2008, Number 2
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ABSTRACTThe environmental scanning electron microscope (ESEM) has been recently applied to orthopedics, for which a study was performed on the modes of operation of this electron microscope. Optimal conditions were determined to obtain the best topographic image and to perform chemical analysis by X-ray dispersion during the process of bone consolidation. Fifteen male Wistar rats were used, grouped in three per each experimental day. Tibial fracture was provoked and a Kirschner wire was positioned. Rats were euthanized 0 (control), 7, 14, 21 and 28 days after surgery. According to the results, the best bone image was observed with retrodispersed electrons under high vacuum. In the chemical element determination lower variation coeffi cients were obtained under low vacuum for carbon and calcium; for phosphorus, under high vacuum, and in environmental mode, for magnesium, sodium, potassium and iron. In the process of bone consolidation, calcium levels in cortical bone diminished compared to controls, while the calcifi ed bone callus was observed until day 14. Phosphorus concentration increased with time, in both cortical bone and bone callus. Magnesium presented a peak on day 14, and decreased drastically until day 28. Sodium rose continuously until day 28. The study of the chemical composition of bone by the ESEM is optimal in the environmental mode, since values of the elements present in lesser concentrations (1%) showed a lower variation coeffi cient. In bone consolidation process, calcium and phosphorus levels were found at a ratio of 2:1.
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