Journal of Dental Research, Vol 70, 187-191, Copyright © 1991 by International & American Associations for Dental Research Online Journals
The distribution of magnesium in developing rat incisor dentin
J. Steinfort, F. C. Driessens, H. J. Heijligers and W. Beertsen
Department of Periodontology, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands.
Previous studies have shown that rat incisor dentin contains a considerable
amount of magnesium that is distributed heterogeneously. The
cementum-related dentin, especially its incisal portion, is richest in
magnesium. It was the purpose of the present study to investigate the
changes that occur in the magnesium content during dentin maturation.
Cross-sections were prepared from rat incisors at the apical, middle, and
incisal levels. By means of an electron microprobe, tracings were made of
the Ca-, Mg-, and P- signal frequencies. Comparison of corresponding dentin
layers within and between the cross-sections showed that the Mg/P molar
ratio was always higher in the cementum-related dentin (CRD) than in the
enamel-related dentin (ERD) and increased from the apex toward the incisal
edge. Especially in the incisal cross-section, an increase in Mg/P was
found from the older (peripheral) toward the younger (central) dentin
layers. As the Mg/P ratio varied from 0.07 to 0.33, the Ca/P ratio was
found to fluctuate from 1.48 to 1.15. The two ratios appeared to be highly
correlated (r = -0.97; p less than 0.001), suggesting that Mg replaces Ca
and is bound to phosphate.
