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1.
Zhongguo Gu Shang ; 33(9): 831-6, 2020 Sep 25.
Artigo em Chinês | MEDLINE | ID: mdl-32959570

RESUMO

OBJECTIVE: From the perspective of clinical application to analyze the effectiveness and reliability of CPC/PMMA bone cement in percutaneous kyphoplasty (PKP) for the treatment of elderly patients with osteoporotic thoracolumbar fractures. METHODS: A retrospective analysis was performed on 62 patients with osteoporotic compression fracture of single-vertebral thoracic or lumbar segment who underwent PKP surgery and had a bone density less than or equal to -3.0 SD from February 2016 to December 2016. Among them, 23 patients were in CPC/PMMA group, with an average age of (77.6±2.2) years old, 39 patients in PMMA group, with an average age of (77.1±1.1) years old. The indexes between two groups were compared, including the visual analogue scale (VAS), height ratio of anterior vertebra (AVHR), local Cobb angle, cement leakage, new adjacent vertebral fracture(NAVF). RESULTS: There were no significant difference in gender, age, follow-up time and preoperative VAS, AVHR, local Cobb angle between two groups (P>0.05), at the 1 day after operation, VAS, AVHR, local Cobb angle in all patients got obvious improvement (P<0.05), which was no significant difference at 1 day after operation and final follow-up (P>0.05). At the same time, there was no statistically significant difference in the incidence of new adjacent vertebral fracture and cement leakage (P>0.05). The pain in both groups continued to improve at follow up after operation (P<0.05), the local Cobb angle increased (P<0.05) and AVHR decreased slightly (P<0.05). However, the images of conventional methods (X-ray or CT) could not find signs about CPC degeneration and new bone ingrowth. CONCLUSION: CPC/PMMA composite bone cement is safe and reliablein PKP for treatment of elderly patients with osteoporotic thoracolumbar fractures, which can effectively relieve pain and maintain vertebral body stability. It has the same curative effect as PMMA bone cement. It was worthy to research more in future, although no direct evidences support the CPC/PMMA composite bone cement can reduce the incidence of adjacent vertebral fracture, CPC degeneration or new bone ingrowth.


Assuntos
Fraturas por Compressão , Cifoplastia , Fraturas por Osteoporose , Fraturas da Coluna Vertebral , Vertebroplastia , Idoso , Cimentos para Ossos , Fosfatos de Dinucleosídeos , Humanos , Polimetil Metacrilato , Reprodutibilidade dos Testes , Estudos Retrospectivos , Resultado do Tratamento
2.
J Oral Sci ; 62(4): 420-422, 2020 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-32908079

RESUMO

This study compared the mechanical properties and molecular distribution of a polymethyl methacrylate (PMMA) block (Dry) with specimens that were fabricated by a conventional method and cured in a wet environment (Control). Two specimen types were fabricated with heat-curing denture base resin. Dry specimens were polymerized at high pressure and in a dry system, while Control specimens were polymerized with a heat-curing method, in accordance with the manufacturer's recommended procedures. Specimens from each group were evaluated for three-point bending, water sorption and solubility, and color change, and by gel permeation chromatography (GPC). Mean values for the flexural strengths and moduli of the Dry specimens were significantly higher than those of the Control specimens (P > 0.05). Water sorption and discoloration values of the Dry group were significantly lower than those of the Control group. Mean weight-average molecular weights of the Dry group were higher than those of the Control group. As compared with the conventional method, the present method of fabricating PMMA blocks under high pressure yields superior mechanical properties for the denture base.


Assuntos
Desenho Assistido por Computador , Polimetil Metacrilato , Bases de Dentadura , Dentaduras , Teste de Materiais , Estresse Mecânico , Propriedades de Superfície
3.
Dental Press J Orthod ; 25(3): 31-38, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32844970

