Effects of fluoride and/or trace elements on enamel solubility.

Various studies have shown that the solubility of dental enamel can be reduced by exposing it to metal ions in the presence of fluoride. The purpose of this study was to determine the effects of various trace metal ions at two concentrations on dental enamel solubility and fluoride uptake. The solubilities of the enamel surfaces and their fluoride concentrations were first determined. Atypical teeth were discarded. Blocks of enamel were then divided into groups of five and solutions of salts of aluminium, strontium, titanium, molybdenum and vanadium followed by fluoride (4,000 ppm) were applied. Two successive layers were then etched off, using perchloric acid. Fluoride in the enamel was determined using an ion-specific electrode system. Calcium was determined by atomic absorption spectrophotometry. The values obtained were used to calculate the thicknesses of the layers removed. The results showed that combined application of aluminium and fluoride led to a marked reduction in solubility of enamel (p less than 0.001). Application of strontium (0.01 M) and fluoride also led to a significant reduction in enamel solubility (p less than 0.01). Pretreatment with titanium solution (both concentrations), aluminium or molybdenum solutions (higher concentrations) increased fluoride uptake in comparison with the control group. Statistically significant increase in fluoride uptake was seen only in those enamels treated with titanium solution at higher concentration when compared with those treated with fluoride alone.