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Dental Materials Journal Jun 2024This study investigated residual stresses in glass crowns cemented with resin cements. Glass caps were cemented to cylindrical cores using a conventional resin composite...
This study investigated residual stresses in glass crowns cemented with resin cements. Glass caps were cemented to cylindrical cores using a conventional resin composite cement, a self-adhesive resin cement, or a methyl methacrylate (MMA)-based cement in dual-cure or self-cure mode. The cemented caps were stored in 37°C water for 28 days, and stresses on the cap surface were repeatedly measured. The water sorption, water solubility, and elastic modulus of the cements were also measured. Polymerization of the cements initially generated compressive stresses on the surfaces. Dual-curing or a greater modulus yielded greater initial stress. The stresses gradually decreased over time and lingered on the surfaces at 28 days with all the cements. Greater sorption tended to lead to greater stress reduction; however, the MMA-based cement exhibited less stress reduction despite exhibiting the greatest sorption. The use of a resin composite cement or dual-curing is recommended to reinforce crown restorations.
Topics: Resin Cements; Polymerization; Crowns; Water; Materials Testing; Glass; Dental Stress Analysis; Elastic Modulus; Stress, Mechanical; Composite Resins; Surface Properties; Methylmethacrylate; Solubility
PubMed: 38719584
DOI: 10.4012/dmj.2023-283 -
Environmental Pollution (Barking, Essex... Jul 2024Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current...
Microplastics (MPs) are growing and ubiquitous environmental pollutants and represent one of the greatest contemporary challenges caused by human activities. Current research has predominantly examined the singular toxicological effects of individual polymers, neglecting the prevailing reality of organisms confronted with complex contaminant mixtures and potential synergistic effects. To fill this research gap, we investigated the lethal and sublethal effects of two common MPs, polystyrene (PS - 4.8-5.8 μm) and poly(methyl methacrylate) (PMMA - 1-40 μm), and their combination (MIX), on the pollinating insect Apis mellifera. For each treatment, we evaluated the oral toxicity of two ecologically relevant and one higher concentration (0.5, 5 and 50 mg/L) and analysed their effects on the immune system and worker survival. As immune activation can alter the cuticular hydrocarbon profile of honey bees, we used gas chromatography-mass spectrometry (GC-MS) to investigate whether MPs lead to changes in the chemical profile of foragers and behavioural assay to test whether such changes affect behavioural patterns of social recognition, undermining overall colony integrity. The results indicate an additive negative effect of PS and PMMA on bee survival and immune response, even at ecologically relevant concentrations. Furthermore, alterations in cuticle profiles were observed with both MPs at the highest and intermediate concentrations, with PMMA being mainly responsible. Both MPs exposure resulted in a reduction in the abundance of several cuticular compounds. Hive entry guards did not show increased inspection or aggressive behaviour towards exposed foragers, allowing them to enter the colony without being treated differently from uncontaminated foragers. These findings raise concerns not only for the health of individual bees, but also for the entire colony, which could be at risk if contaminated nestmates enter the colony undetected, allowing MPs to spread throughout the hive.
Topics: Bees; Animals; Microplastics; Environmental Pollutants; Polystyrenes; Polymethyl Methacrylate; Polymers
PubMed: 38703977
DOI: 10.1016/j.envpol.2024.124087 -
International Journal of Pharmaceutics Jun 2024The aim of this study was to prepare nintedanib nanocrystals (BIBF-NCs) to lower the solubility of the drug in the stomach, maintain the supersaturation of the drug in...
