RESUMEN
The use of biopolymers as an alternative to petroleum-based polymers offers a sustainable solution with benefits such as biodegradability and unique functionalities. In this study, starch/zein bioparticles (BPs) obtained by nanoprecipitation were employed to synthesize acrylic polymer/biopolymer waterborne nanoparticles with excellent film formation capability. These hybrid nanoparticle dispersions were obtained through a semibatch emulsion polymerization using the previously synthesized BPs as seed and variable monomeric formulations composed of butyl acrylate and methyl methacrylate. A synergetic effect between acrylic and biopolymer phases was evidenced where the incorporation of BPs had a fundamental role in improving sensitive properties, such as film blocking resistance, while attaining smooth films at room temperature. These excellent film-forming properties of starch/acrylic hybrid latexes without requiring the addition of formulation agents, which depict an important benefit from an environmental viewpoint, demonstrate that they represent a promising alternative for the development of a new generation of eco-friendly binders.
Asunto(s)
Acrilatos , Nanopartículas , Almidón , Almidón/química , Nanopartículas/química , Acrilatos/química , Zeína/química , Polimerizacion , Agua/química , Resinas Acrílicas/químicaRESUMEN
To evaluate the effect of antiseptic soap on single and dual-species biofilms of Candida albicans and Streptococcus mutans on denture base and reline resins. Samples of the resins were distributed into groups (n = 9) according to the prevention or disinfection protocols. In the prevention protocol, samples were immersed in the solutions (Lifebuoy, 0.5% sodium hypochlorite solution and PBS) for 7, 14 and 28 days before the single and dual-species biofilms formation. Overnight denture disinfection was simulated. In the disinfection protocol, samples were immersed in the same solutions during 8 hours after the single and dual-species biofilms formation. Antimicrobial activity was analyzed by counting colony-forming units (CFU/mL) and evaluating cell metabolism. Cell viability and protein components of the biofilm matrix were evaluated using confocal laser scanning microscopy (CLSM). Data were submitted to ANOVA, followed by Tukey's post-test (α = 0.05) or Dunnett's T3 multiple comparisons test. In the prevention protocol, Lifebuoy solution effectively reduced the number of CFU/mL of both species. In addition, the solution decreased the cell metabolism of the microorganisms. Regarding disinfection protocol, the Lifebuoy solution was able of reduce approximately of 2-3 logs for all the biofilms on the denture base and reline resin. Cellular metabolism was also reduced. The images obtained with CLSM corroborate these results. Lifebuoy solution was effective in reducing single and dual-species biofilms on denture base and reline resins.
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Resinas Acrílicas , Biopelículas , Candida albicans , Bases para Dentadura , Streptococcus mutans , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Streptococcus mutans/efectos de los fármacos , Streptococcus mutans/fisiología , Candida albicans/efectos de los fármacos , Candida albicans/fisiología , Bases para Dentadura/microbiología , Resinas Acrílicas/química , Resinas Acrílicas/farmacología , Antiinfecciosos Locales/farmacología , Desinfección/métodos , HumanosRESUMEN
After traumatic brain injury, the brain extracellular matrix undergoes structural rearrangement due to changes in matrix composition, activation of proteases, and deposition of chondroitin sulfate proteoglycans by reactive astrocytes to produce the glial scar. These changes lead to a softening of the tissue, where the stiffness of the contusion "core" and peripheral "pericontusional" regions becomes softer than that of healthy tissue. Pioneering mechanotransduction studies have shown that soft substrates upregulate intermediate filament proteins in reactive astrocytes; however, many other aspects of astrocyte biology remain unclear. Here, we developed a platform for the culture of cortical astrocytes using polyacrylamide (PA) gels of varying stiffness (measured in Pascal; Pa) to mimic injury-related regions in order to investigate the effects of tissue stiffness on astrocyte reactivity and morphology. Our results show that substrate stiffness influences astrocyte phenotype; soft 300 Pa substrates led to increased GFAP immunoreactivity, proliferation, and complexity of processes. Intermediate 800 Pa substrates increased Aggrecan+, Brevican+, and Neurocan+ astrocytes. The stiffest 1 kPa substrates led to astrocytes with basal morphologies, similar to a physiological state. These results advance our understanding of astrocyte mechanotransduction processes and provide evidence of how substrates with engineered stiffness can mimic the injury microenvironment.
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Resinas Acrílicas , Astrocitos , Mecanotransducción Celular , Astrocitos/metabolismo , Animales , Resinas Acrílicas/química , Células Cultivadas , Proteína Ácida Fibrilar de la Glía/metabolismo , Ratas , Geles/química , Proliferación Celular , Ratas Sprague-DawleyRESUMEN
This study investigated the antimicrobial activity of surface pre-reacted glass ionomer eluate (S-PRG) against oral microcosm biofilms collected from the oral cavity of patients. Dental biofilm samples were collected from three volunteers to form microcosm biofilms in vitro. Initially, screening tests were carried out to determine the biofilm treatment conditions with S-PRG eluate. The effects of a daily treatment for 5 min using three microcosm biofilms from different patients was then evaluated. For this, biofilms were formed on tooth enamel specimens for 120 h. Biofilms treated with 100% S-PRG for 5 min per day for 5 days showed a reduction in the number of total microorganisms, streptococci and mutans streptococci. SEM images confirmed a reduction in the biofilm after treatment. Furthermore, S-PRG also reduced lactic acid production. It was concluded that S-PRG eluate reduced the microbial load and lactic acid production in oral microcosm biofilms, reinforcing its promising use as a mouthwash agent.
