Ultrastructural and Physicochemical Characterization of a Non-Crosslinked Type 1 Bovine Derived Collagen Membrane.

In this work, in vitro testing was used to study the properties of non-crosslinked type 1 bovine derived collagen membranes used in bone regeneration surgery. Collagen membranes were prepared, their surface roughness was quantified by interferometry, their morphology was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), their wettability was measured by the contact angle technique, their mechanical properties were investigated by tensile testing, their phase transformation temperatures were measured by Differential Scanning Calorimetry (DSC), and their biocompatibility was evaluated by immunological testing. The calorimetry tests showed that the membrane is formed only by type 1 collagen. The SEM observations showed that the morphology consists of layers of highly organized collagen fibers and patterns of striated fibrils typical of type 1 collagen. The small contact angle showed that the membrane is hydrophilic, with the possibility of rapid absorption of body fluids. The tensile tests showed that the membrane has enough elasticity, ductility, and mechanical strength for use in tissue regeneration. With the immunostaining technique, it was possible to confirm the membrane biocompatibility.

Influência do tratamento térmico no limite de escoamento de fios ortodônticos / Influence of heat treatment in the yield limit of orthodontic wires

O ortodontista deseja que durante o tratamento para a correção da arcada dentária os aparelhos exerçam forças rigorosamente controladas sobre os dentes. Para garantir este controle é importante que o aparelho ortodôntico apresente estabilidade térmica e mecânica quando em uso, a qual é conseguida mediante a escolha correta dos materiais e de seu estado termomecânico. Neste trabalho fios de aço inoxidável, usados em Ortodontia, foram adaptados na forma de arcos, tratados termicamente para alívio de tensões e submetidos a ensaios de tração e medidas de largura de linha do espectro de ressonância ferromagnética. Os resultados mostraram que a temperatura de tratamento altera o limite de escoamento dos fios e que existe uma relação entre a resistência mecânica e o tipo e a fração volumétrica das fases presentes