RESUMO

INTRODUCTION: Orthodontic treatment for adults is currently increasing, and therefore the need to bond brackets to restorations and temporary crowns. The use of CAD/CAM PMMA provisional restorations for orthodontic purposes have not yet been described, and there is currently insufficient information regarding the strength of bracket adhesion. OBJECTIVE: This study aimed at evaluating the effects of thermocycling (TC) and surface treatment on shear bond strength (SBS) of brackets to different provisional materials. METHODS: Forty specimens were made from each material [PMMA (Telio Lab), bis-acryl (Telio CS C&B), and PMMA CAD/CAM (Telio CAD)], sandpapered, and divided according to surface treatment (pumiced or sandblasted) and TC (half of the samples = 1,000 cycles, 5°C/55°C water baths) (n = 10/group). Stainless-steel brackets were bonded to the specimens (using Transbond XT), and SBS testing was performed. Data were analyzed by three-way ANOVA and LSD post-hoc tests (α = 0.05). Failure types were classified with adhesive remnant index (ARI) scores. RESULTS: SBS values ranged from 1.5 to 14.9 MPa. Sandblasted bis-acryl and sandblasted auto-curing PMMA groups presented similar values (p> 0.05), higher than the CAD/CAM material (p< 0.05), with or without TC. When thermocycled, pumiced bis-acryl showed higher SBS than pumiced acrylic (p= 0.005) and CAD/CAM materials (p= 0.000), with statistical difference (p= 0.009). TC showed negative effect (p< 0.05) for sandblasted bis-acryl and pumiced acrylic groups. ARI predominant score was mostly zero (0) for CAD/CAM, 1 and 2 for bis-acryl, and 1 for acrylic groups. CONCLUSION: In general, bis-acryl material showed the highest SBS values, followed by acrylic and CAD/CAM materials, which showed SBS values lower than an optimum strength for bonding brackets.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Análise do Estresse Dentário , Teste de Materiais , Polimetil Metacrilato , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
4.
Artigo em Japonês | MEDLINE | ID: mdl-32814736

RESUMO

PURPOSE: The purpose of this study was to improve the accuracy of dose-distribution calculations by understanding how the calculated dose varies with the change in the relative electron density replacing polymethyl methacrylate (PMMA) in patient-specific quality assurance. METHOD: We calculated the relative electron density at which dose attenuation in each dose calculation algorithm coincides with the measured value of the dose attenuation of single-field irradiation. Next, the dose change was calculated by changing the relative electron density or physical electron density for substituting PMMA for each X-ray energy and calculation algorithm. Furthermore, using clinical plans, changes in point-dose verification and dose-distribution verification that occurred when the relative electron density or physical electron density was varied were investigated. RESULTS: The dose attenuation varies depending on the dose-calculation algorithm, and the optimum value of the electron density is different for each. After the electron density optimization, the point dose verification using the 97.1% to 98.3% (3%/3 mm), 90.0% to 94.3% (2%/3 mm) and gained a dominant improvement tendency (P<0.001). CONCLUSIONS: We clarified dose change accompanying relative electron density or physical electron density change. We concluded that the accuracy of dose-distribution calculation for verification improves by replacing PMMA with optimal relative electron density or physical electron density.


Assuntos
Elétrons , Polimetil Metacrilato , Algoritmos , Humanos , Imagens de Fantasmas , Radiometria , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador
5.
Lab Chip ; 20(19): 3560-3568, 2020 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-32844858

RESUMO

A miniaturized polymerase chain reaction (PCR) system is not only important for medical applications in remote areas of developing countries, but also important for testing at ports of entry during global epidemics, such as the current outbreak of the coronavirus. Although there is a large number of PCR sensor systems available for this purpose, there is still a lack of portable digital PCR (dPCR) heating systems. Here, we first demonstrated a portable plasmonic heating-based dPCR system. The device has total dimensions of 9.7 × 5.6 × 4.1 cm and a total power consumption of 4.5 W, allowing for up to 25 dPCR experiments to be conducted on a single charge of a 20 000 mAh external battery. The dPCR system has a maximum heating rate of 10.7 °C s-1 and maximum cooling rate of 8 °C s-1. Target DNA concentrations in the range from 101 ± 1.4 copies per µL to 260 000 ± 20 000 copies per µL could be detected using a poly(dimethylsiloxane) (PDMS) microwell membrane with 22 080 well arrays (20 µm diameter). Furthermore, the heating system was demonstrated using a mass producible poly(methyl methacrylate) PMMA microwell array with 8100 microwell arrays (80 µm diameter). The PMMA microwell array could detect a concentration from 12 ± 0.7 copies per µL to 25 889 ± 737 copies per µL.


