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Journal of Applied Clinical Medical... Nov 2023Avoiding the underlying healthy tissue over-exposure during breast intraoperative electron radiotherapy (IOERT) is owing to the use of some dedicated radioprotection...
BACKGROUND AND OBJECTIVE
Avoiding the underlying healthy tissue over-exposure during breast intraoperative electron radiotherapy (IOERT) is owing to the use of some dedicated radioprotection disks during patient irradiation. The originated contaminant photons from some widely used double-layered shielding disks including PMMA+Cu, PTFE+steel, and Al+Pb configurations during the breast IOERT have been evaluated through a Monte Carlo (MC) simulation approach.
METHODS
Produced electron beam with energies of 6, 8, 10, and 12 MeV by a validated MC model of Liac12 dedicated IOERT accelerator was used for disk irradiations. Each of above-mentioned radioprotection disks was simulated inside a water phantom, so that the upper disk surface was positioned at R depth of each considered electron energy. Simulations were performed by MCNPX (version 2.6.0) MC code. Then, the energy spectra of the contaminant photons at different disk surfaces (upper, middle, and lower one) and relevant contaminant dose beneath the studied disks were determined and compared.
RESULTS
None of studied shielding disks show significant photon contamination up to 10 MeV electron energy, so that the induced photon dose by the contaminant X-rays was lower than those observed in the disk absence under the same conditions. In return, the induced photon dose at a close distance to the lower disk surface exceeded from calculated values in the disk absence at 12 MeV electron energy. The best performance in contaminant dose reduction at the energy range of 6-10 MeV belonged to the Al+Pb disk, while the PMMA+Cu configuration showed the best performance in this regard at 12 MeV energy.
CONCLUSION
Finally, it can be concluded that all studied shielding disks not only don't produce considerable photon contamination but also absorb the originated X-rays from electron interactions with water at the electron energy range of 6-10 MeV. The only concern is related to 12 MeV energy where the induced photon dose exceeds the dose values in the disk absence. Nevertheless, the administered dose by contaminant photons to underlying healthy tissues remains beneath the tolerance dose level by these organs at the entire range of studied electron energies.
Topics: Humans; Electrons; Monte Carlo Method; Lead; Polymethyl Methacrylate; Photons; Water; Radiometry; Radiotherapy Dosage
PubMed: 37461859
DOI: 10.1002/acm2.14098 -
Scientific Reports Jan 2024Microvascular surgery, plastic and reconstructive hand surgery, and coronary artery bypass surgery call for a microanatomical study of the branching pattern of the...
Microvascular surgery, plastic and reconstructive hand surgery, and coronary artery bypass surgery call for a microanatomical study of the branching pattern of the superficial palmar arch (SPA). For the anatomical analysis, we used a group of 20 dissected human hands injected with 4% formaldehyde solution and a 10% mixture of melted gelatin and India ink. The morphometric study was performed on 40 human hands of adult persons injected with methyl-methacrylate fluid into the ulnar and radial arteries simultaneously and afterwards corroded in 40% KOH solution for the preparation of corrosion cast specimens. The mean diameter of the SPA, between the second and third common palmar digital arteries, was 1.86 ± 0.08 mm. We identified the persistent median artery (PMA) in 5% of hands. We distinguished the three main groups of the SPAs according to variations in morphology and branching of the arch: Type 1, the long SPA; Type 2, the middle length SPA; and Type 3, the short SPA found in 27.5% of specimens. The communicating branch (CB), a vessel interconnecting the SPA to the closest branch of the radial artery, is classified into two different morphological groups. The third type of incomplete short arterial arch is the most important of the three groups of SPAs. That short SPA is potentially inadequate for restoring circulation after occlusion or radial artery harvesting for coronary artery bypass.
