الفهرس 
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Abstract
Summary
The objective of this study was to evaluate in vitro the effect of a
constant cumulative dose of 60 Gy (20 Gy/day over three days) of gamma
irradiation on the microhardness of enamel and dentin before and after
demineralization and remineralization. The data in this study involved the
measurement of MHV vickers microhardness on both radiated and nonirradiated gamma irradiation at a constant cumulative dose of 60 Gy (20
Gy/day). The study indicated the following points:
(1) The results showed that the mean microhardness values of the nonirradiated enamel samples were decreased from 093932 kgf/mm2 to
55.722 kgf/mm2
after gamma irradiation, i.e. the decrease in the
microhardness is 5.15%.
(2) Also the mean microhardness values of the non-irradiated enamel
samples were significantly decreased after demineralization,
(3) The mean microhardness values of the demineralized non-irradiated
enamel samples were significantly increased after remineralization,
(4) Also the mean microhardness values of gamma- irradiated enamel
were significantly decreased after demineralization, i.e. the decrease was
significant.
(5) The mean microhardness values of demineralized gamma-irradiated
enamel were significantly increased after remineralization,
(6) Meanwhile the mean microhardness values of the non-irradiated
dentin samples were significantly decreased
(7) Also, the results showed that the mean microhardness values of the
non-irradiated dentin samples were significantly decreased after
demineralization, i.e. the decrease in the mean microhardness was nonsignificant.
Summary and Conclusions
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(8) The results showed that the mean microhardness values of the
demineralized non-irradiated dentin samples were non-significantly
increased
(9) The results showed that the mean microhardness values of the
gamma-irradiated dentin samples were non-significant.
(10) The results showed that the mean microhardness values of the
demineralized gamma irradiated dentin samples were non-significant.