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The Journal of Prosthetic Dentistry Nov 2023Structured-light and computed tomography industrial scanners have been used as reference scanners to measure marginal gaps between implants and superstructures. However,...
STATEMENT OF PROBLEM
Structured-light and computed tomography industrial scanners have been used as reference scanners to measure marginal gaps between implants and superstructures. However, the effect of framework material on the scanners' ability to detect gaps and on precision has not yet been evaluated.
PURPOSE
The purpose of this in vitro study was to investigate the interaction between the industrial scanner and framework material on measured marginal gaps of implant-supported fixed complete arch frameworks made from titanium and polymethylmethacrylate and on the precision of scans.
MATERIAL AND METHODS
A completely edentulous maxillary model with 4 implants and multiunit abutments at the first molar and canine sites was digitized by using a laboratory scanner. Implant-supported frameworks were milled from titanium and polymethylmethacrylate (n=5). Each framework was secured on the left molar site abutment. The marginal gaps between the frameworks and abutment sites without a screw were measured by using an industrial structured-light scanner and an industrial computed tomography scanner. The effect of the scanner, the framework material, and their interaction on measured gaps was analyzed by applying linear regressions and weighted least square methods. The F-statistics was used with Bonferroni corrections for precision analysis (α=.05).
RESULTS
No significant effect of scanner, material, or their interaction was found on the marginal gaps at the canine sites. The titanium framework gaps detected by using the computed tomography scanner were greater than those detected by using the structured-light scanner at the right molar site (estimated difference in means=0.054 mm; P=.003) and overall (estimated difference in means=0.023 mm; P=.033). The structured-light scanner's precision was higher than that of the computed tomography scanner when titanium frameworks were scanned (P=.001). The computed tomography scanner's precision was higher when scanning polymethylmethacrylate frameworks than when scanning titanium frameworks (P=.03).
CONCLUSIONS
Framework material and industrial scanner interaction affected the measured gaps. The computed tomography scanner detected greater marginal gaps with low precision when scanning titanium frameworks than the structured-light scanner. The sample size, the use of only 2 types of materials, and a laboratory scanner to obtain the computer-aided design file should be considered when interpreting the results.
Topics: Polymethyl Methacrylate; Titanium; Dental Implants; Tomography Scanners, X-Ray Computed; Computer-Aided Design; Dental Prosthesis, Implant-Supported
PubMed: 34998580
DOI: 10.1016/j.prosdent.2021.10.013 -
Environmental Research Jul 2023The identification of health risks arising from occupational exposure to submicron/nanoscale materials is of particular interest and toxicological investigations...
The identification of health risks arising from occupational exposure to submicron/nanoscale materials is of particular interest and toxicological investigations designed to assess their hazardous properties can provide valuable insights. The core-shell polymers poly (methyl methacrylate)@poly (methacrylic acid-co-ethylene glycol dimethacrylate) [PMMA@P (MAA-co-EGDMA)] and poly (n-butyl methacrylate-co-ethylene glycol dimethacrylate)@poly (methyl methacrylate) [P (nBMA-co-EGDMA)@PMMA] could be utilized for the debonding of coatings and for the encapsulation and targeted delivery of various compounds. The hybrid superabsorbent core-shell polymers poly (methacrylic acid-co-ethylene glycol dimethacrylate)@silicon dioxide [P (MAA-co-EGDMA)@SiO] could be utilized as internal curing agents in cementitious materials. Therefore, the characterization of their toxicological profile is essential to ensure their safety throughout manufacturing and the life cycle of the final products. Based on the above, the purpose of the present study was to assess the acute toxic effects of the above mentioned polymers on cell viability and on cellular redox state in EA. hy926 human endothelial cells and in RAW264.7 mouse macrophages. According to our results, the examined polymers did not cause any acute toxic effects on cell viability after any administration. However, the thorough evaluation of a panel of redox biomarkers revealed that they affected cellular redox state in a cell-specific manner. As regards EA. hy926 cells, the polymers disrupted redox homeostasis and promoted protein carbonylation. Concerning RAW264.7 cells, P (nBMA-co-EGDMA)@PMMA caused disturbances in redox equilibrium and special emphasis was placed on the triphasic dose-response effect detected in lipid peroxidation. Finally, P (MAA-co-EGDMA)@SiO activated cellular adaptive mechanisms in order to prevent from oxidative damage.
