5 resultados para NIVEL DEL MAR

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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A new species of electric ray of the family Narcinidae, Discopyge castelloi, is described from the southwestern Atlantic off Argentina. Distinctive characters of the new species are the form of the body, the posterior position of pelvic fins and the manner as pelvic fins join the caudal peduncle, the morphology of the nasal curtain and the presence of small but apparently functional eyes. Discopyge castelloi is the fourth torpediniform species reported from the area. It appears to be very rare on the shelf, though the type locality is separated from that of the paratypes by seven latitude degrees. As in the case of Torpedo puelcha, it is probable that the new species has a normal habitat deeper than that of the available specimens.

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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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Dental tooth bleaching is a conservative option for the treatment of tooth stains. It is based on the use of hydrogen peroxide as an active agent. Despite its effectiveness to lighten tooth colour, there is concern regarding its use due to the effects it could have over enamel surface. There is scarce evidence on the subject and contradictions exist between different authors. The aim of this study was to compare enamel surface micromorphology after bleaching teeth with different concentrations of hydrogen peroxide solutions. Method: 50 healthy bovine incisors sectioned horizontally at the cemento-enamel junction were prepared. Contents of pulp chamber and tooth surfaces were cleaned. The buccal surface of each tooth was divided vertically, assigning one half to the control group (CG) and the other randomly to: Group 1: 25 samples treated with 15% hydrogen peroxide with nitrogen doped titanium dioxide. Group 2: 25 samples treated with 35% hydrogen peroxide. Square samples (2x2 mm.) were obtained and observed by SEM (magnification of 5.000x and 10.000x). Results: All treated groups showed longitudinal depressions on the surface and increased surface roughness. Conclusions: Tooth bleaching with hydrogen peroxide produces subclinical alterations over bovine enamel surface. 15% hydrogen peroxide bleaching agent produced less micromorphology alteration over bovine enamel surface than the 35% hydrogen peroxide agent.