Iron and dental caries.

Studies of human and animal caries, experiments in vitro and laboratory reports initiated the present study of a possible caries preventing effect of iron. The study comprises two sections. (I) Coatings on teeth of hamsters treated with iron salts and films formed on various solutions containing ferrous ions were examined with scanning electron microscopy and x-ray fluorescence analysis. (II) Enamel surface layers, remineralized caries lesions, fluorosed rat bone, coatings on teeth of hamsters treated with iron salts and films formed on solutions containing ferrous ions were examined with transmitting electron microscopy and electron diffraction. Based on the findings the following effects were visualized. When brought into the mouth, even in small amounts, iron ions will be precipitated on the enamel surface as thin acid resistant coatings containing gels and crystals of hydrous iron oxides. In addition, by adsorbing salivary calcium and phosphate ions these iron compounds seem to be able to nucleate the formation of apatites, thus mediating a replacement of minerals, which have been dissolved during the acid phases of the caries process.