991 resultados para aumento em superfície


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Pós-graduação em Odontologia Restauradora - ICT

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Pós-graduação em Engenharia Mecânica - FEG

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The disadvantages generated by the acid etching of the dentin, such as an increase in its permeability, in the surface moisture and in the potential to denature the external dentinal collagen, the formation of a fragility zone and the citotoxicity of the adhesive monomers; which are all aggravated by the depth of the dentin, have stimulated new and different treatment philosophies of the dentin. The purpose of the present study, therefore, was to investigate the effects of three dentin treatments: laser irradiation, acid etching and hypermineralization, in the shear bond strength of the SMP Plus bonding system. Sixty bovine incisors were extracted and randomly selected immediatly alter the animal's death. They were kept frozen (-18°C) for no longer than 14 days. After buccal dentinal surface had been exposed, X-Rays were taken to control the dentin thickness. The specimens were separated into two groups: (1) Control, kept in distilled water at 4ºC; (2) Mineralized, kept in hypermineralized solution at 4°C for 14 days. Each group was divided into three sub-groups according to the type of dentin treatment used: group F - followed the manufacturer instructions (acid-etching + primer + bond), group AL (acid-etching + primer + bond + laser) and group LA (laser + (laser + acid-etching + primer + bond). A composite resin standard cylinder (Z100-3M) was bond to the dentinal surface and the shear bond strength performed on a Universal lnstron machine 4301, with 500 Kg load and at 0,5mm/min. speed. The analysis of variance (ANOVA) determined that the treatments influenced the shear bond strength values (p<0,05) with the following average shearing load at failure: AL (9,96 MPa), F (7,28MPa) e LA (4,87 MPa). The interaction between the two factors analyzed Group (control and mineralized) and treatment (F, AL, LA) also influenced the shear bond strength (p<0,05). The highest values were obtained...

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Pós-graduação em Ciência Animal - FMVA

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Once petroleum is na exhaustible source of energy, alternative fuels are having more prominence. A much discussed option for replacing fossil fuels is the use of biofuels derived from oils or fats, especially biodiesel. The biodiesel preparation is through a reaction named transesterification, a reaction of triglycerides with a short chain alcohol with a catalyst, producing a mixture of fatty acid esters and glycerol. According to ANP (National Petroleum Agency) specifications, biodiesel can have contaminants due to the catalyst or oil used on its synthesis, such as phosphorus, wich can damage the catalytic converter and cause significant increase in the particles emission. This project aims to develop na alternative method using chemically modified electrodes with iron nanoparticles for determination of phosphorus in biodiesel. For the formation of the iron nanoparticles film on the surface of a glassy carbon electrode, was used a iron sulfate solution. The film was formed after 10 successive cycles, with a scanning speed of 50 mV s-1 and a potential range of -0,9 to -1,25 V. To reduce possible oxides on the surface and activate the electrode, it has been subjected to a cathodic polarization with a potential of -1,25 V for 15 minutes in a sodium hydroxide solution. In cyclic voltammograms obtained in the study of the speed of scanning, there is an increase in the intensity of the anodic and cathodic current peaks. The cathodic peak current varied linearly with the square root of scan rate, showing that the electrode is controlled by diffusion. After successive additions of phosphate there is a linear variation in the current peak in the concentration range of 1,0 x 10-7 a 1,0 x 10-6 mol L-1. To determine if the concentration of phosphorus in real sample, the method of adding standard was used by adding aliquots of phosphate ions in the solution containing soy biodiesel extracted with ....