Assuntos
Reação em Cadeia da Polimerase/instrumentação , Algoritmos , Técnicas Biossensoriais , DNA/química , Fontes de Energia Elétrica , Humanos , Membranas Artificiais , Miniaturização , Polimetil Metacrilato
6.
Bone Joint J ; 102-B(6_Supple_A): 163-169, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32475280

RESUMO

AIMS: The aim of this study was to determine if the local delivery of vancomycin and tobramycin in primary total knee arthroplasty (TKA) can achieve intra-articular concentrations exceeding the minimum inhibitory concentration thresholds for bacteria causing acute prosthetic joint infection (PJI). METHODS: Using a retrospective single-institution database of all primary TKAs performed between January 1 2014 and May 7 2019, we identified patients with acute PJI that were managed surgically within 90 days of the initial procedure. The organisms from positive cultures obtained at the time of revision were tested for susceptibility to gentamicin, tobramycin, and vancomycin. A prospective study was then performed to determine the intra-articular antibiotic concentration on postoperative day one after primary TKA using one of five local antibiotic delivery strategies with tobramycin and/or vancomycin mixed into the polymethylmethacrylate (PMMA) or vancomycin powder. RESULTS: A total of 19 patients with acute PJI after TKA were identified and 29 unique bacterial isolates were recovered. The mean time to revision was 37 days (6 to 84). Nine isolates (31%) were resistant to gentamicin, ten (34%) were resistant to tobramycin, and seven (24%) were resistant to vancomycin. Excluding one Fusobacterium nucleatum, which was resistant to all three antibiotics, all isolates resistant to tobramycin or gentamicin were susceptible to vancomycin and vice versa. Overall, 2.4 g of tobramycin hand-mixed into 80 g of PMMA and 1 g of intra-articular vancomycin powder consistently achieved concentrations above the minimum inhibitory concentrations of susceptible organisms. CONCLUSION: One-third of bacteria causing acute PJI after primary TKA were resistant to the aminoglycosides commonly mixed into PMMA, and one-quarter were resistant to vancomycin. With one exception, all bacteria resistant to tobramycin were susceptible to vancomycin and vice versa. Based on these results, the optimal cover for organisms causing most cases of acute PJI after TKA can be achieved with a combination of tobramycin mixed in antibiotic cement, and vancomycin powder. Cite this article: Bone Joint J 2020;102-B(6 Supple A):163-169.


Assuntos
Antibacterianos/administração & dosagem , Artroplastia do Joelho , Bactérias/efeitos dos fármacos , Prótese do Joelho/efeitos adversos , Infecções Relacionadas à Prótese/tratamento farmacológico , Infecções Relacionadas à Prótese/etiologia , Tobramicina/administração & dosagem , Vancomicina/administração & dosagem , Administração Tópica , Cimentos para Ossos , Combinação de Medicamentos , Humanos , Testes de Sensibilidade Microbiana , Polimetil Metacrilato , Estudos Retrospectivos , Tobramicina/farmacologia , Vancomicina/farmacologia
7.
Waste Manag ; 113: 51-61, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32505975

RESUMO

Much attention has been devoted to disposing traditional-sized poly(methyl methacrylate) (PMMA) waste by pyrolysis for methyl methacrylate (MMA). The pyrolysis of micron-sized PMMA waste, which may be different from that of traditional-sized PMMA waste, received little concern. The present study investigated the kinetics and volatile products of micron-sized PMMA waste pyrolysis in inert atmosphere using thermogravimetry and Fourier transform infrared analysis. A global optimization algorithm namely Shuffled Complex Evolution (SCE) was employed to simultaneously optimize the kinetic parameters. Results indicated that one shoulder and one peak occurred in the MLR variations with temperature. The values of the MLR at the shoulder and peak, the average MLR all increased with the heating rate. The optimized kinetic parameters by SCE can be utilized to well reproduce the experimental thermogravimetric data. The values of activation energy and natural logarithm of pre-exponential factor were in the range of 235.95-248.61 kJ/mol and 16.96-28.76 min-1, respectively. The value of activation energy of micron-sized PMMA waste pyrolysis under the present study was greater than that of the traditional-sized PMMA pyrolysis in the previous studies. MMA and CO2 were the major volatile products generated from the micron-sized PMMA waste pyrolysis. The volatile products yield at peak was much larger than that at shoulder. The MMA and CO2 yield were in the range of 87.98-93.54% and 6.46-12.02%, respectively. High MMA yield may be obtained from the pyrolysis of micron-sized PMMA waste in inert atmosphere by appropriately increasing the heating rate adopted in the reactors in the practical applications.


