Absorption of lanthanum by the enamel surface of extracted human teeth

Abstract

Lanthanum inhibits dental caries formation in hamsters infected with Streptococcus mutans, adherence of human oral microbes to the glass surface, and change the microbial flora in the oral cavity of hamsters.
We used non-carious extracted human teeth with the enamel surface polished. After thes teeth were treated in 8% lanthanum nitrate solution, at regular intervals absorption of La by the enamel surface was quantitatively analyzed with an electron probe X-ray microanalyser, taking as an index the quantity of Ca and P in the enamel surface.
Uptake of La was observed 4 hours after the treatment. The Ca of the enamel surface was reduced and La increased. After 3 day the quantity of La reached a state of equilibrium, fluctuating between 50 and 60%, and the movement of P was small.
We observed that La displaces Ca in the enamel surface and that after long treatment thesurface becomes coated with La.