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Biopelículas , Boca , Biopelículas/efectos de los fármacos , Humanos , Boca/microbiología , Streptococcus mutans/efectos de los fármacos , Streptococcus mutans/crecimiento & desarrollo , Antiinfecciosos/farmacología , Antisépticos Bucales/farmacología , Ácido Láctico/farmacología , Cementos de Ionómero Vítreo/farmacología , Cementos de Ionómero Vítreo/química , Resinas Acrílicas/farmacología , Resinas Acrílicas/química , Streptococcus/efectos de los fármacos , Streptococcus/fisiología , Propiedades de Superficie , Dióxido de SilicioRESUMEN
Cellulose modified hydrogels can be produced directly from raw biopolymers in novel cellulose solvents such as NaOH/urea aqueous solution. The effect of cellulose characteristics on the synthesis of a cellulose-graft-(net-poly(acrylamide-co-acrylic acid)) and its performance as water absorbent/methylene blue dye removal material is analyzed. Three cellulose samples, one analytical grade and two obtained from teak wood sawdust with different pretreatments (one alkaline and the other, a novel one known as (gas phase) acid pretreatment) were compared. The starting raw celluloses were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and viscosity in cupri ethylenediamine hydroxide (CED) solution, whereas the chemically modified materials were characterized by SEM, FTIR, and TGA. The pretreatment used influences composition, crystallinity index and degree of polymerization (DP) of the cellulose obtained. The modified material produced with cellulose from alkaline pretreatment showed the highest swelling ratio in water absorption tests at room temperature (12,714 %); in contrast, the one with cellulose from acid pretreatment showed the lowest swelling ratio (7,470 %). However, this difference is not so significative in dye removal tests, where absorption capacity is 139 and 140 mg/g, respectively. The results indicate that cellulose composition, particularly structures with significant hemicellulose and lignin remaining content, has a major effect on the performance of modified materials for water absorption, and degree of polymerization has a major effect on adsorption capacity of methylene blue.
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Celulosa , Colorantes , Lignina , Agua , Madera , Lignina/química , Celulosa/química , Agua/química , Madera/química , Colorantes/química , Resinas Acrílicas/química , Azul de Metileno/química , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X , Purificación del Agua/métodos , Contaminantes Químicos del Agua/química , Acrilamidas/químicaRESUMEN
Specific products containing natural resources can contribute to the innovation of complete denture hygiene. OBJECTIVE: To conduct an in vitro evaluation of experimental dentifrices containing essential oils of Bowdichia virgilioides Kunth (BvK), Copaifera officinalis (Co), Eucalyptus citriodora (Ec), Melaleuca alternifolia (Ma) and Pinus strobus (Ps) at 1%. METHODOLOGY: The variables evaluated were organoleptic and physicochemical characteristics, abrasiveness (mechanical brushing machine) simulating 2.5 years, and microbial load (Colony Forming Units - CFU/mL), metabolic activity (XTT assay) and cell viability (Live/Dead® BacLight™ kit) of the multispecies biofilm (Streptococcus mutans: Sm, Staphylococcus aureus: Sa, Candida albicans: Ca and Candida glabrata: Cg). Specimens of heat-polymerized acrylic resins (n=256) (n=96 specimens for abrasiveness, n=72 for microbial load count, n=72 for biofilm metabolic activity, n=16 for cell viability and total biofilm quantification) with formed biofilm were divided into eight groups for manual brushing (20 seconds) with a dental brush and distilled water (NC: negative control), Trihydral (PC: positive control), placebo (Pl), BvK, Co, Ec, Ma or Ps. After brushing, the specimens were washed with PBS and immersed in Letheen Broth medium, and the suspension was sown in solid specific medium. The organoleptic characteristics were presented by descriptive analysis. The values of density, pH, consistency and viscosity were presented in a table. The data were analyzed with the Wald test in a generalized linear model, followed by the Kruskal-Wallis test, Dunn's test (mass change) and the Bonferroni test (UFC and XTT). The Wald test in Generalized Estimating Equations and the Bonferroni test were used to analyze cell viability. RESULTS: All dentifrices showed stable organoleptic characteristics and adequate physicochemical properties. CN, Ec, Ps, Pl and PC showed low abrasiveness. There was a significant difference between the groups (p<0.001) for microbial load, metabolic activity and biofilm viability. CONCLUSIONS: It was concluded that the BvK, Ec and Ps dentifrices are useful for cleaning complete dentures, as they have antimicrobial activity against biofilm. The dentifrices containing Bowdichia virgilioides Kunth showed medium abrasiveness and should be used with caution.