The aim of this study was to prepare nintedanib nanocrystals (BIBF-NCs) to lower the solubility of the drug in the stomach, maintain the supersaturation of the drug in the intestine, and improve the oral absorption of nintedanib (BIBF). In this study, BIBF-NCs were prepared by acid solubilization and alkaline precipitation following nano granding method, with a particle size of 290.80 nm and a zeta potential of -49.13 mV. Subsequently, Nintedanib enteric-coated nanocrystals (BIBF-NCs@L100) were obtained by coating with Eudragit L100. The microscopic morphology, crystalline characteristics, stability, and in vitro dissolution of BIBF-NCs and BIBF-NCs@L100 were also studied. In addition, the in vivo pharmacokinetic behaviors of Samples prepared according to the prescription process of commercially available soft capsules (soft capsules), BIBF-NCs, and BIBF-NCs@L100 were further investigated. The results showed that the oral bioavailability of BIBF-NCs and BIBF-NCs@L100 were increased by 1.43 and 2.58 times, compared with that of the soft capsules. BIBF-NCs@L100 effectively reduced the release of BIBF in the formulation in the stomach, allowing more drug to reach the intestine in the form of nanocrystals, maintaining the supersaturation in the intestine, thereby improving the oral bioavailability of the drug.
Topics: Nanoparticles; Indoles; Biological Availability; Animals; Administration, Oral; Particle Size; Solubility; Polymethacrylic Acids; Male; Drug Liberation; Rats, Sprague-Dawley
PubMed: 38703933
DOI: 10.1016/j.ijpharm.2024.124196 -
Journal of Dentistry Jul 2024To evaluate the mechanical, wear, antibacterial properties, and biocompatibility of injectable composite materials.
OBJECTIVES
To evaluate the mechanical, wear, antibacterial properties, and biocompatibility of injectable composite materials.
METHODS
Two injectable composite resins (GU and BI), one flowable composite resin (FS), and one flowable compomer (DF), in A2 shade, were tested. Mechanical properties were tested via three-point bending test immediately after preparation and after 1-day, 7-day, 14-day, and 30-day water storage. Under water-PMMA slurry immersion, specimens were subjected to a 3-body wear test (10,000 cycles) against stainless steel balls, while the roughness, wear depth, and volume loss were recorded. After 1-day and 3-day MC3T3-E1 cell culture, cell viability was evaluated with CCK-8 test kits, while the cell morphology was observed under CLSM and SEM. Antibacterial properties on S. mutans were assessed via CFU counting, CLSM, and SEM observation. SPSS 26.0 was used for statistical analysis (α = 0.05).
RESULTS
The mechanical properties were material-dependent and sensitive to water storage. Flexural strength ranked GU > FS > BI > DF at all testing levels. Three nanocomposites had better wear properties than DF. No significant difference on 1-day cell viability was found, but DF showed significantly lower cell proliferation than nanocomposites on 3-day assessment. GU and FS had more favourable cell adhesion and morphology. CFU counting revealed no significant difference, while FS presented a slightly thicker biofilm and BI showed relatively lower bacteria density.
CONCLUSIONS
Injectable nanocomposites outperformed the compomer regarding mechanical properties, wear resistance, and biocompatibility. The tested materials presented comparable antibacterial behaviours. Flowable resin-based composites' performances are affected by multiple factors, and their compositions can be attributed.
CLINICAL SIGNIFICANCE
A profound understanding of the mechanical, wear, and biological properties of the restorative material is imperative for the clinical success of dental restorations. The current study demonstrated superior properties of highly filled injectable composite resins, which imply their wider indications and better long-term clinical performances.
Topics: Composite Resins; Materials Testing; Anti-Bacterial Agents; Streptococcus mutans; Biocompatible Materials; Mice; Animals; Cell Survival; Surface Properties; Dental Materials; Compomers; Water; Nanocomposites; Flexural Strength; Injections; Polymethyl Methacrylate
PubMed: 38697507
DOI: 10.1016/j.jdent.2024.105025 -
Journal of Plastic, Reconstructive &... Jun 2024Chest-wall sarcomas are treated with extensive resections and complex defect reconstruction to restore chest-wall integrity. It is a difficult surgical procedure that...
Resection to restoration: Assessing the synergy of polypropylene mesh (Marlex®) combined with methyl-methacrylate and latissimus dorsi flap for primary chest wall sarcomas.
