Insolubilization of Deciduous Tooth Enamel by the Two-Step Method with Fluoride and Lanthanum Treatment

Abstract

The acid-resistance of the tooth surface is strengthened by the two-step treatment (F-La treatment) with acidulated-phosphate fluoride and lanthanum chloride solutions as previously reported by this author et al. Recently, a study was made to examine some clinical applications of the treatment. The acid-resistance effects and the actual condition of the F-La treatment were investigated on human deciduous enamel. Analysis was made using the electron probe X-ray microanalyzer before and after the acid-solubility test. The results were as follows:
1) As compared with those conditions before treatment, the acid-resistance of deciduous tooth enamel increased over six times after the F-La treatment and over two times after just the F-treatment.
2) It was necessary to treat deciduous tooth enamel with 1 mol/l of phosphoric acid prior to the F-La treatment.
3) A three minute treatment with both F and 1% La sufficed for the F-La treatment.
4) Fluorine and lanthanurn penetrated up to approximately 15μm from the enamel surface with the F-La treatment. Even after the acid solubility test, a sufficient quantity of the stated chemicals remained, thus protecting the tooth substance.
5) The solubility of the deciduous tooth enamel was 34% higher than that of the permanent tooth enamel. After the F-La treatment, however, the former diminished to the level of the permanent tooth. Based on these experimental results, one can reconfirm the fact that the chemical reactivity of the deciduous enamel is higher than that of the permanent enamel.