Assuntos
Polimetil Metacrilato , Pirólise , Análise de Fourier , Cinética , Termogravimetria
8.
J Contemp Dent Pract ; 21(3): 285-290, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32434976

RESUMO

AIM: The purpose of this in vitro research is to chemically characterize polymethyl methacrylate (PMMA) processed with 10% and 20% (v/v) tricyclodecane dimethanol diacrylate (TCDDMDA) comonomer. It also aimed to assess the degree of conversion (DC) and glass transition temperature (Tg) of the formed copolymers. MATERIALS AND METHODS: The experimental groups were processed with the TCDDMDA comonomer (10% and 20% v/v), whereas the control group was processed only with the methyl methacrylate monomer. The copolymerization was studied by nuclear magnetic resonance (NMR) spectroscopy. The surface characteristics and composition (wt%) were studied by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy (cuboidal specimen; 5 mm × 5 mm × 3 mm), respectively. The DC and Tg of the formed copolymers (powdered form) were analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry, respectively. One-way analysis of variance with post hoc Bonferroni test was used to compare the mean values of DC% and Tg among the groups. RESULTS: The newly formed copolymer [P(MMA-co-TCDDMDA)] was chemically characterized by NMR and FESEM-EDX. The DC and Tg of the experimental groups were higher than the control. Tricyclodecane dimethanol diacrylate at 20% (v/v) concentration showed the highest DC and Tg. CONCLUSION: The addition of TCDDMDA comonomer improved the DC and Tg of the formed copolymer. CLINICAL SIGNIFICANCE: The P(MMA-co-TCDDMDA) copolymer is expected to improve the mechanical properties and biocompatibility of the denture base acrylic resin. This would result in improved denture quality and durability, thereby, imparting a better quality of life to the geriatric population.


Assuntos
Temperatura Alta , Polimetil Metacrilato , Idoso , Bases de Dentadura , Humanos , Teste de Materiais , Qualidade de Vida
9.
J Prosthodont ; 29(5): 422-428, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32233047

RESUMO

PURPOSE: To evaluate and compare the surface properties (roughness and hardness) of poly(methylmethacrylate) denture base material modified with zirconium dioxide (ZNPs), silicon dioxide (SNPs), and diamond (DNPs) nanoparticles. MATERIALS AND METHODS: Two hundred sixty heat-polymerized acrylic resin disks (15 × 2 mm) were prepared. ZNPs, SNPs, and DNPs were added in concentrations of 0%, 0.5%, 1.0%, 2.5%, and 5.0% by weight of acrylic powder. This yielded a total of 13 groups for each test according to filler type and concentration (n = 10/group). The control group was made of pure acrylic. A mechanical polisher was used to standardize specimens' surfaces before testing. A profilometer and Vickers hardness indenter were used to test the surface roughness and hardness, respectively. ANOVA and Tukey post hoc tests were used for data analysis (α = 0.05). RESULTS: In comparison to control, results showed a nonsignificant increase in surface roughness (Ra ) of acrylic material after the addition of 0.5% nanoparticles (ZNPs p = 0.168, SNPs p = 0.166, and DNPs p = 0.177), while a significant increase was seen with all other concentrations (p ˂ 0.05). Ra values of ZNP and DNP groups were significantly higher than those of the SNPs group (p < 0.001). The addition of any of the fillers to acrylic denture base materials significantly increased the hardness (p ˂ 0.05), with ZNPs and DNPs having values lower than those of the SNPs group (p < 0.001). CONCLUSIONS: Although nanofiller addition increased the hardness of denture base material, Ra was adversely affected when the concentration exceeded 0.5%. Therefore, 0.5% is suggested to be the most appropriate ratio to improve hardness with acceptable Ra .


Assuntos
Nanopartículas , Polimetil Metacrilato , Bases de Dentadura , Dureza , Teste de Materiais , Propriedades de Superfície
10.
Sci Total Environ ; 726: 138547, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32320882