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Biopelículas , Dentífricos , Dentadura Completa , Ensayo de Materiales , Aceites Volátiles , Biopelículas/efectos de los fármacos , Dentífricos/farmacología , Dentífricos/química , Aceites Volátiles/farmacología , Aceites Volátiles/química , Dentadura Completa/microbiología , Factores de Tiempo , Reproducibilidad de los Resultados , Cepillado Dental , Recuento de Colonia Microbiana , Staphylococcus aureus/efectos de los fármacos , Estadísticas no Paramétricas , Streptococcus mutans/efectos de los fármacos , Análisis de Varianza , Viabilidad Microbiana/efectos de los fármacos , Candida albicans/efectos de los fármacos , Valores de Referencia , Resinas Acrílicas/química , Resinas Acrílicas/farmacologíaRESUMEN
OBJECTIVE: This study evaluated the surface roughness, wettability and adhesion of multispecies biofilms (Candida albicans, Staphylococcus aureus and Streptococcus mutans) on 3D-printed resins for complete denture bases and teeth compared to conventional resins (heat-polymerized acrylic resin; artificial pre-fabricated teeth). METHODOLOGY: Circular specimens (n=39; 6.0 mm Ø × 2.0 mm) of each group were subjected to roughness (n=30), wettability (n=30) and biofilm adhesion (n=9) tests. Three roughness measurements were taken by laser confocal microscopy and a mean value was calculated. Wettability was evaluated by the contact angle of sessile drop method, considering the mean of the three evaluations per specimen. In parallel, microorganism adhesion to resin surfaces was evaluated using a multispecies biofilm model. Microbial load was evaluated by determining the number of Colony Forming Units (CFU/mL) and by scanning electron microscopy (SEM). Data were subjected to the Wald test in a generalized linear model with multiple comparisons and Bonferroni adjustment, as well as two-way ANOVA (α=5%). RESULTS: The roughness of the conventional base resin (0.01±0.04) was lower than that of the conventional tooth (0.14±0.04) (p=0.023) and 3D-printed base (0.18±0.08) (p<0.001). For wettability, conventional resin (84.20±5.57) showed a higher contact angle than the 3D-printed resin (60.58±6.18) (p<0.001). Higher microbial loads of S. mutans (p=0.023) and S. aureus (p=0.010) were observed on the surface of the conventional resin (S. mutans: 5.48±1.55; S. aureus: 7.01±0.57) compared to the 3D-printed resin (S. mutans: 4.11±1.96; S. aureus: 6.42±0.78). The adhesion of C. albicans was not affected by surface characteristics. The conventional base resin showed less roughness than the conventional dental resin and the printed base resin. CONCLUSION: The 3D-printed resins for base and tooth showed less hydrophobicity and less adhesion of S. mutans and S. aureus than conventional resins.
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Resinas Acrílicas , Adhesión Bacteriana , Biopelículas , Candida albicans , Bases para Dentadura , Ensayo de Materiales , Microscopía Confocal , Microscopía Electrónica de Rastreo , Impresión Tridimensional , Staphylococcus aureus , Streptococcus mutans , Propiedades de Superficie , Humectabilidad , Streptococcus mutans/fisiología , Staphylococcus aureus/fisiología , Candida albicans/fisiología , Bases para Dentadura/microbiología , Resinas Acrílicas/química , Análisis de Varianza , Reproducibilidad de los Resultados , Dentadura Completa/microbiología , Valores de Referencia , Recuento de Colonia Microbiana , Modelos LinealesRESUMEN
STATEMENT OF PROBLEM: The difference in chemical composition between denture base resin and denture teeth requires the development of bonding protocols that increase the union between the materials. PURPOSE: The purpose of this in vitro study was to evaluate the impact of different bonding protocols on the bond between heat-polymerized and 3-dimensionally (3D) printed acrylic resin denture bases and acrylic resin prefabricated and 3D printed artificial teeth. MATERIAL AND METHODS: Four types of artificial teeth were evaluated: prefabricated acrylic resin (VITA MFT) and 3D printed (Cosmos TEMP, PRIZMA 3D Bio Denture, and PrintaX AA Temp) bonded to 20×24-mm cylinders of heat-polymerized (VipiWave) and 3D printed (Cosmos Denture, PRIZMA 3D Bio Denture, and PrintaX BB Base) denture bases. Three bonding protocols were tested (n=20): mechanical retention with perforation + monomer (PT1), mechanical retention with perforation + airborne-particle abrasion with 50-µm aluminum oxide + monomer (PT2), and mechanical retention with perforation + Palabond (PT3). Half of the specimens in each group received 10 000 thermocycles and were then subjected to the bonding test at a crosshead speed of 1 mm/minute. The failure type was analyzed and scanning electron micrographs made. Additionally, surface roughness (Ra) and wettability (degree) were analyzed (n=15). ANOVA was used to evaluate the effect of the bonding protocol, and the Student t test was applied to compare the experimental groups with the control (α=.05). For type of failure, a descriptive analysis was carried out using absolute and relative frequency. The Kruskal-Wallis test was used to evaluate the surface changes (α=.05). RESULTS: Among the protocols, PT3 with in Yller and PT2 with Prizma had the highest bond strengths of the heat-polymerized denture base and 3D printed teeth (P<.05). When comparing the experimental groups with the control, PT3 and PT2 had greater union with the 3D printed denture base + 3D printed teeth (in Yller), with no difference from the heat-polymerized denture base + prefabricated teeth in acrylic resin. The treatment of the 3D printed tooth surfaces affected the surface roughness of Prizma (P<.001) and wettability (P<.001). CONCLUSIONS: To increase the bond between Yller 3D printed denture base + 3D printed teeth, a bonding protocol including mechanical retention with perforation + Palabond or mechanical retention with perforation + airborne-particle abrasion with aluminum oxide + monomer is indicated. For the other materials tested, further bonding protocols need to be investigated.