BACKGROUND
Chest-wall sarcomas are treated with extensive resections and complex defect reconstruction to restore chest-wall integrity. It is a difficult surgical procedure that incorporates a multidisciplinary approach for the best outcome, preventing paradoxical chest movement issues and reducing complications.
OBJECTIVE
We aimed to describe our experience of chest-wall reconstruction using polypropylene mesh (Marlex® Mesh) combined with methyl-methacrylate and soft-tissue coverage with a latissimus dorsi flap following sarcoma resection.
PATIENTS AND METHODS
Among the 53 patients treated for primary chest-wall sarcomas at the European Institute of Oncology (IEO) in Milan, Italy, from 1998 to 2020, 14 cases underwent chest-wall resection and reconstruction using polypropylene mesh, methyl-methacrylate and the latissimus dorsi flap. Patients with locally advanced breast cancers, locally advanced lung cancers, squamous cell carcinomas, and other secondary chest-wall malignancies were excluded from the study, as were the patients with different types of chest-wall reconstruction.
RESULTS
In this study, 14 patients (6 men and 8 women) with various primary chest-wall sarcomas were enrolled. On an average, 2 ribs (range: 1-5) were removed during the surgeries, and the chest-wall defects ranged from 20 to 150 cm with an average size of 73 cm. The mean follow-up period for these patients was approximately 63.80 months CONCLUSION: The combination of Marlex® mesh filled with methyl-methacrylate and covered using latissimus dorsi myocutaneous flap provides safe, low-cost and effective single-stage chest-wall reconstruction after surgery for primary sarcomas.
Topics: Humans; Female; Surgical Mesh; Thoracic Wall; Male; Middle Aged; Sarcoma; Polypropylenes; Plastic Surgery Procedures; Adult; Methylmethacrylate; Aged; Superficial Back Muscles; Thoracic Neoplasms; Surgical Flaps
PubMed: 38691953
DOI: 10.1016/j.bjps.2024.04.022 -
The Bone & Joint Journal May 2024Refobacin Bone Cement R and Palacos + G bone cement were introduced to replace the original cement Refobacin Palacos R in 2005. Both cements were assumed to behave in a... (Randomized Controlled Trial)
Randomized Controlled Trial Comparative Study
AIMS
Refobacin Bone Cement R and Palacos + G bone cement were introduced to replace the original cement Refobacin Palacos R in 2005. Both cements were assumed to behave in a biomechanically similar fashion to the original cement. The primary aim of this study was to compare the migration of a polished triple-tapered femoral stem fixed with either Refobacin Bone Cement R or Palacos + G bone cement. Repeated radiostereometric analysis was used to measure migration of the femoral head centre. The secondary aims were evaluation of cement mantle, stem positioning, and patient-reported outcome measures.
METHODS
Overall, 75 patients were included in the study and 71 were available at two years postoperatively. Prior to surgery, they were randomized to one of the three combinations studied: Palacos cement with use of the Optivac mixing system, Refobacin with use of the Optivac system, and Refobacin with use of the Optipac system. Cemented MS30 stems and cemented Exceed acetabular components were used in all hips. Postoperative radiographs were used to assess the quality of the cement mantle according to Barrack et al, and the position and migration of the femoral stem. Harris Hip Score, Oxford Hip Score, Forgotten Joint Score, and University of California, Los Angeles Activity Scale were collected.
RESULTS
Median distal migration (y-axis) at two years for the Refobacin-Optivac system was -0.79 mm (-2.01 to -0.09), for the Refobacin-Optipac system was -0.75 mm (-2.16 to 0.20), and for the Palacos-Optivac system was -1.01 mm (-4.31 to -0.29). No statistically significant differences were found between the groups. Secondary outcomes did not differ statistically between the groups at the two-year follow-up.