RESUMO

Due to their small size, nanoplastics (NPLs) possess specific properties which can potentiate their toxicity towards aquatic organisms. As primary producers, microalgae are at the base of aquatic food chains, thus negative impacts of NPLs will likely lead to disturbances in ecosystem productivity. The majority of data available on the toxicity of NPLs is limited to polystyrene and green microalgae, leaving a significant lack of knowledge on impacts of other polymer types across different taxonomic groups. So, the main objective of this study was to evaluate the cell responses of the red microalgae Rhodomonas baltica to plain and carboxylated poly(methyl methacrylate) NPLs (PMMA and PMMA-COOH, 50 nm). Results showed different NPL behaviour in media over time, with PMMA forming micro-scale aggregates and PMMA-COOH maintaining its nominal size range. PMMA caused a higher impact in cellular and physiological parameters than PMMA-COOH, even though a decrease in algal growth was only seen for the later. Overall, PMMA caused a significant decrease in cell viability followed by an increase in cell size and complexity, overproduction of pigments, loss of membrane integrity, hyperpolarization of the mitochondrial membrane, increased production of ROS and LPO, decrease in DNA content and reduced photosynthetic capacity. Conversely, a decrease in algal growth for PMMA-COOH was connected to an impairment in cell cycle and consequent decrease in cell viability, metabolic activity and photosynthetic performance, with negligible effects in ROS formation and pigments content. This study provided a first insight into the mechanistic understanding of the toxic impacts of PMMA and PMMA-COOH NPLs in red microalgae. Results obtained suggest an interaction between both NPLs and R. baltica cell surface that is dependent on particle behaviour and surface chemistry. Future experiments focusing on the in-depth characterization of the mode of action of these particles are recommended.


Assuntos
Microalgas , Poluentes Químicos da Água , Ecossistema , Polimetil Metacrilato , Poliestirenos
12.
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi ; 34(4): 435-441, 2020 Apr 15.
Artigo em Chinês | MEDLINE | ID: mdl-32291977

RESUMO

Objective: To compare the effect of percutaneous kyphoplasty (PKP) with different phases bone cement for treatment of osteoporotic vertebral compression fracture (OVCF). Methods: The clinical data of 219 OVCF patients who treated with PKP and met the selection criteria between June 2016 and May 2018 were retrospectively analyzed. According to the different time of intraoperative injection of bone cement, they were divided into observation group [116 cases, intraoperative injection of polymethyl methacrylate (PMMA) bone cement in low-viscosity wet-sand phase)] and control group (103 cases, intraoperative injection of PMMA bone cement in low-viscosity wire-drawing phase). There was no significance in general date of gender, age, disease duration, body mass index, bone mineral density T value, fracture vertebral body, preoperative fracture severity of the responsible vertebral body, anterior height ratio of the responsible vertebral body, preoperative pain visual analogue scale (VAS) score, and Oswestry disability index (ODI) between the two groups ( P>0.05). The VAS score and ODI score were used to evaluate the improvement of patients' symptoms at immediate, 2 days, 3 months after operation and at last follow-up. At 1 day, 3 months after operation, and at last follow-up, X-ray film and CT of spine were reexamined to observe the distribution of bone cement in the vertebral body, bone cement leakage, and other complications. During the follow-up, the refracture rate of the responsible vertebral body and the fracture rate of the adjacent vertebral body were recorded. Results: The injection amount of bone cement in the observation group and control group were (4.53±0.45) mL and (4.49±0.57) mL, respectively, showing no significant difference between the two groups ( t=1.018, P=0.310). Patients in both groups were followed up 6-18 months (mean, 13.3 months). There were 95 cases (81.9%) and 72 cases (69.9%) of the bone cement distribution range more than 49% of the cross-sectional area of the vertebral body in the observation group and the control group, respectively, showing significant difference in the incidence between the two groups ( χ 2=4.334, P=0.037). The VAS score and ODI score of the postoperative time points were significantly improved compared with those before operation ( P<0.05), and there were significant differences among the postoperative time points ( P<0.05). The VAS score and ODI score of the observation group were significantly better than those of the control group ( P<0.05) at immediate, 2 days, and 3 months after operation, and there was no significant difference between the two groups at last follow-up ( P>0.05). At 1 day after operation, the cement leakage occurred in 18 cases of the observation group (8 cases of venous leakage, 6 cases of paravertebral leakage, 4 cases of intradiscal leakage) and in 22 cases of the control group (9 cases of venous leakage, 8 cases of paravertebral leakage, 5 cases of intradiscal leakage). There was no significant difference between the two groups ( P>0.05). During the follow-up, 5 cases (4.3%) in the observation group, 12 cases (11.7%) in the control group had responsible vertebral refracture, and 6 cases (5.2%) in the observation group and 14 cases (13.6%) in the control group had adjacent vertebral fracture, the differences were significant ( χ 2=4.105, P=0.043; χ 2=4.661, P=0.031). Conclusion: Bone cement injection with wet-sand phase in PKP is beneficial for the bone cement evenly distributed, strengthening the responsible vertebral, relieving the short-term pain after operation, decreasing the rate of responsible vertebral refracture and adjacent vertebral fracture without increasing the incidence of relevant complications and can enhance the effectiveness.