Asunto(s)
Resinas Acrílicas , Recubrimiento Dental Adhesivo , Bases para Dentadura , Impresión Tridimensional , Diente Artificial , Resinas Acrílicas/química , Recubrimiento Dental Adhesivo/métodos , Técnicas In Vitro , Ensayo de Materiales , Propiedades de Superficie , Humanos , Materiales Dentales/química , Diseño de DentaduraRESUMEN
OBJECTIVE: To evaluate the influence of post-cure heat treatments (PCHT) on Knoop microhardness (KHN) and color change of bis-acryl composite resin (Protemp 4 - 3M ESPE, USA and PrimmaArt - FGM, Brazil) and chemically activated acrylic resins (Dencôr - Clássico, Brazil, and Duralay - Cotia, Brazil). METHODS AND MATERIALS: Specimens (12×1 mm) were prepared for each material (n=10/group). Thirty minutes after curing, the specimens were subjected to PCHT for 10 minutes at 70°, 100°, or 130°C. The control group was kept at room temperature (24°C) for the same amount of time. KHN was analyzed 24 hours after PCHT (n=10). Following Commission Internationale de l'Éclairage (CIE) Delta E 2000 (CIEDE2000 [ΔE00]), color measurements were obtained at three time points: 1. after polymerization; 2. after PCHT; and 3. after 30 days of storage in water, coffee, or red wine. Data for each material were analyzed by one-way analysis of variance (ANOVA) (p<0.05). RESULTS: The PCHT at 130°C produced the highest KHN values. Except for the 70°C groups from Dencôr and Protemp, all PCHTs increased the initial color values (p>0.05). In general, chemically activated acrylic resins showed an increase in color stability when subjected to PCHT (p>0.05). For bis-acryl composite resin, PCHT did not influence color stability (p<0.05). CONCLUSION: Overall, the results showed that PCHT increased the tested materials' color changes and Knoop microhardness. However, except for PCHT at 130°C in Duralay, the color changes remained within acceptable values. The PCHT treatment resulted in better color stability for most of the composite resins studied.
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Resinas Compuestas , Calor , Resinas Compuestas/uso terapéutico , Resinas Compuestas/química , Resinas Acrílicas/química , Polimetil Metacrilato/químicaRESUMEN
OBJECTIVE: The objective was to synthesize halloysite nanotubes loaded with chlorhexidine (HNT/CHX) and evaluate the antimicrobial activity, microhardness, color change, and surface characteristics of an experimental self-curing acrylic resin containing varying concentrations of the synthesized nanomaterial. METHODS: The characterization of HNT/CHX was carried out by calculating incorporation efficiency, morphological and compositional, chemical and thermal evaluations. SAR disks were made containing 0 %, 3 %, 5 %, and 10 % of HNT/CHX. Specimens (n = 3) were immersed in distilled water and spectral measurements were carried out using UV/Vis spectroscopy to evaluate the release of CHX for up to 50 days. The antimicrobial activity of the composite against Candida albicans and Streptococcus mutans was evaluated by disk-diffusion test. Microhardness, color analyses (ΔE), and surface roughness (Ra) (n = 9) were performed before and after 30 days of immersion. Data were analyzed using ANOVA/Bonferroni. {Results.} The incorporation efficiency of CHX into HNT was of 8.15 %. All test groups showed controlled and cumulative CHX release up to 30 or 50 days. Significant antimicrobial activity was verified against both microorganisms (p < 0.001). After the 30-day immersion period, the 10 % HNT/CHX group showed a significant increase in hardness (p < 0.05) and a progressive color change (p < 0.001). At T0, the 5 % and 10 % groups exhibited Ra values similar to the control group (p > 0.05), while at T30, all groups showed similar roughness values (p > 0.05). {Significance.} The modification of a SAR with HNT/CHX provides antimicrobial effect and controlled release of CHX, however, the immediate surface roughness in the 3 % group was compromised when compared to the control group.