Topics: Adult; Humans; Cadaver; Hand; Ulnar Artery; Radial Artery; Coronary Artery Bypass
PubMed: 38167619
DOI: 10.1038/s41598-023-50935-2 -
BMC Oral Health Dec 2023This study aims to assess the influence of using 3D-printed acrylic resin versus conventional Poly-methyl methacrylate (PMMA) for fabricating ocular prostheses on the... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
This study aims to assess the influence of using 3D-printed acrylic resin versus conventional Poly-methyl methacrylate (PMMA) for fabricating ocular prostheses on the biofilm and microbial flora of anophthalmic socket.
METHODS
A randomized controlled trial was designed as a parallel group study. Participants were allocated randomly into two groups: the control group, which received conventionally fabricated ocular prostheses (CG, n = 11), and the test group, which received digitally 3D-printed ocular prostheses (DG, n = 11). Microbiological analysis was conducted before prosthesis insertion and three months after using the ocular prosthesis. Swab samples were inoculated on blood agar, MacConkey's agar, and Sabouraud's dextrose agar (SDA) for isolating Gram-positive, Gram-negative, and fungal organisms, respectively. Subsequently, the plates were incubated at 37 degrees Celsius for 48 h. Additionally, a validated questionnaire was used for subjective clinical evaluation, including parameters such as comfort level, socket discharge, lacrimation, and frequency of lubrication for each ocular prosthesis patient in both groups.
RESULTS
Test group (DG, n = 11) exhibited a positive, though statistically insignificant, difference (p > 0.001) in microbial growth when compared to the control group (CG, n = 11). A statistically significant difference was observed in comfort levels between the two groups, with more comfort level within group II (test group) patients. While parameters such as discharge amount, discharge location, lacrimation and lubrication frequency displayed statistically insignificant differences between the two groups, all parameters showed improved results after three months of prosthesis use.
CONCLUSIONS
The choice of ocular prosthesis fabrication technique did not yield a statistically significant difference in anophthalmic flora. However, the 3D-printed acrylic resin, as an artificial eye material, displayed potential advantages in reducing the colonization of opportunistic pathogens. All subjective clinical evaluation parameters exhibited enhanced outcomes after three months of prosthesis use, emphasizing the need for an adaptation period during which patients complains are alleviated. In comparison with PMMA, 3D-printed acrylic resin showcased a certain degree of anti-colonization ability against pathogenic bacteria, along with a significant level of patient comfort, suggesting its potential as a promising material for ocular prostheses.
TRIAL REGISTRATION
This parallel double-blinded RCT has been registered at ClinicalTrials.gov with identification number: NCT05584865, 18/10/2022.
Topics: Humans; Eye, Artificial; Polymethyl Methacrylate; Agar; Anophthalmos; Acrylic Resins; Printing, Three-Dimensional
PubMed: 38110937
DOI: 10.1186/s12903-023-03746-w -
Nihon Hoshasen Gijutsu Gakkai Zasshi Nov 2023The local dense area (LDA) test is a test for evaluating the stability of image quality published in the EUREF fourth edition-supplements for local high-density areas....
The local dense area (LDA) test is a test for evaluating the stability of image quality published in the EUREF fourth edition-supplements for local high-density areas. In this test, a small PMMA plate imitating LDA is placed on a rectangular PMMA, and the exposure conditions and SNR are evaluated when the thickness is changed. In this study, we replaced the rectangular PMMA with a D-shaped PMMA phantom-like breast. Then, we inserted an implant and a muscle phantom simulating the pectoral muscle and varied the distance from the edge of the chest wall to a small PMMA plate. In most of the tests, the SNR was stable as the thickness of the small PMMA plate increased as the exposure conditions increased. However, the SNR was not stable because the exposure conditions were not appropriate depending on the insertion distance of the muscle phantom and the position of the small PMMA plate.
