Navegando por Autor "Henriques, B."
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Artigo Mechanical and thermal properties of hot pressedCoCrMo–porcelain composites developed forprosthetic dentistry(Elsevier, 2014-02) Henriques, B.; Gasik, M.; Souza, J.C.M.; Nascimento, Rubens Maribondo do; Soares, D.; Silva, F.S.In this study, mechanical and thermal properties of CoCrMo–porcelain composites fordental restorations have been evaluated. These metal–ceramic composites were producedby powder metallurgy and hot pressing techniques from the mixtures of metal and ceramicpowders with different volume fractions. Young's moduli and the coefficient of thermalexpansion of materials were evaluated by dynamic mechanical analysis (DMA) anddilatometry (DIL) tests, respectively. The strength inflexion and shear was measured witha universal test machine and hardness with a respective tester. The microstructures andfracture surfaces were inspected by the means of optical microscopy and ScanningElectron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS).Shear strength, Flexural strength and Young' moduli of ceramic and metal-matrixcomposites were found to increase with higher metal particles content. The DMA testsperformed at different frequencies showed no frequency-dependent features of thematerials studied, indicating no viscoelastic behavior. The fracture surfaces analysissuggests the load-transfer mechanism be possibly responsible for this behavior, as thedifferences in CTE are low enough to cause significant thermal stresses in these materials.The results might be included in a materials properties database for further use for designand optimization of dental restorations.Artigo Relation between Dental Implant Joint Surfaces and Biofilm Formation(Dentistry, 2015) Pereira, J.; Tavares, F.P.; Lima, K.C.; Carreiro, A.F.P.; Henriques, B.; Silva, F.S.; Nascimento, Rubens Maribondo do; Lopez-Lopez, J.; Souza, J.C.M.Objective: The main aim of this work was to evaluate the multi-species biofilm formation in vitro on surfaces of dental abutment and implants. Methods: Five commercial implant-abutment assemblies (Titamax CM; Neodent®, Curitiba; Brazil) were assessed in this study. Also, commercially pure (cp) titanium grade IV square samples (10×10×1 mm) were used to prepare surfaces similar to those of titanium implant and abutments (n=10). Titanium square samples and implant-abutmentassemblies were placed into 24 well-plates containing diluted human saliva at 37°C under microaerophilic conditions (5% CO2). After 24, 48, 72 and 96 hours of incubation, biofilms were analyzed by scanning electron microscopy (SEM) and microbiological analyses. Results: The multi-species biofilm formed at retentive areas of commercial abutments and implants like scratches,micro-gaps and defects revealed a high biofilm agglomeration, as shown by SEM analysis. The biofilm density and thecolony-forming unit number were significant higher (p<0.05) on titanium rough surfaces than that of polished titanium surfaces along the growth time. Conclusions: Biofilm analyses revealed a higher biomass density and cell viability on SLA rough surfaces than on polished ones. Abutment and implants revealed the presence of several rough areas promoted by the surface treatment that increase the biofilm accumulation at peri-implant areas.