Topics: Animals; Mice; Humans; Polymers; Polymethyl Methacrylate; Silicon Dioxide; Endothelial Cells; Methacrylates
PubMed: 36967000
DOI: 10.1016/j.envres.2023.115772 -
The International Journal of... Nov 2023To assess if the implant-retained prostheses produced with laser-sintering technique present an accuracy and passive fit comparable to their milled counterpart.
PURPOSE
To assess if the implant-retained prostheses produced with laser-sintering technique present an accuracy and passive fit comparable to their milled counterpart.
MATERIALS AND METHODS
Two regular neck Straumann analogs were placed in a block of PMMA 15 mm apart and parallel to each other. The PMMA block was then scanned and two groups of cobalt-chromium, screw-retained, three-unit implant prostheses were fabricated using milling (control) and laser-sintering (test) techniques. The prostheses were then screwed on the PMMA block and the vertical marginal gap between the prostheses and the analogs at the implant-abutment junction was measured twice, (1) when only one screw was tightened, and (2) when both screws were fully tightened. The average of each marginal gap measurement was compared to assess the difference in term of passive fit between the laser-sintered and the milled prostheses.
RESULTS
The mean marginal gap of the milled and the laser-sintered groups were 23.18 µm (SD = 6.2) and 23.71 µm (SD = 19.5) respectively.
CONCLUSIONS
Laser-sintered prostheses presented a marginal fit comparable to their milled counterpart and represent a clinically valid alternative to their milled counterpart. Int J Prosthodont 2023;36:e53-e60.
Topics: Dental Implants; Polymethyl Methacrylate; Dental Marginal Adaptation; Computer-Aided Design; Dental Prosthesis, Implant-Supported; Lasers
PubMed: 33662050
DOI: 10.11607/ijp.7261 -
European Journal of Medical Research Jun 2023Sepsis occurs as a result of dysregulated host response to infection. However, cytokine adsorption therapy may restore the balance of proinflammatory and... (Randomized Controlled Trial)
Randomized Controlled Trial
Comparison of the cytokine adsorption ability in continuous renal replacement therapy using polyethyleneimine-coated polyacrylonitrile (AN69ST) or polymethylmethacrylate (PMMA) hemofilters: a pilot single-center open-label randomized control trial.
BACKGROUND
Sepsis occurs as a result of dysregulated host response to infection. However, cytokine adsorption therapy may restore the balance of proinflammatory and anti-inflammatory mediator responses in patients with sepsis. This study aimed to determine the cytokine adsorption ability of two different types of continuous renal replacement therapy (CRRT) hemofilters for polyethyleneimine-coated polyacrylonitrile (AN69ST) (surface-treated) and polymethylmethacrylate (PMMA) CRRT.
METHODS
We performed a randomized controlled trial among sepsis patients undergoing CRRT, who were randomly assigned (1:1) to receive either AN69ST or PMMA-CRRT. The primary outcome was cytokine clearance of hemofilter adsorption (CHA). The secondary endpoints were the intensive care unit (ICU) and 28-day mortalities.
RESULTS
We randomly selected 52 patients. Primary outcome data were available for 26 patients each in the AN69ST-CRRT and PMMA-CRRT arms. The CHA of high-mobility group box 1, tumor necrosis factor, interleukin (IL)-8, monokine induced by interferon-γ, and macrophage inflammatory protein were significantly higher in the AN69ST-CRRT group than in the PMMA-CRRT group (P < 0.001, P < 0.01, P < 0.001, P < 0.001 and P < 0.001, respectively). In contrast, the CHA of IL-6 was significantly higher in the PMMA-CRRT group than in the AN69ST-CRRT group (P < 0.001). In addition, the 28-day mortality was not significantly different between the two groups (50% in AN69ST-CRRT vs. 30.8% in PMMA-CRRT, P = 0.26).
