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The aim of this article is to present the decalcification process dynamic …

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- Decalcification Dynamic of Dog Mineralized Tissue by Microwaves

The decalcified methods, independently of the demineralized agent used, have in common the fact that are accelerated when the solution is shaken, mechanically or electrolitically. Goncalves & Oliverio used an electric decalcification technique, with alternant chain, increasing the decalcification velocity, according to these authors, this process promotes a molecule shaking, resulting an increasing of the decalcification process. The results of this work, using a molecular shaking induced by microwaves, it was observed a similar effect.

Clearly, in 1978, explained that the acceleration process promoted by microwaves is due to the energetic portion of the electromagnetic spectrum that interacts with dipolar molecules provoking a fast oscillation, in this way, increasing the intra and intermolecular movements of the water and of the polar portion of the protein chain, increasing the temperature and resulting in its coagulation. It was observed that, independently of the demineralized agent used, the microwaves accelerated the process and the morphology was preserved. Some authors suggested that the microwaves can induce an elevation of the temperature, increasing the decalcification process by decalcified agent diffusion (Boon & Kok, 1998; Balatona & Loget, 1989;Vongsavane?a et al., 1990; Tornero et al. 1991). As the same time, an increase of the temperature is interesting, but a higher temperature elevation (55 °C and 60 °C) is a disaster for the morphologic characteristics preservation (Balatona & Loget; Boon & Kok; Tornero et al.).

The calcium lost occurred fastly followed by swell and hydrolysis of the calcified matrix (Lillie et al; Wagenaar et al., 1993). Low et al., 1994, observed that the decalcification process at 55 °C will result in cellular destruction. Aiming to solve this problem it was used ice baths, slowing the temperature, which is maintained around to 38 °C. The spatial distribution of the electromagnetic field and the microwave energy in the oven are not uniform, resulting in hot and cold regions (Login & Dvorak, 1990,1994). Some indirect methods have been used to evaluate the electromagnetic field (Boon & Kok; Login & Dvorak, 1990). It was used, in this study, Agar + Giemsa pigment as it was proposed by Login & Dvorak (1994), a simple and efficient method that permits to detect the region with high intensity of electromagnetic field.

The movement of the samples can affect the standardization and calibration of the microwave oven, thus the rotative plate of this microwave oven was turned off. The results of this research are comparable with other studies that evaluated the microwave use in decalcification process (Balatona & Loget; Vongsavan et al. ; Rode et al., 1996). In all of these cited works, the microwave accelerated the tissue decalcification, but in none of them, it was quantified the discharged calcium.

In this research, the analyses of calcium dose showed that, the period of time between the first 6 hours until the second day of irradiation occurred the highest concentration of discharged calcium.This discharged calcium increased during the first six hours, which corresponds to enamel decalcification, otherwise, the discharged calcium at the second day, corresponds to the mandibular bone decalcification, which was slower than the first process. The sample maintained only in solution immersion presented an increasing of the discharged calcium corresponded to the enamel decalcification, only at thirty five day.

Under light microscopy study it was not possible to detect morphological alterations produced during the decalcification process, when it was compared a strong acid, like nitric acid to chelation agent, like EDTA. It is possible that exists an ultrastructurally differences between these two decalcified agents, independently of the decalcification speed.

Thus, it is possible to conclude that if we follow some parameters, like good tissue fixation, microwave oven standardization and temperature decrease, with ice baths, we will achieve a morphologic preservation of the mineralized tissues, independently of the decalcified agent used.


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