111 resultados para Cylinders.


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The species identification is usually an obstacle for conservation studies and management. Sapindaceae species are particularly difficult to identify partially due to inconsistent fruit production which is an important feature in defining genera and species. Because of this difficulty of finding fertile material at particular times of the year, the main focus of this study was to identify species of Sapindaceae in northwestern São Paulo and to produce an identification key based on vegetative morphology such as the form and number of leaflets, the number of vascular cylinders in branches to the species of liana, the presence or absence of domatia, and type of indumentum, among others. In this study, researchers identified species of Sapindaceae present in 18 fragments of native vegetation in the region that includes the Turvo Grande, São José dos Dourados, parts of the Low Pardo, Low Tietê and Tietê-Batalha Hydric Resources Management Unit (UGHRIs). An identification key was developed based on herbarium materials and contained 23 species distributed in 11 genera.

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The aims of this study were to evaluate the effect of root canal filling techniques on root fracture resistance and to analyze, by finite element analysis (FEA), the expansion of the endodontic sealer in two different root canal techniques. Thirty single-rooted human teeth were instrumented with rotary files to a standardized working length of 14 mm. The specimens were embedded in acrylic resin using plastic cylinders as molds, and allocated into 3 groups (n=10): G(lateral) - lateral condensation; G(single-cone) - single cone; G(tagger) - Tagger's hybrid technique. The root canals were prepared to a length of 11 mm with the #3 preparation bur of a tapered glass fiber-reinforced composite post system. All roots received glass fiber posts, which were adhesively cemented and a composite resin core was built. All groups were subjected to a fracture strength test (1 mm/min, 45°). Data were analyzed statistically by one-way ANOVA with a significance level of 5%. FEA was performed using two models: one simulated lateral condensation and Tagger's hybrid technique, and the other one simulated the single-cone technique. The second model was designed with an amount of gutta-percha two times smaller and a sealer layer two times thicker than the first model. The results were analyzed using von Mises stress criteria. One-way ANOVA indicated that the root canal filling technique affected the fracture strength (p=0.004). The G(lateral) and G(tagger) produced similar fracture strength values, while G(single-cone) showed the lowest values. The FEA showed that the single-cone model generated higher stress in the root canal walls. Sealer thickness seems to influence the fracture strength of restored endodontically treated teeth.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Odontologia Restauradora - ICT

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Pós-graduação em Biotecnologia Animal - FMVZ