CONCLUSION
AN69ST and PMMA membranes have different cytokine CHA in patients with sepsis. Therefore, these two hemofilters may have to be used depending on the target cytokine.
TRIAL REGISTRATION NUMBER
This study was registered in the University Hospital Medical Information Network on November 1, 2017 (Trial No: UMIN000029450, https://center6.umin.ac.jp ).
Topics: Humans; Continuous Renal Replacement Therapy; Cytokines; Polymethyl Methacrylate; Polyethyleneimine; Adsorption
PubMed: 37391846
DOI: 10.1186/s40001-023-01184-6 -
Dental Materials : Official Publication... Sep 2023to characterize the effects of graphene oxide (GO) on polymethyl methacrylate's (PMMA) reliability and lifetime. The hypothesis tested was that GO would increase both...
OBJECTIVES
to characterize the effects of graphene oxide (GO) on polymethyl methacrylate's (PMMA) reliability and lifetime. The hypothesis tested was that GO would increase both Weibull parameters and decreased strength degradation over time.
METHODS
PMMA disks containing GO (0.01, 0.05, 0.1, or 0.5 wt%) were subjected to a biaxial flexural test to determine the Weibull parameters (m: modulus of Weibull; σ0: characteristic strength; n = 30 at 1 MPa/s) and slow crack growth (SCG) parameters (n: subcritical crack growth susceptibility coefficient, σf0: scaling parameter; n = 10 at 10-2, 10-1, 101, 100 and 102 MPa/s). Strength-probability-time (SPT) diagrams were plotted by merging SCG and Weibull parameters.
RESULTS
There was no significant difference in the m value of all materials. However, 0.5 GO presented the lowest σ0, whereas all other groups were similar. The lowest n value obtained for all GO-modified PMMA groups (27.4 for 0.05 GO) was higher than the Control (15.6). The strength degradation predicted after 15 years for Control was 12%, followed by 0.01 GO (7%), 0.05 GO (9%), 0.1 GO (5%), and 0.5 GO (1%).
SIGNIFICANCE
The hypothesis was partially accepted as GO increased PMMA's fatigue resistance and lifetime but did not significantly improve its Weibull parameters. GO added to PMMA did not significantly affect the initial strength and reliability but significantly increased PMMA's predicted lifetime. All the GO-containing groups presented higher resistance to fracture at all times analyzed compared with the Control, with the best overall results observed for 0.1 GO.
Topics: Polymethyl Methacrylate; Materials Testing; Reproducibility of Results; Graphite; Surface Properties; Ceramics
PubMed: 37400298
DOI: 10.1016/j.dental.2023.06.009 -
The Science of the Total Environment Feb 2024Nanoplastic particles are pervasive environmental contaminants with potential health risks, while mouse intestinal organoids provide accurate in vitro models for...
Nanoplastic particles are pervasive environmental contaminants with potential health risks, while mouse intestinal organoids provide accurate in vitro models for studying these interactions. Metabolomics, especially through LC-MS, enables detailed cellular response studies, and there's a novel interest in comparing metabolic changes across nanoparticle species using gut organoids. This study used a mouse intestinal organoid combined with cell model to explore the differences in metabolites and toxicity mechanisms induced by exposure to three nanoplastics (PS, PTFE, and PMMA). The results showed that PS, PTFE, and PMMA exposure reduced mitochondrial membrane potential, intracellular ROS accumulation and oxidative stress, and inhibited the AKT/mTOR signaling pathway. Non-targeted metabolomics results confirmed that three types of nanoplastic particles regulate cellular status by regulating fatty acid metabolism, nucleotide metabolism, necroptosis and autophagy pathways. More importantly, these representative metabolites were further validated in model groups after mouse intestinal organoids and HCT116 cells were exposed to the respective NPs, indicating that organoid metabolomics results can be used to effectively predict toxicity. Untargeted metabolomics is sensitive enough to detect subtle metabolomic changes when functional cellular analysis shows no significant differences. Overall, our study reveals the underlying metabolic mechanism of NPs-induced intestinal organoid toxicity and provides new insights into the possible adverse consequences of NPs.