Topics: Polymethyl Methacrylate; Radiation Dosage; Mammography; Thorax; Phantoms, Imaging; Radiographic Image Enhancement
PubMed: 37793833
DOI: 10.6009/jjrt.2023-1388 -
Effects of hexagonal boron nitride on mechanical properties of bone cement (Polymethylmethacrylate).Joint Diseases and Related Surgery Feb 2024The aim of this study was to investigate the effects of adding hexagonal boron nitride at four different concentrations to polymethylmethacrylate (PMMA) bone cement,...
OBJECTIVES
The aim of this study was to investigate the effects of adding hexagonal boron nitride at four different concentrations to polymethylmethacrylate (PMMA) bone cement, which is commonly used in orthopedic surgeries, on the mechanical properties and microarchitecture of the bone cement.
MATERIALS AND METHODS
The study included an unaltered control group and groups containing four different concentrations (40 g of bone cement with 0.5 g, 1 g, 1.5 g, 2 g) of hexagonal boron nitride. The samples used for mechanical tests were prepared at 20±2ºC in operating room conditions, using molds in accordance with the test standards. As a result of the tests, the pressure values at which the samples deformed were determined from the load-deformation graphs, and the megapascal (MPa) values at which the samples exhibited strength were calculated.
RESULTS
The samples with 0.5 g boron added to the bone cement had significantly increased mechanical strength, particularly in the compression test. In the group where 2 g boron was added, it was noted that, compared to the other groups, the strength pressure decreased and the porosity increased. The porosity did not change particularly in the group where 0.5 g boron was added.
CONCLUSION
Our study results demonstrate that adding hexagonal boron nitride (HBN) to bone cement at a low concentration (0.5 g / 40 g PPMA) significantly increases the mechanical strength in terms of MPa (compression forces) without adversely affecting porosity. However, the incorporation of HBN at higher concentrations increases porosity, thereby compromising the biomechanical properties of the bone cement, as evidenced by the negative impact on compression and four-point bending tests. Boron-based products have gained increased utilization in the medical field, and HBN is emerging as a promising chemical compound, steadily growing in significance.
Topics: Boron Compounds; Polymethyl Methacrylate; Bone Cements; Materials Testing; Porosity; Compressive Strength; Stress, Mechanical
PubMed: 38727113
DOI: 10.52312/jdrs.2024.1513 -
ACS Sensors May 2024In this study, we demonstrate whole blood immunoassays using a microfluidic device optimized for conducting rapid and multiplexed fluorescence-linked immunoassays. The...
In this study, we demonstrate whole blood immunoassays using a microfluidic device optimized for conducting rapid and multiplexed fluorescence-linked immunoassays. The device is capable of handling whole blood samples without any preparatory treatment. The three-dimensional channels in poly(methyl methacrylate) are designed to passively load bodily fluids and, due to their linearly tapered profile, facilitate size-dependent immobilization of biofunctionalized particles. The channel geometry is optimized to allow for the unimpeded flow of cellular constituents such as red blood cells (RBCs). Additionally, to make the device easier to operate, the biofunctionalized particles are pretrapped in a first step, and the channel is dried under vacuum, after which it can be loaded with the biological sample. This novel approach and design eliminated the need for traditionally laborious steps such as filtering, incubation, and washing steps, thereby substantially simplifying the immunoassay procedures. Moreover, by leveraging the shallow device dimensions, we show that sample loading to read-out is possible within 5 min. Our results also show that the presence of RBCs does not compromise the sensitivity of the assays when compared to those performed in a pure buffer solution. This highlights the practical adaptability of the device for simple and rapid whole-blood assays. Lastly, we demonstrate the device's multiplexing capability by pretrapping particles of different sizes, each functionalized with a different antigen, thus enabling the performance of multiplexed on-chip whole-blood immunoassays, showcasing the device's versatility and effectiveness toward low-cost, simple, and multiplexed sensing of biomarkers and pathogens directly in whole blood.