CONCLUSION
At two years, we found no significant differences in distal migration or clinical outcomes between the three groups. Our data indicate that Refobacin Bone Cement R and Palacos + G are comparable in terms of stable fixation and early clinical outcomes.
Topics: Humans; Bone Cements; Male; Female; Prospective Studies; Arthroplasty, Replacement, Hip; Aged; Middle Aged; Hip Prosthesis; Radiostereometric Analysis; Prosthesis Failure; Prosthesis Design; Patient Reported Outcome Measures; Aged, 80 and over; Polymethyl Methacrylate
PubMed: 38688480
DOI: 10.1302/0301-620X.106B5.BJJ-2023-0999.R1 -
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 -
Orthopaedics & Traumatology, Surgery &... Apr 2024Chest wall reconstruction in children after large resection of tumors may be performed with rigid or soft materials. Cementoplasty is commonly used with the "Sandwich"...
INTRODUCTION
Chest wall reconstruction in children after large resection of tumors may be performed with rigid or soft materials. Cementoplasty is commonly used with the "Sandwich" method i.e. gore-tex meshes surrounding both faces of the cement.
HYPOTHESIS
Is antibiotic loaded single-side gore-tex "Tartine" methyl-methacrylate cementoplasty an interesting alternative to the double-side "sandwich" method for chest wall reconstruction?
MATERIAL AND METHODS
Consecutive patients who were treated from 2011 to 2023 in our hospital were included.
RESULTS
Among the ten children treated with a median 5.6 years follow-up, there were no surgical complications related to the reconstruction, loss of function, infections, post operative complications (versus 22.7% in meta-analysis encompassing the 50 rigid reconstructions reported worldwide) nor scoliosis (versus 25%). Three patients have an asymmetric chest wall appearance.
DISCUSSION
"Tartine" cementoplasty is a simple, low-cost technique for pediatric chest wall reconstruction. It is well tolerated and checks key demands for chest wall reconstructions.
LEVEL OF EVIDENCE
IV; retrospective case series.
PubMed: 38657749
DOI: 10.1016/j.otsr.2024.103895 -
Journal of Dentistry Jun 2024This study aimed to compare the physical and mechanical properties of four denture base materials: Polyan IC (PA), milled polymethylmethacrylate (PMMA),... (Comparative Study)
Comparative Study
OBJECTIVES
This study aimed to compare the physical and mechanical properties of four denture base materials: Polyan IC (PA), milled polymethylmethacrylate (PMMA), three-dimensional (3D)-printed resin (3DP), and SR Ivocap (SR).
METHODS
Ninety-six samples were prepared and divided into four groups as follows. Group A consisted of 3DP (Asiga DentaBASE, Asiga) fabricated using a manufacturer-recommended 3D printer (Asiga Pro 4k, Asiga). Group B comprised milled PMMA (MP) (Ivotion Base, Ivoclar Vivadent). Group C included PA (BredentSenden), meanwhile, group D involved SR (Ivoclar VivadentSchaan). Cuboid samples (65 mm x 10 mm x 2.5 mm) were used for biaxial flexure strength testing in a universal testing machine (UTM). Cylindrical samples of 20 mm x 40 mm were used for compressive strength testing in a UTM. Additionally, cuboid samples (65 mm x 10 mm x 2.5 mm) were used for Vickers surface hardness testing in a microhardness tester. disk samples (10 mm x 2.5 mm) were employed for color stability testing both in a coffee solution and Coca-Cola, using a digital spectrophotometer. Statistical analyses were performed using one-way analysis of variance and Tukey's post hoc analysis (α=0.05).
