Fluoride uptake around cavity walls; two-dimensional mapping by electron probe microanalysis.

This study reports fluoride uptake around the cavity wall of teeth by two-dimensional mapping. Fluoride concentration was measured using the wavelength dispersive x-ray analysis (WDX) method. The buccal cavity wall of a human tooth was coated five times with 2% sodium fluoride solution at three-day intervals for 12 days, and then immersed in a normal saline solution at 37 degrees C. After one month, the tooth was bisected longitudinally through the center of the cavity surface perpendicular to the axial wall. On the polished surface of the cut tooth, the fluoride concentration was measured. Fluoride distribution maps around the cavity wall were drawn using a bundle of the observed analytical lines. Fluoride uptake from fluoride-releasing materials (conventional glass-ionomer cement, light-cured glass-ionomer cement, light-cured composite resin, light-cured bonding agent) around the cavity wall was investigated using the same method. The maps showed higher fluoride uptake in dentin than in enamel and a strong location dependence of fluoride uptake in a tooth, especially in the dentin. Fluoride uptake from the resin was greater than that from the cement. It was summarized from these results that a two-dimensional map of fluoride uptake can provide valuable information on the cariostatic properties of fluoride-releasing materials.