Aciduric Resistance of Lanthanum-Treated Teeth

Abstract

As reported previously, non-carious extracted human teeth were treated with 0.1-8.0% lanthanum nitrate solution (La solution), so that Ca²⁺ was displaced by La³⁺ in the enamel surface, and the enamel surface was coated with lanthanum phosphate compounds. The lanthanum phosphate compounds were stable to an acid.
The purpose of this study was to examine the aciduric resistance of the lanthanum phosphate compounds coating the enamel surface.
These teeth were treated with 1, 2, 4, and 8 % La solution for 1-5 weeks, and at regular intervals, the intake of La into the enamel surface was analyzed by electron probe X-ray microanalyzer (X.M.A.). After that the teeth were dipped in 0.1 M acetate buffer (pH 4.0) for 24 hours.
The quantity of La in the enamel surface treated with 2, 4, and 8 % La solution for 1-5 weeks was not very much changed, and Ca and P were little dissolved in acetate buffer. But the enamel surface which was treated with 1 % La solution for 1 week did not include La, and Ca and P were more dissolved in acetate buffer. However, enamel which was treated for 5 weeks included considerable amount of La, and Ca and P were less dissolved.
From this study, we observed that lanthanum strengthens the aciduric resistance of teeth.