Topics: Humans; Immunoassay; Microfluidic Analytical Techniques; Erythrocytes; Lab-On-A-Chip Devices; Polymethyl Methacrylate
PubMed: 38687557
DOI: 10.1021/acssensors.4c00153 -
PloS One 2024Silk fibroin nanoparticles (FNP) have been increasingly investigated in biomedical fields due to their biocompatibility and biodegradability properties. To widen the FNP...
Silk fibroin nanoparticles (FNP) have been increasingly investigated in biomedical fields due to their biocompatibility and biodegradability properties. To widen the FNP versatility and applications, and to control the drug release from the FNP, this study developed the Eudragit S100-functionalized FNP (ES100-FNP) as a pH-responsive drug delivery system, by two distinct methods of co-condensation and adsorption, employing the zwitterionic furosemide as a model drug. The particles were characterized by sizes and zeta potentials (DLS method), morphology (electron microscopy), drug entrapment efficiency and release profiles (UV-Vis spectroscopy), and chemical structures (FT-IR, XRD, and DSC). The ES100-FNP possessed nano-sizes of ∼200-350 nm, zeta potentials of ∼ -20 mV, silk-II structures, enhanced thermo-stability, non-cytotoxic to the erythrocytes, and drug entrapment efficiencies of 30%-60%, dependent on the formulation processes. Interestingly, the co-condensation method yielded the smooth spherical particles, whereas the adsorption method resulted in durian-shaped ones due to furosemide re-crystallization. The ES100-FNP adsorbed furosemide via physical adsorption, followed Langmuir model and pseudo-second-order kinetics. In the simulated oral condition, the particles could protect the drug in the stomach (pH 1.2), and gradually released the drug in the intestine (pH 6.8). Remarkably, in different pH conditions of 6.8, 9.5, and 12, the ES100-FNP could control the furosemide release rates depending on the formulation methods. The ES100-FNP made by the co-condensation method was mainly controlled by the swelling and corrosion process of ES100, and followed the Korsmeyer-Peppas non-Fickian transport mechanism. Whereas, the ES100-FNP made by the adsorption method showed constant release rates, followed the zero-order kinetics, due to the gradual furosemide dissolution in the media. Conclusively, the ES100-FNP demonstrated high versatility as a pH-responsive drug delivery system for biomedical applications.
Topics: Fibroins; Hydrogen-Ion Concentration; Nanoparticles; Furosemide; Drug Delivery Systems; Polymethacrylic Acids; Drug Liberation; Drug Carriers; Particle Size; Animals; Humans; Spectroscopy, Fourier Transform Infrared
PubMed: 38781182
DOI: 10.1371/journal.pone.0303177 -
Clinical and Experimental Dental... Jun 2024To study the feasibility of using poly methyl methacrylate (PMMA) filament and fused deposition modeling (FDM) to manufacture denture bases via the development of a...
OBJECTIVE
To study the feasibility of using poly methyl methacrylate (PMMA) filament and fused deposition modeling (FDM) to manufacture denture bases via the development of a study that considers both conventional and additive-based manufacturing techniques.
MATERIALS AND METHODS
Five sample groups were compared: heat and cold cured acrylic resins, CAD/CAM milled PMMA, 3D-printed PMMA (via FDM), and 3D-printed methacrylate resin (via stereolithography, SLA). All groups were subjected to mechanical testing (flexural strength, impact strength, and hardness), water sorption and solubility tests, a tooth bonding test, microbiological assessment, and accuracy of fit measurements. The performance of sample groups was referred to ISO 20795-1 and ISO/TS 19736. The data was analyzed using one-way ANOVA.
RESULTS
Samples manufactured using FDM performed within ISO specifications for mechanical testing, water sorption, and solubility tests. However, the FDM group failed to achieve the ISO requirements for the tooth bonding test. FDM samples presented a rough surface finish which could ultimately encourage an undesirable high level of microbial adhesion. For accuracy of fit, FDM samples showed a lower degree of accuracy than existing materials.