Topics: Animals; Mice; Microplastics; Polymethyl Methacrylate; Metabolomics; Nanoparticles; Organoids; Polytetrafluoroethylene; Polystyrenes
PubMed: 38159744
DOI: 10.1016/j.scitotenv.2023.169606 -
International Journal of Molecular... Nov 2023Polymer nanoparticles continue to be of high interest in life science applications. Still, adsorption processes occurring in protein-containing media and their...
Polymer nanoparticles continue to be of high interest in life science applications. Still, adsorption processes occurring in protein-containing media and their implications for biological responses are not generally predictable. Here, the effect of nanoparticle composition on the adsorption of bovine serum albumin (BSA), fibronectin (FN) and immunoglobulin G (IgG) as structurally and functionally different model proteins was explored by systematically altering the composition of poly(methyl methacrylate--styrene) nanoparticles with sizes in a range of about 550 nm. As determined by protein depletion from the suspension medium via a colorimetric assay, BSA and IgG adsorbed at similar quantities, while FN reached larger masses of adsorbed protein (up to 0.4 ± 0.06 µg·cm BSA, 0.42 ± 0.09 µg·cm IgG, 0.72 ± 0.04 µg·cm FN). A higher content of styrene as the more hydrophobic polymer component enhanced protein binding, which suggests a contribution of hydrophobic interactions despite the particles exhibiting strongly negatively charged surfaces with zeta potentials of -44 to -52 mV. The quantities of adsorbed proteins were estimated to correspond to a confluent surface coverage. Overall, this study illustrated how protein binding can be controlled by systematically varying the nanoparticle bulk composition and may serve as a basis for establishing interfaces with a targeted level of protein retention and/or presentation.
Topics: Styrene; Polymethyl Methacrylate; Nanoparticles; Serum Albumin, Bovine; Immunoglobulin G; Methacrylates; Adsorption; Surface Properties
PubMed: 38003579
DOI: 10.3390/ijms242216390 -
Biomedical Microdevices Dec 2023PMMA-based microfluidics have been widely used in various applications in biological and chemical fields. In the fabrication process of PMMA-based microfluidics, the...
PMMA-based microfluidics have been widely used in various applications in biological and chemical fields. In the fabrication process of PMMA-based microfluidics, the substrate and cover plate usually need to be bonded to enclose the microchannel. The bonding process could be permanent or reversible. In some application scenarios, reversible bonding is needed to retrieve the samples inside the channel or reuse the chip. Current reversible bonding methods for PMMA-based microfluidics usually have drawbacks on bonding strength and contaminations from the adhesives used in the bonding process. In this study, a new approach is proposed for the reversible bonding of PMMA-based microfluidics, a layer of PBMA (with a very similar structure to PMMA) was coated on the surface of PMMA and then use the thermal fusion method to achieve the bonding with a high bonding strength, a tensile bonding strength of around 0.8 MPa was achieved. For debond process, a rapid temperature drop will trigger the immediate release of the bonding within several seconds. Detailed bonding strength measurement and biocompatibility tests were also conducted in this study. The proposed bonding method could have wide application potential in the fabrication of PMMA-based microfluidics.
Topics: Polymethyl Methacrylate; Microfluidics; Lab-On-A-Chip Devices; Temperature
PubMed: 38141082
DOI: 10.1007/s10544-023-00690-y -
Journal of Materials Chemistry. B Sep 2023Macrophages are immune cells that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Attempts to modulate macrophage phenotype using...