Assuntos
Cimentos para Ossos , Fraturas por Compressão/cirurgia , Cifoplastia , Fraturas por Osteoporose/cirurgia , Fraturas da Coluna Vertebral/cirurgia , Humanos , Polimetil Metacrilato , Estudos Retrospectivos , Resultado do Tratamento
13.
J Oral Maxillofac Surg ; 78(7): 1191.e1-1191.e8, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32277939

RESUMO

PURPOSE: Augmentation of the occiput is an esthetic procedure that is gaining more popularity but is not well reported in the literature. The aim of this retrospective study on a case series of patients was to describe the use of computer-aided design-computer-aided manufacturing prefabricated polymethyl methacrylate (PMMA) implants in esthetic occipital augmentation. Furthermore, comparison between the surgical outcome and the digital planning was carried out to ascertain the replicability of the surgical planning. MATERIALS AND METHODS: We performed a retrospective study of a case series of patients who underwent occipital augmentation with computer-aided design-computer-aided manufacturing prefabricated implants. Customized PMMA occipital implants were fabricated and were inserted via a bicoronal approach with patients under general anesthesia. The patients' 1-week postoperative cone-beam computed tomography image was superimposed onto the preoperative virtual planning images, and the positions of the actual implant and virtual implant were compared. RESULTS: A total of 15 patients who were treated at Charm Clinic, Taipei, Taiwan, and received occipital implants for esthetic purposes were included in this study. The percentage overlap of the occipital implant ranged from 87.8% to 99.99% (mean, 95.71%). One patient experienced partial wound dehiscence, which recovered after wound revision and suturing. In another patient, mild hematoma developed, which resolved spontaneously. Although no formal questionnaire was administered, all patients expressed satisfaction with the cosmetic outcome. CONCLUSIONS: The use of prefabricated PMMA posterior calvarial implants showed a rate of replicability of 87.8% to 99.99% (mean, 95.71%) compared with the preoperative virtual planning, and we recommend it as a feasible method for esthetic occipital augmentation.


Assuntos
Implantes Dentários , Cirurgia Assistida por Computador , Desenho Assistido por Computador , Estética , Humanos , Imageamento Tridimensional , Polimetil Metacrilato , Estudos Retrospectivos , Taiwan
14.
J Clin Neurosci ; 76: 219-225, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32265080

RESUMO

Whilst surgical resection is traditionally used for the successful eradication of locally aggressive osseous tumors, it is often hazardous or unachievable, particularly in complex anatomic sites, such as the pelvis and spine. The authors present the use of microwave ablation in combination with Zoledronic acid (ZA) administration, alone and with the use of ZA-loaded polymethyl methacrylate (PMMA) to percutaneously treat unresectable bone tumors in 4 patients with giant cell tumors (GCT), multiple myeloma (MM) and breast cancer metastasis.


Assuntos
Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/radioterapia , Cementoplastia/métodos , Micro-Ondas/uso terapêutico , Ácido Zoledrônico/uso terapêutico , Adolescente , Adulto , Idoso , Neoplasias Ósseas/secundário , Feminino , Humanos , Masculino , Mieloma Múltiplo , Pelve , Polimetil Metacrilato , Terapia por Radiofrequência , Coluna Vertebral
15.
J Prosthodont ; 29(8): 686-692, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32333442

