How transition of fluorine from orally applied sealant into dental matrix occurs and inhibits caries remains unknown. In the current study, we investigated mechanism of caries protection evaluating movement of fluoride ions from sustained-releasing fluoride sealant by EPMA from a crystallographic point and also from inorganic chemical view. Furthermore, we also evaluated differences of 2 kinds of sealant as a fluoride source, which have different releasing mechanism. Our results demonstrated

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... t fluoride ion released from sealant abundantly accumulated in porous structure of tooth. From this result, it was considered that fluoride ion contributed to caries inhibition by infiltrating into porous structure appeared due to decalcification and enhancing pH environment. This result suggests thinking morphological viewpoint upon efficiency of fluorine in clinical dentistry for caries. When 2 different sealant materials were compared, GI-based sealant significantly released more fluoride ion than resin-based fluorine. Moreover GI-based sealant fluoride ion infiltrated significantly much more into decalcified area than resinbased fluorine. Thus in clinical dentistry, selection of GI-based fluoride ion at early periods and then alternation to long-term keeping resin-based fluorine should be considered to treat caries in a better way.