RESULTS
MP demonstrated superior compressive strength (p = 0.002) and color stability compared to that exhibited by 3DP (p < 0.001) while displaying similar flexure strength (p = 0.336) and hardness (p = 0.708). MP and PA displayed similar compressive strength (p = 0.081), flexure strength (p = 0.159), and color stability in coke (p = 0.071). However, MP had reduced hardness (p < 0.001) and color stability in coffee (p < 0.001). Moreover, MP demonstrated a higher compressive strength (p < 0.001) than that displayed by SR. However, the flexure strength, hardness, and color stability were similar (p > 0.05). Furthermore, 3DP exhibited comparable compressive strength (p = 0.334) to that of PA but demonstrated significantly lower flexure strength (p = 0.005), hardness (p < 0.001), and color stability (p < 0.001) compared to PA. In comparison to SR, PA had a higher compressive strength (p < 0.001), hardness (p = 0.001), and color stability in coffee (p < 0.001), although they demonstrated similar (p > 0.05) flexure strength and color stability in coke.
CONCLUSIONS
The MP and PA demonstrated superior compressive strength than that exhibited by the other materials tested. The tested materials had similar flexure strengths, except for PA which demonstrated superiority over the 3DP. Among all tested materials, PA exhibited the highest hardness, while the 3DP was the least color-stable.
CLINICAL SIGNIFICANCE
Considering the mechanical properties and color stability, Polyan and milled polymethylmethacrylate are preferred for complete denture fabrication. However, the limited repairability and complex handling of Polyan should be considered.
Topics: Polymethyl Methacrylate; Denture Bases; Materials Testing; Hardness; Dental Materials; Color; Surface Properties; Compressive Strength; Acrylic Resins; Printing, Three-Dimensional; Humans; Stress, Mechanical; Dental Stress Analysis; Flexural Strength
PubMed: 38657724
DOI: 10.1016/j.jdent.2024.104993 -
Physics in Medicine and Biology May 2024. Prompt gamma timing (PGT) uses the detection time of prompt gammas emitted along the range of protons in proton radiotherapy to verify the position of the Bragg peak...
. Prompt gamma timing (PGT) uses the detection time of prompt gammas emitted along the range of protons in proton radiotherapy to verify the position of the Bragg peak (BP). Cherenkov detectors offer the possibility of enhanced signal-to-noise ratio (SNR) due to the inherent physics of Cherenkov emission which enhances detection of high energy prompt gamma rays relative to other induced uncorrelated signals. In this work, the PGT technique was applied to 3 semiconductor material slabs that emit only Cherenkov light for use in a full scale system: a 3 × 3 × 20 mmTlBr, a 12 × 12 × 12 mmTlBr, and a 5 × 5 × 5 mmTlCl.. A polymethyl methacrylate (PMMA) target was exposed to a 67.5 MeV, 0.5 nA proton beam and shifted in 3 mm increments at the Crocker nuclear laboratory (CNL) in Davis, CA, USA. A fast plastic scintillator coupled to a photomultiplier tube (PMT) provided the start reference for the proton time of flight. Time of flight (TOF) distributions were generated using this reference and the gamma-ray timestamp in the Cherenkov detector.. The SNR of the proton correlated peaks relative to the background was 20, 29, and 30 for each of the three samples, respectively. The upper limit of the position resolutions with the TlCl sample were 2 mm, 3 mm, and 5 mm for 30k, 10k, and 5k detected events, respectively. The time distribution of events with respect to the reference reproduced with clarity the periodicity of the beam, implying a very high SNR of the Cherenkov crystals to detect prompt gammas. Background presence from the neutron-induced continuum, prompt gammas from deuterium, or positron activation were not observed. Material choice and crystal dimensions did not seem to affect significantly the outcome of the results.. These results show the high SNR of the pure Cherenkov emitters TlBr and TlCl for the detection of prompt gammas in a proton beam with current of clinical significance and their potential for verifying the proton range. The accuracy in determining shifts of the BP was highly dependent on the number of events acquired, therefore, the performance of these detectors are expected to vary with different beam conditions such as current, pulse repetition, and proton bunch width.
Topics: Gamma Rays; Time Factors; Proton Therapy; Thallium; Lutetium; Protons; Polymethyl Methacrylate
PubMed: 38657638
DOI: 10.1088/1361-6560/ad4304