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Antiinfecciosos , Nanotubos , Clorhexidina/farmacología , Clorhexidina/química , Resinas Acrílicas/química , Arcilla , Ensayo de Materiales , Propiedades de SuperficieRESUMEN
BACKGROUND: Nanoparticles (NPs) have gained significant attention in various fields due to their unique properties and potential applications. Polymethyl methacrylate (PMMA) is an acrylic resin widely used in dentistry and medicine. However, the effect of different types of NP fillers on the physical properties of PMMA-based resins has not been thoroughly explored in the literature. OBJECTIVES: The present study aimed to evaluate the effects of 3 different types of NP fillers on the physical properties of an experimental PMMA-based resin as a function of the NP content and concentration. MATERIAL AND METHODS: Ten groups (n = 10) were designed. The specimens were composed of an acrylic resin, silicon dioxide (SiO2), cerium dioxide (CeO2), and titanium dioxide (TiO2) at the following ratios (wt%): group 1 (G1) - control; group 2 (G2) - 0.5% SiO2; group 3 (G3) - 1% SiO2; group 4 (G4) - 3% SiO2; group 5 (G5) - 0.5% CeO2; group 6 (G6) - 1% CeO2; group 7 (G7) - 3% CeO2; group 8 (G8) - 0.5% TiO2; group 9 (G9) - 1% TiO2; and group 10 (G10) - 3% TiO2. Transmission electron microscopy (TEM) was used to assess the quality of NP dispersion. Thermal stability was assessed with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effects of the abovementioned NPs on the properties of the resin were evaluated using the Archimedes principle for density, the Vickers hardness (VH) test and the impact strength (IS) test. Data analysis employed the oneand two-way analysis of variance (ANOVA), followed by Duncan's post hoc test at a significance level of 0.05. RESULTS: Transmission electron microscopy showed partial NP dispersion. All types of NPs enhanced the mechanical properties of the acrylic resin except for IS, which was similar to that of the control group. Among the types of NPs, irrespective of the weight percentage, CeO2 showed higher thermal stability and higher IS for 0.5 wt% and 1 wt% as compared to other groups, as well as the highest values of density at 0.5 wt%, 1 wt% and 3 wt%. Titanium oxide at 1 wt% presented a higher VH as compared to other groups. The fracture pattern was the same for all groups. CONCLUSIONS: Incorporating the tested NPs into the acrylic resin resulted in enhanced physical properties, primarily attributed to a lower NP content.
Asunto(s)
Resinas Acrílicas , Nanopartículas , Humanos , Resinas Acrílicas/química , Polimetil Metacrilato , Dióxido de Silicio , Ensayo de Materiales , Propiedades de Superficie , Nanopartículas/químicaRESUMEN
Objetivo: avaliar in vitro o polimento sobre resina acrílica quimicamente ativada (RAQA), por meio da rugosidade de superfície (Ra). Materiais e Método: Foram confeccionadas 40 amostras de RAQA, com dimensões de 10 a 10 x 2 mm, e foram divididas em quatro grupos (n=10): ausência do acabamento (AA); Ausência de polimento (AP); Polimento químico (PQ); Polimento com borrachas siliconadas + Escovas (PM). Os espécimes foram avaliados no quanto a rugosidade média (Ra) antes e após o envelhecimento em água destilada em uma estufa por 60 dias. Três medições de Ra (µm), na horizontal foram realizadas e calculada uma média para cada espécime. Os dados foram analisados de forma descritiva e inferencial, ANOVA de medidas repetidas e teste de Tukey com nível de significância de 5%. Resultados: Inicialmente, o grupo AA teve os menores valores de Ra e o grupo AP os maiores valores de rugosidade, com média e desvio padrão respectivamente 0,17 (±0,11) e 0,52 (±0,10). Após o envelhecimento, o grupo AA teve as menores médias e o grupo PQ os maiores valores de Ra, sendo 0,38 (±0,20) e 1,33 (±0,32), respectivamente. Os resultados evidenciaram diferença estatística significante quando as amostras foram submetidas ao acabamento com brocas. Conclusão: A RAQA necessita de polimento após acabamento com brocas, uma vez que a ausência de polimento comprometerá a lisura de superfície do material.(AU)
Objective: to evaluate in vitro polishing on chemically activated acrylic resin (RAQA), using surface roughness (Ra). Materials and Method: 40 RAQA samples were made, measuring 10 to 10 x 2 mm, and divided into four groups (n=10): absence of finishing (AA); Lack of polishing (AP); Chemical polishing (PQ); Polishing with silicone rubbers + Brushes (PM). The specimens were evaluated for their average roughness (Ra) before and after aging in distilled water in an oven for 60 days. Three horizontal Ra (µm) measurements were taken and an average was calculated for each specimen. Data were analyzed descriptively and inferentially, using repeated measures ANOVA and Tukey test with a significance level of 5%. Results: Initially, the AA group had the lowest Ra values and the AP group the highest roughness values, with mean and standard deviation respectively 0.17 (±0.11) and 0.52 (±0.10). After aging, the AA group had the lowest averages and the PQ group the highest Ra values, being 0.38 (±0.20) and 1.33 (±0.32), respectively. The results showed a statistically significant difference when the samples were finished with drills. Conclusion: RAQA requires polishing after finishing with drills, as the lack of polishing will compromise the surface smoothness of the material.(AU)
