Journal of Dental Research, Vol 55, 829-835, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Composition of fluoridated dental enamel studied by x-ray photoelectron spectroscopy (ESCA)
D. M. Hercules and N. L. Craig
A combination of ESCA and argon-ion etching has been shown to be effective
in determining the surface and subsurface composition of dental enamel. The
heavy organic coating on enamel has been investigated. Beneath this
coating, untreated enamel was found to have invariant phosphorus and
calcuim concentrations over the region surface. The surface of enamel
treated with an acid phosphate-fluoride gel was shown to be almost entirely
connected to calcium fluoride. A phosphate species, noncalcium and possibly
a sodium salt, was found to be present in the surface layer. At a depth
lower than about 60 nm, there was a gradual increase in phosphorus
concentration that approached the value for untreated enamel with
increasing depth. The increasing phosphorus and decreasing fluorine
concentrations were primarily caused by the increasing concentration of
unreacted hydroxyapatite. These results have shown that ESCA coupled with
argon-ion etching, can be used effectively to examine the surface and
subsurface composition of dental enamel. The surface sensitivity, ability
to strip thin layers of material, sensitivity to low atomic weight
elements, and ability to differentiate between different oxidation states
makes a combination of these two techniques extremely useful for dental
research.
