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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