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Resinas Acrílicas/química , Pulido Dental/métodos , Valores de Referencia , Elastómeros de Silicona , Propiedades de Superficie , Factores de Tiempo , Análisis de Varianza , Estudio de EvaluaciónRESUMEN
BACKGROUND/AIM: Contamination of ethylene vinyl acetate (EVA) during mouthguard fabrication can cause delamination. The study evaluated the effects of different EVA surface treatments on the contact angle, laminate bond strength, and elongation capacity. MATERIALS AND METHODS: Specimens of two bonded EVA plates were prepared (n = 30). The Shore A hardness of standardized EVA plate specimens was measured before and after thermo-plasticization. The EVA plates were randomly allocated to one of five different surface treatment groups: no treatment (control); isopropyl alcohol, 100%; chloroform, 99.8%; self-cure acrylic resin monomer (methacrylate, ethylene glycol dimethacrylate, and chemical initiator-amine type); and ethyl alcohol, 70%. The maximum breaking force and elongation at the site of fracture were recorded using a universal testing machine. The contact angle surface was measured using ImageJ software. Scanning electron microscopy of the EVA surface was performed. The laminate bond strength was obtained by dividing the maximum breaking force by the bonding area between the two EVA plates. The laminate bond strength and maximum elongation data were analyzed by one-way ANOVA, followed by the Tukey's and the Dunnet test. The failure mode data was analyzed using the chi-square test (α = .05). RESULTS: EVA surface treatment significantly influenced the laminate bond strength and maximum elongation (p < .001). The control group had a higher contact angle and significantly lower laminate bond strength and maximum elongation than the other groups (p < .001). The acrylic resin monomer and chloroform-treated specimens had similar laminate bond strength and maximum elongation. The acrylic resin monomer group had a significantly lower contact angle (p < .001). CONCLUSIONS: All treatments had a significantly higher laminate bond strength and maximum elongation than the control group. The acrylic resin monomer and chloroform groups had a significantly higher laminate bond strength and maximum elongation and the acrylic resin monomer group had a lower contact angle than the other groups. The chloroform should be avoided due its hazardous effects.
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Recubrimiento Dental Adhesivo , Propiedades de Superficie , Cloroformo , Resinas Acrílicas/química , Etilenos , Ensayo de Materiales , Análisis del Estrés DentalRESUMEN
"Smart" nanogels are an attractive tool for the development of new strategies of immunization in veterinary medicine. Here, we reported the synthesis and physicochemical characterization of thermoresponsive nanogels based on poly(N-isopropylacrylamide) (pNIPAM) and theirin vitro, ex vivoand in vivo (mice model) performance. Smart nanogels of ca. 250 nm, with a transition temperature of 32 °C were obtained by precipitation polymerization. Assays to evaluatepNIPAM nanogels cytotoxicity were performed in different cell lines showing high biocompatibility (>70 %). The efficient internalization of the system was studied by confocal microscopy as well as flow cytometry. The ability to protect and deliver antigens was analyzed using the outer membrane lipoprotein A (OmlA), an important virulence factor ofActinobacillus pleuropneumoniae(App)cause of porcine pleuropneumonia. This lipoprotein was synthesized by recombinant technology and its technique was also described. The biodistribution ofpNIPAM nanogels administered intranasally was performedinvivo and ex vivo through Pearl Imaging System, which showed that nanogels were kept mostly in the lungs during the evaluated time. Besides, the efficacy of the proposal nanogel-based vaccine was studiedin vivoby measuring the antibody titers of BALB/c mice inoculated with OmlA encapsulated intopNIPAM nanogels compared to OmlA plus aluminum hydroxide adjuvant. The results proved the ability of nanogels to stimulate a humoral immune response. Therefore, we have demonstrated thatpNIPAM nanogels can be used as an efficient platform for vaccine nanocarriers.
