Changes in the nature and composition of enamel mineral during procine amelogenesis |
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Authors: | T Aoba E C Moreno |
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Institution: | (1) Physical Chemistry Department, Forsyth Dental Center, 140 Fenway, 02115 Boston, MA, USA |
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Abstract: | Summary The present study was undertaken to investigate changes in the crystalline structure and composition of procine enamel mineral
during amelogenesis. Special attention was given to the carbonate location in the forming apatite crystal. Enamel samples
were obtained from the outer (young) secretory, inner (old) secretory, maturation, and mature (hard) enamel of the permanent
incisors of slaughtered piglets. The crystalline structure and composition of these enamel samples were studied using Fourier
transform infrared spectroscopy, X-ray diffraction, and chemical analyses. The initial enamel mineral in the outer secretory
enamel was rich in acid phosphate and carbonate. The carbonate was mainly substituted for phosphate groups in the apatite
crystals of the early (outer) secretory enamel. Developmental advancement from the outer secretory to the inner secretory
(as well as early maturation) stages brought about significant changes in crystal parameters, namely, shrinkage and expansion
of thec anda unit cell dimensions, respectively, and the shift of av
3 PO4 band to higher wavenumbers in the FTIR spectrum. X-ray diffraction patterns indicated that mineralization during the tissue
maturation was characterized by a gradual growth of enamel crystals parallel to thea-axis direction. A most prominent finding was that, with developmental advancement, a decrease in CO3 per unit mass of P (or Ca) in the tissue, and a concomitant increase in the CO3 occupying OH sites in the crystalline lattice became apparent. The overall results may reflect (1) changes in the composition
of the medium in which precipitation of enamel carbonatoapatite occurs, (2) initial formation of an acid phosphate such as
octacalcium phosphate-like mineral, or (3) modifications of the precipitating phase induced by changes in the kinetics of
the mineral formation. |
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Keywords: | Amelogenesis Enamel mineral Carbonatoapatite |
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