Macrophages are immune cells that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes. Attempts to modulate macrophage phenotype using drugs have been limited by targeting issues and systemic toxicity. This study investigates the effect of drug-free self-assembled hydrolyzed galactomannan-poly(methyl methacrylate) (hGM--PMMA) nanoparticles on the activation of the human monocyte-derived macrophage THP-1 cell line. Nanoparticles are cell compatible and are taken up by macrophages. RNA-sequencing analysis of cells exposed to NPs reveal the upregulation of seven metallothionein genes. Additionally, the secretion of pro-inflammatory and anti-inflammatory cytokines upon exposure of unpolarized macrophages and M1-like cells obtained by activation with lipopolysaccharide + interferon-γ to the NPs is reduced and increased, respectively. Finally, nanoparticle-treated macrophages promote fibroblast migration . Overall, results demonstrate that hGM--PMMA nanoparticles induce the release of anti-inflammatory cytokines by THP-1 macrophages, which could pave the way for their application in the therapy of different inflammatory conditions, especially by local delivery.
Topics: Humans; Polymethyl Methacrylate; Anti-Inflammatory Agents; Cytokines; Macrophages; Nanoparticles; Phenotype
PubMed: 37587844
DOI: 10.1039/d3tb01397a -
Journal of Cancer Research and Clinical... Aug 2023Vertebroplasty is a minimally invasive outpatient procedure to stabilize compression fractures in the spine. This procedure involves injecting bone cement into the...
BACKGROUND
Vertebroplasty is a minimally invasive outpatient procedure to stabilize compression fractures in the spine. This procedure involves injecting bone cement into the vertebrae that have been cracked or broken, typically due to osteoporosis. The cement hardens inside the bones, providing stability to the fractures and supporting the spine. Additionally, radioactive bone cement and brachytherapy sources have been utilized to suppress tumor growth in the vertebral body.
OBJECTIVE
We present a novel brachytherapy technique for treating vertebral body metastases using a liquid form of radioactive sources, Phosphorus-32 and Lutetium-177, separately mixed with bone cement and injected into vertebral body bone prostheses. We also investigated the dose distribution of the radioactive bone cement by theoretically calculating it using GEANT4 Monte Carlo and measuring it using TLD dosimeters for Phosphorus-32 and Lutetium-177 loaded in vertebral bodies.
MATERIAL AND METHODS
CT-scanned images of each vertebral body (L2 and L3) were imported into GEANT4 for simulation purposes. Two simulations were performed to evaluate the possibility of using PLA prostheses in ex vivo measurements, using bone and PLA material as a bone substitute for brachytherapy of Lutetium-177 and Phosphorus-32. The simulations calculated the dose distribution, dose rates, and deposited dose to the spinal cord and aorta. Next, 3D-printed bone prostheses were drilled and separately filled with bone cement, including PMMA-P32 and PMMA-Lu177, in liquid form using the Vertebroplasty technique. The dose to regions of interest was measured using Thermoluminescence dosimeters.
CONCLUSIONS
When comparing the simulated and measured results of dose rates, it was observed that P32 delivers higher doses to normal organs such as the spinal cord and aorta. At the same time, Lu177 has better sparing in these regions of interest. Therefore, while P32 and Lu177 are suitable for radioactive bone cement treatment, Lu177 delivers relatively lower doses to vital organs such as the spinal cord and aorta. Additionally, Lu177 has characteristics such as a shorter range and lower energies of beta particles in tissue and the presence of gamma rays that make it a better choice for the same treatments. It also provides the possibility of SPECT imaging.
Topics: Humans; Bone Cements; Polymethyl Methacrylate; Vertebral Body; Spinal Fractures; Vertebroplasty; Polyesters; Treatment Outcome
PubMed: 36959343
DOI: 10.1007/s00432-023-04695-1