Asunto(s)
Resinas Acrílicas , Vacunas , Ratones , Porcinos , Animales , Nanogeles , Distribución Tisular , Resinas Acrílicas/químicaRESUMEN
BACKGROUND: Polymerization conditions affect the physical-mechanical properties of acrylic resins used for craniofacial prostheses. OBJECTIVE: The aim of this study was to evaluate the effect of microwave polymerization on the thermomechanical properties and surface morphology of ocular prostheses fabricated with polymethyl methacrylate (PMMA). METHODS: PMMA discs were polymerized with microwave energy and with conventional heat polymerization (CHP) method. Ocular prostheses were fabricated to determine whether there were changes according to the polymerization method. The surface morphology and roughness were observed under SEM and AFM. The Vickers Hardness number (VHN) and flexural strength were measured. Thermal properties were evaluated with TGA/DSC, and chemical composition with FTIR. RESULTS: The PMMA acrylic resin polymerized with microwave energy showed a smooth surface with some relief areas. In the internal surface of the ocular prosthesis with microwave energy the PMMA is more compact. The mean roughness values were higher and statistically significant with CHP (P < 0.05), while the surface hardness and flexural strength were higher with microwave energy (P < 0.05). CONCLUSION: There were no changes in the calorimetry with either method, TGA showed an exothermic peak around 120 °C with CHP method. PMMA polymerized with microwave energy improved the mechanical and surface properties of the ocular prostheses.
Asunto(s)
Resinas Acrílicas , Polimetil Metacrilato , Polimetil Metacrilato/química , Polimerizacion , Resinas Acrílicas/química , Microondas , Ensayo de Materiales , Propiedades de Superficie , Dureza , Bases para DentaduraRESUMEN
This in-situ study aimed to evaluate the chromatic stability, microhardness, and surfacefree energy of chemically activated acrylic resin (CAAR) samples. Eighty CAAR samples were made and each volunteer (n = 20) received two palatal plates with two sides of groups (without and with glaze application). The samples were exposed to two conditions: the control condition (sucrose 30%) and the test condition (sucrose 30% and 0.12% chlorhexidine). The volunteers used the first palatal device (control condition) for seven days and the second palatal device (test condition) for another seven days, with a seven-day break between them. Then, the ΔΕ00, microhardness, and surface-free energy tests were performed. Analysis of Variance and the Tukey test were used (α = 0.05). The control group with glaze showed higher ΔΕ00 compared to the group without the glaze. The test group with glaze had less ΔΕ00 than their respective controls. In both periods, when the glaze was applied, higher microhardness values were found for all groups. Groups with glaze showed lower roughness and higher surface-free energy than groups without the glaze. The values obtained in this study were satisfactory, showing the clinical efficacy of glaze and the use of 0.12% CH for maintaining the physical and mechanical properties of CAAR.
Asunto(s)
Resinas Acrílicas , Clorhexidina , Humanos , Resinas Acrílicas/química , Curación por Luz de Adhesivos Dentales , Luces de Curación Dental , Propiedades de Superficie , Ensayo de Materiales , DurezaRESUMEN
Aim: To assess the effect of different mechanical surface treatments on flexural strength of repaired denture base. Material and Methods: Sixty bar-shaped specimens of heat-polymerized acrylic resin were fabricated, and divided into six groups (n=10). All specimens, except the positive control group (group PC), were sectioned into halves to create a 1-mm clearance. A negative control group with no surface treatment (group NC) was also considered. Other groups underwent different surface treatments: group Laser; treated with erbium: yttrium-aluminum-garnet (Er:YAG) laser, group APA; airborne-particle abrasion (APA), group APA plus Laser; a combination of laser and APA, and group Bur; bur grinding. After measuring surface roughness (Ra) with a profilometer, all sectioned specimens were repaired by auto-polymerizing acrylic resin, and thermocycled afterward. Three-point bending test was performed by a universal testing machine. Data were statistically analyzed (α=0.05). Results: The mean surface roughness of all experimental groups were significantly higher than that of group NC (p<0.05). The mean flexural strength of all groups was significantly lower than that of group PC (p<0.05). Group B had significantly higher flexural strength than the other surface-treated groups (p<0.05). Group Laser had significantly higher flexural strength than groups APA (p=0.043) and APA plus Laser (p=0.023). No significant difference was found between groups APA and APA plus Laser (p=0.684). Conclusion: All surface treatments increased the surface roughness and flexural strength compared with the untreated group. The highest flexural strength was observed in specimens treated by bur grinding and then laser, however, it was still significantly lower than intact specimens.
Objetivo: Evaluar el efecto de diferentes tratamientos superficiales mecánicos sobre la resistencia a la flexión de la base de la prótesis reparada. Material y Métodos: Se fabricaron sesenta especímenes en forma de barra de resina acrílica termo-polimerizada y se dividieron en seis grupos (n=10). Todas las muestras, excepto el grupo de control positivo (grupo PC), se seccionaron en mitades para crear un espacio libre de 1 mm. También se consideró un grupo de control negativo sin tratamiento superficial (grupo NC). Otros grupos se sometieron a diferentes tratamientos superficiales: grupo Láser; tratados con láser de erbio: itrio-aluminio-granate (Er:YAG), grupo APA; abrasión por partículas en el aire (APA), grupo APA más láser; una combinación de láser y APA, y grupo Bur; molienda de fresas. Después de medir la rugosidad de la superficie (Ra) con un perfilómetro, todas las muestras seccionadas se repararon con resina acrílica de autopolimerización y se sometieron a termociclado. La prueba de flexión de tres puntos se realizó con una máquina de prueba universal. Los datos se analizaron estadísticamente (α=0,05). Resultados: La rugosidad superficial media de todos los grupos experimentales fue significativamente mayor que la del grupo NC (p<0,05). La resistencia media a la flexión de todos los grupos fue significativamente menor que la del grupo PC (p<0,05). El grupo B tenía una resistencia a la flexión significativamente mayor que los otros grupos tratados en la superficie (p<0,05). El grupo Láser tuvo una resistencia a la flexión significativamente mayor que los grupos APA (p=0,043) y APA más Láser (p=0,023). No se encontró diferencia significativa entre los grupos APA y APA más Láser (p=0,684). Conclusión: Todos los tratamientos superficiales aumentan la rugosidad de la superficie y la resistencia a la flexión en comparación con el grupo sin tratar. La resistencia a la flexión más alta se observó en las muestras tratadas con fresado y luego con láser; sin embargo, aún era significativamente más baja que las muestras intactas.
