Journal of Dental Research, Vol 74, 1770-1774, Copyright © 1995 by International & American Associations for Dental Research Online Journals
Mineral element analysis of carious and sound rat dentin by electron probe microanalyzer combined with back-scattered electron image
L. Tjaderhane, E. L. Hietala and M. Larmas
Institute of Dentistry, University of Oulu, Finland.
We recently demonstrated the advantages of back-scattered electron images
(COMPO) in the visualization of dentinal caries, and the relationship of
the change in the dentin fluorescence pattern in caries lesions. However,
the exact nature of these changes is not known. In this paper, the nature
of the changes in the areas with reduced mineral content in COMPO images
was investigated. We examined the relation of changes in mineral elements
and the appearance of soft carious and sound dentin in COMPO images using a
scanning electron microscope (SEM) equipped with an electron probe
microanalyzer (EPMA). Rat molars with small dentinal caries lesions just
under the DEJ were chosen for the study. The Ca, P, Na, Mg, Zn, F, and
total contents were determined by EPMA from five different dentin sites,
and the Ca/P and Mg/Ca ratios were calculated. Generally, the lowest
contents were found in caries lesions and highest in mantle dentin, with
the exceptions of Mg and Zn. The Ca/P ratio was lowest in mantle dentin and
highest in carious dentin. The results confirm that the change in
fluorescence in the dentinal caries lesion is correlated with the very
initial changes in mineral content, and that EPMA used in combination with
COMPO images is a useful tool for determining small changes in mineral
elements in the carious and adjacent areas of dentin.
