Mean Square Roughness ◽

Contact Mode ◽

Root Canals ◽

Working Length ◽

Mandibular Molar ◽

Significant Difference ◽

Before And After

Abstract Objectives The aim of the present study was to evaluate the surface roughness (SR) of various nickel-titanium (NiTi) rotary endodontic instruments (ProTaper Next [PTN], WaveOne Gold [WOG], and ProTaper Gold [PTG]) before and after root canal instrumentation. Materials and Methods For each type (PTN, WOG, and PTG), the endodontic instrumentation was performed using extracted mandibular molar teeth’s curved mesial root canals (curvature: 20–40 degrees) after determining the working length. Each NiTi file was cleaned, and sterilized following preparation of four root canals and characterized for surface properties before and after endodontic instrumentation using a contact-mode three-dimensional surface profiler. The data were analyzed statistically using Statistical Package for the Social Sciences for SR parameters including average surface roughness value (Sa), root mean square roughness (Sq), and peak to valley height (Sz). Results Preinstrumentation assessment revealed a significant difference for all the three SR variables (p < 0.05) for the cutting blade and the flute area. WOG instruments showed the highest SR values (p = 0.000). The postinstrumentation assessment revealed significant differences in SR values in the blade and the flute between the three groups (p < 0.05), with WOG and PTG exhibiting the highest values in the blade and flute sections, respectively. Conclusions The SR parameters of intact PTN, WOG, and PTG NiTi files vary and that was increased following the endodontic instrumentation.

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Biomechanical Evaluation and Strength Test of 3D-Printed Foot Orthoses

Applied Bionics and Biomechanics ◽

10.1155/2019/4989534 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Kuang-Wei Lin ◽

Chia-Jung Hu ◽

Wen-Wen Yang ◽

Li-Wei Chou ◽

Shun-Hwa Wei ◽

...

Keyword(s):

Mechanical Properties ◽

Motion Capture ◽

Reaction Force ◽

Three Dimensional ◽

Compressive Load ◽

Foot Orthoses ◽

Significant Difference ◽

Optical Motion ◽

3D Printed ◽

Optical Motion Capture

Foot orthoses (FOs) are commonly used as interventions for individuals with flatfoot. Advances in technologies such as three-dimensional (3D) scanning and 3D printing have facilitated the fabrication of custom FOs. However, few studies have been conducted on the mechanical properties and biomechanical effects of 3D-printed FOs. The purposes of this study were to evaluate the mechanical properties of 3D-printed FOs and determine their biomechanical effects in individuals with flexible flatfoot. During mechanical testing, a total of 18 FO samples with three orientations (0°, 45°, and 90°) were fabricated and tested. The maximum compressive load and stiffness were calculated. During a motion capture experiment, 12 individuals with flatfoot were enrolled, and the 3D-printed FOs were used as interventions. Kinematic and kinetic data were collected during walking by using an optical motion capture system. A one-way analysis of variance was performed to compare the mechanical parameters among the three build orientations. A paired t-test was conducted to compare the biomechanical variables under two conditions: walking in standard shoes (Shoe) and walking in shoes embedded with FOs (Shoe+FO). The results indicated that the 45° build orientation produced the strongest FOs. In addition, the maximum ankle evertor and external rotator moments under the Shoe+FO condition were significantly reduced by 35% and 16%, respectively, but the maximum ankle plantar flexor moments increased by 3%, compared with the Shoe condition. No significant difference in ground reaction force was observed between the two conditions. This study demonstrated that 3D-printed FOs could alter the ankle joint moments during gait.

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Three-dimensional printed polylactic acid scaffold integrated with BMP-2 laden hydrogel for precise bone regeneration

Biomaterials Research ◽

10.1186/s40824-021-00233-7 ◽

2021 ◽

Vol 25 (1) ◽

Author(s):

Misun Cha ◽

Yuan-Zhe Jin ◽

Jin Wook Park ◽

Kyung Mee Lee ◽

Shi Huan Han ◽

...