RESUMO

PURPOSE: To investigate the effect of 254-nm ultraviolet light on the viability of Candida albicans biofilm on poly(methylmethacrylate). METHODS: Poly(methylmethacrylate) specimens (1 cm × 1 cm × 1 mm) were placed in 6-well culture plates. Each well contained 8 ml of 104 colony forming units/milliliter of C. albicans ATCC90028 and Sabouraud dextrose broth. Plates were incubated at 37°C for 24 hours. Specimens were then divided into 11 groups (n = 4): no treatment control groups, 3.8% sodium perborate immersion for 5 minutes (PP5m) and for 12 hours (PO12h), and 6 groups exposed to ultraviolet light for 5, 15, 30, 60, 120 or 300 seconds separately using UVP XX-15S series lamps. After sonication, cell suspensions were plated, and colony-forming units were counted. The relationship between survival of C. albicans and ultraviolet light irradiation energy exposure was analyzed and compared to the survival of sodium perborate groups. The effect of disinfection treatments and ultraviolet light energy exposure on C. albicans survival was analyzed with ANOVA (alpha = 0.05). RESULTS: There was a significant decrease in C. albicans survival with increasing ultraviolet light energy exposure (p = 0.00001, p < 0.05) Survival vs. immersion exposure time analysis of chemical disinfection showed no survival of C. albicans in groups PP5m and PO12h. C. albicans in the UV 300s group with energy of 210 mJ/cm2 (71 CFU/ml) showed a statistical difference from that of two chemical immersion groups (PP5m, PO12h = 0 CFU/ml) (p = 0.00001, p < 0.05). CONCLUSION: Ultraviolet 254 nm irradiation demonstrated a significant inhibition of C. albicans survival on poly(methylmethacrylate) samples. Ultraviolet light exposure of 300 seconds inhibited the survival of C. albicans close to the level of 3.8% sodium perborate treatment.


Assuntos
Candida albicans , Polimetil Metacrilato , Resinas Acrílicas , Biofilmes , Propriedades de Superfície , Raios Ultravioleta
16.
J Prosthet Dent ; 123(4): 647.e1-647.e7, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32115217

RESUMO

STATEMENT OF PROBLEM: Artificial denture teeth made of polymethyl methacrylate (PMMA) resin have good adhesion to the denture base but are relatively soft and have limited wear resistance during function. PURPOSE: The purpose of this in vitro study was to evaluate the influence of the addition of 2 inorganic nanofillers on the flexural strength, maximal displacement, elastic modulus, Isolde impact resistance, and Brinell hardness of acrylic resin denture teeth. MATERIAL AND METHODS: Heat polymerizing polymethyl methacrylate resin was mixed with silanized silica or silanized feldspar in concentrations of 5 wt%, 10 wt%, and 15 wt%. The first test was conducted after 24 hours of storage in laboratory conditions, and the second assessment was conducted after 3 months of storage in distilled water at 37 °C. The Brinell hardness was evaluated, and the elastic modulus and maximal displacement at fracture were calculated. The flexural strength and Isolde impact resistance were measured with a 3-point flexural test. Acrylic resin specimens without filler addition were used as a control group. Statistical analysis included 2-way ANOVA for independent variables (α=.05) and the Student t test for time-dependent changes (α=.05). These were performed with Statistica 12 software. RESULTS: The acrylic resin specimens modified with the addition of silanized feldspar had significantly higher Brinell hardness, elastic modulus, maximal displacement, and flexural strength and also had no adverse effect on Isolde impact resistance compared with the conventional acrylic resin. Silica filler increased the Brinell hardness and elastic modulus of acrylic resins but significantly reduced the flexural strength and Isolde impact resistance.


Assuntos
Polimetil Metacrilato , Dióxido de Silício , Silicatos de Alumínio , Materiais Dentários , Bases de Dentadura , Dentaduras , Humanos , Teste de Materiais , Maleabilidade , Compostos de Potássio , Estresse Mecânico , Propriedades de Superfície
17.
Environ Res ; 184: 109332, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32151845

RESUMO

Novel electrospun poly(methyl methacrylate)/polyaniline electrospun fibres were produced, characterised, modified, and used as a support for laccase immobilisation by two methods: adsorption and covalent binding. Effective deposition of laccase by both methods was confirmed by FTIR and CLSM results. Nevertheless, the main objective of the study was to select the most favourable immobilisation conditions and prepare heterogeneous biocatalysts with the best possible catalytic properties. The highest relative activity of enzymes immobilised by adsorption and covalent binding were obtained after 1 h of immobilisation using laccase solution at a concentration of 1 mg/mL, at pH 5 and 25 °C. It was found that the immobilised enzymes, which were present in amounts of 110 mg/g and 185 mg/g for systems with adsorbed and covalently bonded laccase respectively, exhibited slightly lower substrate affinity, and in consequence also a lower maximum reaction rate, than the free enzyme. The stability of laccase improved significantly upon immobilisation: both heterogeneous biocatalysts retained over 80% relative activity even after 10 repeated catalytic cycles and 30 days of storage. The obtained systems were used for decolourisation of Remazol Brilliant Blue R dye from a model aqueous solution, resulting in removal efficiencies of 87% and 58% using adsorbed and covalently bonded laccase, respectively. The described approach to the removal of textile dye from model solution is significant for the sustainable and environmentally friendly decolourisation of various compounds from wastewater.