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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In order to evaluate the hygienic-sanitary conditions of lamb carcasses for human consumption, this study aimed at quantifying populations of indicator microorganisms, such as: mesophiles and psychrotrophs, molds and yeasts, Escherichia coli, Staphylococcus spp. and at identifying pathogenic microorganisms (Salmonella sp. and Listeria spp.). The study was conducted in one lamb slaughterhouse located in the State of São Paulo. Swab samples were collected from muscle surface of forequarter and hindquarter regions of 30 half-carcasses after skinning, evisceration and washing processes. Population counts were between the following values in log10: 2,00 ± 0,32 and 2,59 ± 0,76 UFC/cm2 for mesophiles; 1,52 ± 0,98 and 2,35 ± 1,17 UFC/cm2 for psychrotrophs; 0,75 ± 0,87 and 1,23 ± 0,97 UFC/cm2 for molds and yeasts; 0,00 ± 0,00 and 0,31 ± 0,84 NMP/cm2 for Escherichia coli and 1,75 ± 0,71 and 1,95 ± 0,68 UFC/cm2 for Staphylococcus spp. Salmonella sp. and Listeria spp. were not detected from any of the sampled points. These results indicate the necessity to improve the hygienic-sanitary conditions.

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Introduction: Recent studies have evaluated the relationship between the width of keratinized mucosa and peri-implant tissue health. Insufficiently wide keratinized tissue can be increased surgically, for example by free gingival grafting. The presence or reconstruction of keratinized tissue around the implant can facilitate restorative procedures, promote aesthetics and allow the maintenance of an oral hygiene routine without irritation or discomfort to the patient. Objective: To describe a patient who underwent free gingival graft surgery to increase the width of keratinized tissue in the region of previously implants to support a type of prosthetic protocol. Case report: A patient who had received dental implants to support a type of prosthetic protocol presented with inflamed peri-implant mucosa, but with no keratinized tissue. Free gingival tissue was obtained from the palate and grafted into the anterior maxilla. Sixty days after muco-gingival surgery, we observed that the free gingival graft favored peri-implant health and prosthetic casting. Conclusion: The free gingival graft technique is both easy to perform and effective in increasing the width of keratinized mucosa following implantation.

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Multiple gingival recessions may cause mainly dentinary sensibility and aesthetic alterations. The subepithelial graft is a mucogingival technique which can be used to treat multiple gingival recessions. In this case report the Erbium YAG laser was applied to promote radicular surface decontamination, an important step to reach reinsertion of the gingival tissues on exposed radicular surface.

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The aim of this study was to evaluate the influence of implant angulation and abutment type (UCLA and Estheticone) on stress distribution in screw-retained implant-supported prostheses through photoelasticity. Three models were fabricated with photoelastic resin PL-2 (Vishay, Micro-Measurements Group, Inc Raleigh, N.C., USA) containing one external hexagon implant with 3.75x10mm (Master screw, Conexão Sistemas de Prótese Ltda., Arujá, São Paulo) with 0°, 17° and 30° degrees and a screw-retained prostheses with UCLA and Estheticone abutments. The assembly was positioned in a circular polariscope; axial and oblique (45° degrees) loads of 100N were applied in fixed points on the occlusal crown surfaces by a universal testing machine. The stress generated was photographed and analyzed qualitatively with appropriate software (Adobe Photoshop®). The results demonstrated the same number of fringes for both abutment types for each angulation, with fringes increasing in the same way. A higher number of fringes were closer in the oblique loading mode. It was concluded that there was no significant difference in stress distribution in prostheses with UCLA and Estheticone abutments. Higher stress concentrations were observed with increased implant angulation. Stress concentration and intensity were higher in the oblique load than in axial load application.

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Various surface treatments of dental implants have been developed in order to ensure anchorage to bone tissue, optimization of the determinants of electronic structure, crystallinity, composition and properties. Coating techniques have been proposed in order tocreate unionbiochemicalable to accelerate the early stages ofbone tissue, combining the positive properties of titanium and its alloys bioactivity of ceramic materials. This paper discusses protocol for handling the SBF coating of titanium alloys. The apatite phase nucleation occurs by immersing the substrate in synthetic solution simulating blood plasma (Simulated Body Fluid). The protocol allows manipulation of the SBF solution to establish guidelines regarding the usestreamlinedand organized to make practical application.