Influência da técnica de fabricação e dos materiais sobre o ajuste da interface pilar/implante em infraestruturas implantossuportadas

The aim of this study was to compare the misfit vertical, horizontal and passivity of zirconia and cobalt-chromium frameworks fabricated for CAD / CAM technology and conventional method of casting. Sixteen frameworks in one-piece, were obtained from a metallic matrix containing three Brånemark compatible implants with regular platform (Titamax Cortical Ti, Neodent). Eight frameworks were fabricated by CAD / CAM system (NeoShape, Neodent): four in zirconia (ZirCAD) and four cobalt-chromium (CoCrcad). Eight other frameworks were obtained by conventional casting method: four cobalt-chromium with UCLA abutment premachined Co-Cr (CoCrUCci) and four cobalt-chromium with UCLA abutment castable (CoCrUCc). The fit vertical, horizontal and passivity by one-screw test were measured using scanning electron microscopy with magnification of 250x. Initially evaluated the passivity by one-screw test and subsequently to assess the vertical and horizontal misfit, tightened all the screws with a torque of 20 Ncm. Mean, standard deviation, minimum and maximum values were calculated for each group. Measurements of horizontal misfit were transformed into cumulative frequency for categorization of the variable and the group later comparison groups. To evaluate the existence of quantitative differences between the groups tested for vertical misfit and passivity, we used the Kruskal-Wallis test. The Mann-Whitney test was used to compare group to group statistical differences (p <0.05). Were observed the respective mean and standard deviation for vertical misfit and passivity in micrometers: ZirCAD (5.9 ± 3.6, 107.2 ± 36), CoCrcad (1.2 ± 2.2, 107.5 ± 26 ), CoCrUCci (11.8 ± 9.8, 124.7 ± 74), CoCrUCc (12.9 ± 11.0, 108.8 ± 85). There were statistical differences in measures of vertical misfit (p = 0.000). The Mann-Whitney test revealed statistical differences (p <0.05) between all groups except between CoCrUCci and CoCrUCc (p = 0.619). No statistical difference was observed for the passivity. In relation to the horizontal misfit groups ZirCAD and CoCrcad did not show best values in relation to CoCrUCci and CoCrUCc. Based on the results it can be concluded that frameworks fabricated by CAD / CAM technology had better values of vertical fit than those manufactured by the casting method, nevertheless, the passivity was not influenced by manufacturing technique and material used. The horizontal fit obtained by frameworks manufactured by CAD / CAM was not superior to those manufactured by casting. A lower variability in vertical adjustment and passivity was observed when frameworks were fabricated by CAD / CAM technology

Passividade na interface prótese/pilar intermediário de infraestrutura implantossuportadas confeccionadas pela tecnologia CAD/CAM e método convencional

The objective of this research was to evaluate the passivity and strain induced in infrastructures screwed on abutments, made by CAD/CAM technology, and to compare these samples with parts manufactured by conventional casting. Using CAD/CAM technology, 4 samples were made from zirconia (Zircad) and 4 samples were manufactured from cobaltchrome (CoCrcad). The control groups were 4 specimens of cobalt-chrome, made by onepiece casting (CoCrci), for a total of 12 infrastructures. To evaluate the passivity, the infraestructures were installed on the abutments. One end was tightened and the vertical gap between the infrastructure and the prosthetic abutment was measured with scanning electron microscopy (250×). The mean strain in these infrastructures was analyzed via the photoelasticity test. A significant difference (p = 0.000) in passivity was observed between the control (CoCrci) and sample groups (CoCrcad and CoCrci). CoCrcad exhibited the best value of passivity (48.76 ± 13.45 μm) and CoCrci the worst (187.55 ± 103.63 μm), Zircad presented an intermediate value (103.81 ± 43.15 μm). When compared to the other groups, CoCrci showed the highest mean strain around the implants (17.19 ± 7.22 kPa). It was concluded that the zirconia infrastructure made by CAD / CAM showed a higher vertical marginal misfit than those made in cobalt-chromium alloy with the same methodology, however, the tension generated in the implants was similar. The CAD/CAM technology is more accurate for passivity and mean strain of infrastructure screwed on abutments than conventional manufacturing techniques

Recurso de interface captcha: segurança e usabilidade na distinção entre humano e máquina

Com o intuito de impedir que computadores enviem mensagens automáticas se passando por usuários reais, desenvolvedores tem utilizado o recurso de interface CAPTCHA para distinguir o preenchimento de dados e submissões realizadas por humanos e por máquinas. Este trabalho apresenta as principais modalidades de CAPTCHAs e discute as implicações na usabilidade. Para tanto, foram aplicados questionários e realizados testes de usabilidade em três modalidades de CAPTCHA. Verificou-se que, embora os usuários tenham consciência da importância do uso do CAPTCHA como ferramenta de segurança, percebeu-se que tal recurso compromete a usabilidade, gerando insatisfação e em alguns casos, a desistência da realização da tarefa

Técnicas baseadas em etnografia e prototipagem no Design de interface de aplicativo mobile para gerenciamento acadêmico

Baseado na metodologia de design participativo, este artigo relata o processo de pesquisa e desenvolvimento de uma versão mobile de um sistema já existente para desktop e amplamente utilizado para o compartilhamento de informações acadêmicas em uma universidade federal do Brasil. A pesquisa foi realizada em duas etapas. Na ‘Etapa I’ foram realizados estudos baseados em etnografia envolvendo docentes e discentes: Grupo de Foco, Análise Contextual, Avaliação Heurística Participativa e Avaliação Cooperativa. Por meio dos resultados foi possível identificar funcionalidades e requisitos desejáveis, problemas de usabilidade de uma versão mobile já em processo inicial de desenvolvimento, bem como e elaboração de uma nova interface gráfica. Na ‘Etapa II’ foram avaliados modelos de interação por meio de protótipos especificamente projetados para testes no mecanismo de lançamento de frequência do sistema mobile que, em seguida, foram avaliados através de testes de usabilidade e questionário de satisfação do usuário.

Histometric Analysis of Bone Repair in Bone-Implant Interface Using a Polylactic/Polyglycolic Acid Copolymer Associated With Implants in Rabbit Tibia

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

Etch and rinse versus self-etching adhesives systems: Tridimensional micromechanical analysis of dentin/adhesive interface

The purpose of this study was to evaluate stress distribution in the hybrid layer produced by two adhesive systems using three-dimensional finite element analysis (FEA). Four FEA models (M) were developed: Mc, a representation of a dentin specimen (41 x 41 x 82 mu m) restored with composite resin, exhibiting the adhesive layer, hybrid layer (HL), resin tags, peritubular dentin, and intertubular dentin to simulate the etch-and-rinse adhesive system; Mr, similar to Mc, with lateral branches of the adhesive; Ma, similar to Mc, however without resin tags and obliterated tubule orifice, to simulate the environment for the self-etching adhesive system; Mat, similar to Ma, with tags. A numerical simulation was performed to obtain the maximum principal stress (sigma(max)). The highest sigma(max) in the HL was observed for the etch-and-rinse adhesive system. The lateral branches increased the sigma(max) in the HL. The resin tags had a little influence on stress distribution with the self-etching system. (C) 2012 Elsevier Ltd. All rights reserved.

Long-term nano-mechanical properties of biomodified dentin-resin interface components

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

Measurement of Interfacial Porosity at the Acrylic Resin/Denture Tooth Interface

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

Efficacy of Air-abrasion Technique and Additional Surface Treatment at Titanium/Resin Cement Interface

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