Assuntos
Corantes , Lacase , Polimetil Metacrilato , Purificação da Água , Adsorção , Compostos de Anilina
18.
Nat Commun ; 11(1): 879, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32054851

RESUMO

Bio-hybrid light-emitting diodes (Bio-HLEDs) based on color down-converting filters with fluorescent proteins (FPs) have achieved moderate efficiencies (50 lm/W) and stabilities (300 h) due to both thermal- and photo-degradation. Here, we present a significant enhancement in efficiency (~130 lm/W) and stability (>150 days) using a zero-thermal-quenching bio-phosphor design. This is achieved shielding the FP surface with a hydrophilic polymer allowing their homogenous integration into the network of a light-guiding and hydrophobic host polymer. We rationalize how the control of the mechanical and optical features of this bio-phosphor is paramount towards highly stable and efficient Bio-HLEDs, regardless of the operation conditions. This is validated by the relationships between the stiffness of the FP-polymer phosphor and the maximum temperature reached under device operation as well as the transmittance of the filters and device efficiency.


Assuntos
Proteínas de Fluorescência Verde/genética , Luz , Organofosfatos/química , Polimetil Metacrilato/química , Semicondutores , Bioengenharia/métodos , Dicroísmo Circular , Cor , Desenho de Equipamento , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/isolamento & purificação , Mutação , Estrutura Secundária de Proteína/genética , Estrutura Terciária de Proteína/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Temperatura
19.
Dent Mater J ; 39(3): 471-482, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32092720

RESUMO

This study assessed the impact of surface treatments and repair resin reinforcement with zirconium oxide nano-particles (nano-ZrO2) on flexural strength (FS) of repaired denture base. A total of 320 heat-polymerized acrylic resin specimens were prepared and sectioned creating 2-mm gap. According to repair surface treatment, specimens were distributed into four groups: I) methyl methacrylate (M); II) alumina-blasted (AB); III) AB+silane coupling agent (SC); and IV) AB+methacrylate based composite bonding agent (MA). Groups were subdivided into 4 (n=20) according to nano-ZrO2 concentration (0, 2.5, 5, 7.5 wt%). Half the specimens were thermo-cycled before testing. FS was determined by three-point bending test. Statistical analysis was done using ANOVA and Tukey-Kramer multiple comparison tests, with α=0.05. Alumina-blasting+(SC) or (MA) significantly increased FS of repaired specimens compared to control (p<0.05). All surface-treated specimens combined with nano-ZrO2 reinforced repair resin significantly increased FS.


Assuntos
Bases de Dentadura , Polimetil Metacrilato , Resinas Acrílicas , Resistência à Flexão , Teste de Materiais , Maleabilidade , Propriedades de Superfície
20.
Macromol Rapid Commun ; 41(6): e1900582, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32037634

RESUMO

Annealing a supported polymer film in the melt state results in the growth of an irreversibly adsorbed layer, which has been shown to influence thin film properties such as diffusion and glass transition temperature. Adsorbed layer growth is attributed to many simultaneous interactions between individual monomer units and the substrate, stabilizing chains against desorption. In this study, adsorbed layers of polystyrene (PS), poly(methyl methacrylate) (PMMA), and their random copolymers are isolated by select solvents. While PS adsorbed layer thickness is largely unaffected by the choice of washing solvent, the PMMA adsorbed layer completely desorbs when washed with tetrahydrofuran and chloroform, as opposed to toluene. Scaling relationships between adsorbed layer thickness and degree of chain adsorption at the substrate enable the use of adsorbed layer thickness to probe specific polymer-substrate interactions. Composition-dependent desorption trends indicate non-preferential adsorption between styrene and methyl methacrylate repeat units at the substrate, despite differences in substrate interaction strength. This insight contributes to the developing mechanism for the adsorption of random copolymers during melt-state annealing, further extending the ability to predict processing-inducted changes to the properties of polymer thin films to heterogeneous systems.


Assuntos
Polímeros/química , Polimetil Metacrilato/química , Poliestirenos/química , Solventes/química , Adsorção , Clorofórmio/química , Furanos/química , Polímeros/síntese química , Solubilidade , Propriedades de Superfície , Temperatura , Tolueno/química
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