Asunto(s)
Humanos , Resinas Acrílicas/química , Reparación de la Dentadura , Polimetil Metacrilato/química , Materiales Dentales/química , Bases para Dentadura , Láseres de Estado Sólido , Metacrilatos/químicaRESUMEN
A new precursor (Ag+/CS/PNIPA) arranged as a nanogel (nanoreactor) is obtained from the aqueous mixture of Ag+, chitosan (CS) and poly(N-isopropylacrylamide) (PNIPA). A model synthetic system based on the thermally induced aqueous silver ions-CS reaction to form silver nanoparticles (AgNP) is used as a starting point to assess the PNIPA role as a thermo-sensitive additive of synthesis in a low content for the production of size-controlled AgNP. As expected, the PNIPA phase transition produced by the temperature increase leads to chitosan nanogel contraction, lowering the diffusion of ionic species. PNIPA behaves as a successful additive between 5.6 and 10.5 wt% of content blended with chitosan, noticeably improving AgNP nucleation during thermal treatment at 90 °C. Higher PNIPA contents are less effective in achieving size control and broader size distributions are generated. The PNIPA effect on the nanoreactor structure is characterized by rheology, modelled and analyzed against the AgNP morphology obtained.
Asunto(s)
Resinas Acrílicas/química , Quitosano , Nanopartículas del Metal , Quitosano/química , Iones , Nanopartículas del Metal/química , Nanotecnología , Plata/químicaRESUMEN
Glass ionomer cements and resin-based composites are promising materials in restorative dentistry. However, their limited mechanical properties and the risk of bulk/marginal fracture compromise their lifespan. Intensive research has been conducted to understand and develop new materials that can mimic the functional behavior of the oral cavity. Nanotechnological approaches have emerged to treat oral infections and become a part of scaffolds for tissue regeneration. Carbon nanotubes are promising materials to create multifunctional platforms for dental applications. This review provides a comprehensive survey of and information on the status of this state-of-the-art technology and describes the development of glass ionomers reinforced with carbon nanotubes possessing improved mechanical properties. The applications of carbon nanotubes in drug delivery and tissue engineering for healing infections and lesions of the oral cavity are also described. The review concludes with a summary of the current status and presents a vision of future applications of carbon nanotubes in the practice of dentistry.
Asunto(s)
Portadores de Fármacos , Ensayo de Materiales , Nanotubos de Carbono/química , Cementos de Resina , Resinas Acrílicas/química , Resinas Acrílicas/uso terapéutico , Portadores de Fármacos/química , Portadores de Fármacos/uso terapéutico , Humanos , Cementos de Resina/química , Cementos de Resina/uso terapéutico , Dióxido de Silicio/química , Dióxido de Silicio/uso terapéutico , Propiedades de SuperficieRESUMEN
Agricultural production is influenced by the water content in the soil and availability of fertilizers. Thus, superabsorbent hydrogels, based on polyacrylamide, natural cashew tree gum (CG) and potassium hydrogen phosphate (PHP), as fertilizer and water releaser were developed. The structure, morphology, thermal stability and chemical composition of samples of polyacrylamide and cashew tree gum hydrogels with the presence of fertilizer (HCGP) and without fertilizer (HCG) were investigated, using X-ray diffractometry (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA/DTG) and Energy Dispersive Spectroscopy (EDS). Swelling/reswelling tests, textural analysis, effect of pH, release of nutrients and kinetics were determined; the ecotoxicity of the hydrogels was investigated by the Artemia salina test. The results showed that PHP incorporation in the hydrogel favored the crosslinking of chains. This increased the thermal stability in HCGP but decreased the hardness and adhesion properties. The HCGP demonstrated good swelling capacity (~15,000 times) and an excellent potential for reuse after fifty-five consecutive cycles. The swelling was favored in an alkaline pH due to the ionization of hydrophilic groups. The sustained release of phosphorus in HCGP was described by the Korsmeyer-Peppas model, and Fickian diffusion is the main fertilizer release mechanism. Finally, the hydrogels do not demonstrate toxicity, and HCGP has potential for application in agriculture.