CONCLUSIONS
Although FDM samples were a cost-effective option and were able to be quickly manufactured in a reproducible manner, the results demonstrated that current recommended testing regimes for conventionally manufactured denture-based polymers are not directly applicable to additive-manufactured denture base polymers. Therefore, new standards should be developed to ensure the correct implementation of additive manufacturing techniques within denture-based fabrication workflow.
Topics: Denture Bases; Polymethyl Methacrylate; Printing, Three-Dimensional; Computer-Aided Design; Materials Testing; Acrylic Resins; Denture Design; Humans; Feasibility Studies; Dental Materials; Dental Bonding; Surface Properties; Stereolithography; Flexural Strength; Hardness; Solubility
PubMed: 38798134
DOI: 10.1002/cre2.880 -
Acta Cirurgica Brasileira 2023This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs.
PURPOSE
This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs.
METHODS
In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate-PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure.
RESULTS
All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups.
CONCLUSIONS
The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.
Topics: Animals; Dogs; Atlanto-Axial Joint; Polymethyl Methacrylate; Bone Cements; Tomography, X-Ray Computed
PubMed: 37729349
DOI: 10.1590/acb383223 -
The Journal of Prosthetic Dentistry May 2024Three-dimensionally (3D)-printed composite resins have been marketed as materials for definitive restorations. However, limited information is available regarding the... (Comparative Study)
Comparative Study
STATEMENT OF PROBLEM
Three-dimensionally (3D)-printed composite resins have been marketed as materials for definitive restorations. However, limited information is available regarding the stability of the adhesive interface and the efficiency of 3D printed composite resins.
PURPOSE
The purpose of this in vitro study was to evaluate the integrity of the marginal adhesive interface before and after thermal and mechanical fatigue of an initial formulation of a 3D printed composite resin and to evaluate the efficiency of this manufacturing method.
MATERIAL AND METHODS
Freshly extracted molars were prepared for onlays and adhesively restored with either 3D printed composite resin (VarseoSmile Crown Plus) (Group 3D), milled composite resin (Tetric CAD) (Group MCOMP), milled PMMA (Telio CAD) (Group PMMA), and milled lithium disilicate (IPS e.max CAD) (Group EM). Marginal analysis was performed under a scanning electron microscope before and after fatigue by thermomechanical cyclic loading, and initial and terminal percentages of continuous margin (%CM) were compared. The time required for the production of each type of restoration was recorded, and the production costs were also compared.
RESULTS
Before aging, 3D, MCOMP, and EM presented comparable values of %CM (69.8%, 75.9%, and 63.1%, respectively) that were statistically significantly higher (P<.05) than those of PMMA (45.1%). After aging, 3D and EM had comparable results (44.7% and 43.7%, respectively), which were lower than those of the MCOMP group (68.5%) but higher than those of the PMMA group (20.5%). Regarding time efficiency, 3D printing took less time than MCOMP or PMMA if more than 8 restorations were fabricated. For the production costs, 3D printing was 5.5, 8.7, and 10.2 times less expensive than PMMA, MCOMP, and EM, respectively. The initial equipment cost was also lower for the additive manufacturing method. However, 3D printing did not always considerably reduce waste.
CONCLUSIONS
In terms of marginal adaptation, the evaluated initial formulation of a 3D printed composite resin behaved similarly to other well-established definitive restoration materials and better than milled PMMA, both before and after fatigue. Three-dimensionally printed resins present advantages in terms of equipment and consumable costs, even for a single restoration, but also for production time when more than 8 restorations were fabricated.
Topics: Composite Resins; Printing, Three-Dimensional; Humans; In Vitro Techniques; Materials Testing; Dental Restoration, Permanent; Dental Materials; Polymethyl Methacrylate; Time Factors; Molar; Dental Stress Analysis
PubMed: 36333176
DOI: 10.1016/j.prosdent.2022.08.001