This study examined and compared surface of human dentine after acidic etching with hydrogen peroxide, phosphoric acid liquid and gel. Surface demineralization of dentin is necessary for a strong bond of adhesive at dental surface. Split human teeth were used. After application of mentioned substances at dentin level measures of the contact angle and surface morphology were employed. Surface morphology was analyzed with the help of scanning electron microscopy and atomic force microscopy. Liquid phosphoric acid yielded highest demineralization showing better hydrophobicity than the rest, thus having more contact surface. Surface roughness are less evident and formed surface micropores of 4 �m remained open after wash and air dry providing better adhesive canalicular penetration and subsequent bond.
Evolution of hernia surgery has led to polymeric biomaterials for replacement or reinforcement of the abdominal wall. Their selection, according to the structure and porosity of the material, is directly dependent on the surgical procedure used and interaction between material and abdominal viscera. The objective of the paper is to establish a protocol for the selection of hernia mesh fixation materials based on polymer structure related to the surgical procedure used. The biomaterials that promote infection should be avoided and those that do not provide a long-term mesh placement should be used in combination with other devices to compensate for this fault. In conclusion, is much better to adapt the fixation biomaterials used in clinical practice to the specific surgical procedure, given the physical and chemical characteristics of these polymers, in order to reduce the morbidity associated with this type of surgery.
In recent years, researchers have been able to identify new materials with special properties that can be used in major medical fields. Magnesium-based materials used in orthopedics are an important alternative, being the third generation of biocompatible materials. A biodegradable magnesium-based material has the ability to degrade at a certain rate, is biocompatible, and together with other alloying elements ensures osteointegration. Mg-0.5Ca-xY biodegradable alloys will be developed in an induction melting furnace using ceramic crucibles, melting at 710-720 °C in the controlled atmosphere of 5.0 Ar. SEM analyses and X-ray diffraction reveals the size distribution of Mg-sized grains, with a hexagonal lattice and formation of compounds with the two alloying elements: Mg2Ca, Mg2Y, Mg24Y5uniformly arranged in the α-Mg matrix. The alloying elements influence the microstructure, the size of the α-Mg grains decreasing considerably.
Broad introduction and development of polymeric materials in abdominal hernia surgery led to the emergence and identification of secondary complications due to interaction between prosthetic material and human tissue. Whether identification of these reactions has led to the placement instructions of the prostheses into the wall structures of adbomen, there is no clear rule on fixation materials of these prosthesis; they generally follow the recommendations of the prosthesis materials.There are some situations in which the faulty choice of fixing materials can compromise such surgery, followed by chronic septic complications and negative effect on quality of life of these patients and increased risk of recurrence.The choice of fixing materials considering the structural characteristics of polymeric threads can prevent chronic suppuration secondary to this type of surgery.
Biodegradable materials are a further development of new medical applications, such as orthopedic implants and vascular stents, or the tissue scaffold. The variety of alloying elements introduced into magnesium alloys lead to superior corrosion resistance and mechanical properties similar to the biological bone. From a mechanical point of view, increasing the percentage of calcium leads to decreased strength and elongation resistance, and Yttrium addition greatly improves tensile strength and favors a slower degradation process. Three different Mg-0.5Ca-xY alloys were obtained, varying the concentration of the Y-element. The Mg-0.5Ca-xY system was tested from the point of view of micro-scratch and micro-indentation with three determinations each, obtaining results for Young's mode, micro-hardness, COF and stiffness. These alloys possess mechanical properties for use as orthopaedic applications. As future studies, mechanical properties can be improved by performing heat treatments.
The aim of this research was to determine the influence of the metallic materials characteristics on the dynamics of a car crash. Another important aspect is that the metallic parts are sometimes repaired after minor accidents and this fact influence strongly the mechanical characteristics and their influence on the dynamics of a car crash. In this paper, we analyze the mechanical characteristics of thin steel plates repaired by local heating associated with plastic deformation (similar to hot working) and cold straightening (similar to local cold working) for automotive side and door panels made of structural steel. Thin sheet plates, 0.9mm thickness, were deformed by impact and repaired by local heating using the flame and induction heating then plastically deformed while hot as well as straightened without heating. The heat repaired samples were studied by light microscopy to determine microstructure change and samples were tensile tested to determine their mechanical characteristics. Local excessive grain growth generates anisotropy, the assembly behaves as a composite material with regions that show significant plastic deformations while others little or no deformations at all. Without procedures adjusted to each material repairs involving heating are to be avoided, cold working should be employed when replacement is not possible.
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