Keyword(s):

Bone Regeneration ◽

Polylactic Acid ◽

Three Dimensional ◽

Burst Release ◽

Defect Model ◽

Ectopic Ossification ◽

Significant Difference ◽

3D Printed

Abstract Background Critical bone defects remain challenges for clinicians, which cannot heal spontaneously and require medical intervention. Following the development of three-dimensional (3D) printing technology is widely used in bone tissue engineering for its outstanding customizability. The 3D printed scaffolds were usually accompanied with growth factors, such as bone morphometric protein 2 (BMP-2), whose effects have been widely investigated on bone regeneration. We previously fabricated and investigated the effect of a polylactic acid (PLA) cage/Biogel scaffold as a carrier of BMP-2. In this study, we furtherly investigated the effect of another shape of PLA cage/Biogel scaffold as a carrier of BMP-2 in a rat calvaria defect model and an ectopic ossification (EO) model. Method The PLA scaffold was printed with a basic commercial 3D printer, and the PLA scaffold was combined with gelatin and alginate-based Biogel and BMP-2 to induce bone regeneration. The experimental groups were divided into PLA scaffold, PLA scaffold with Biogel, PLA scaffold filled with BMP-2, and PLA scaffold with Biogel and BMP-2 and were tested both in vitro and in vivo. One-way ANOVA with Bonferroni post-hoc analysis was used to determine whether statistically significant difference exists between groups. Result The in vitro results showed the cage/Biogel scaffold released BMP-2 with an initial burst release and followed by a sustained slow-release pattern. The released BMP-2 maintained its osteoinductivity for at least 14 days. The in vivo results showed the cage/Biogel/BMP-2 group had the highest bone regeneration in the rat calvarial defect model and EO model. Especially, the bone regenerated more regularly in the EO model at the implanted sites, which indicated the cage/Biogel had an outstanding ability to control the shape of regenerated bone. Conclusion In conclusion, the 3D printed PLA cage/Biogel scaffold system was proved to be a proper carrier for BMP-2 that induced significant bone regeneration and induced bone formation following the designed shape.

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Comparison of 3D-Printed Dental Implants with Threaded Implants for Osseointegration: An Experimental Pilot Study

Materials ◽

10.3390/ma13214815 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4815

Author(s):

Ling Li ◽

Jungwon Lee ◽

Heithem Ben Amara ◽

Jun-Beom Lee ◽

Ki-Sun Lee ◽

...

Keyword(s):

Dental Implants ◽

Three Dimensional ◽

Primary Stability ◽

Titanium Implants ◽

Implant Stability ◽

Implant Surgery ◽

Post Surgery ◽

Significant Difference ◽

3D Printed ◽

Stability Measurements

This study aimed to compare bone healing and implant stability for three types of dental implants: a threaded implant, a three-dimensional (3D)-printed implant without spikes, and a 3D-printed implant with spikes. In four beagle dogs, left and right mandibular premolars (2nd, 3rd, and 4th) and 1st molars were removed. Twelve weeks later, three types of titanium implants (threaded implant, 3D-printed implant without spikes, and 3D-printed implant with spikes) were randomly inserted into the edentulous ridges of each dog. Implant stability measurements and radiographic recordings were taken every two weeks following implant placement. Twelve weeks after implant surgery, the dogs were sacrificed and bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) were compared between groups. At implant surgery, the primary stability was lower for the 3D-printed implant with spikes (74.05 ± 5.61) than for the threaded implant (83.71 ± 2.90) (p = 0.005). Afterwards, no significant difference in implants’ stability was observed between groups up to post-surgery week 12. Histomorphometrical analysis did not reveal a significant difference between the three implants for BIC (p = 0.101) or BAFO (p = 0.288). Within the limits of this study, 3D-printed implants without spikes and threaded implants showed comparable implant stability measurements, BIC, and BAFO.

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