Relationship between enamel solubility and fluoride concentration in the surface enamel

A new method for analyzing the distribution of fluoride in human enamel.

“…Table 4-1 shows the ratio of the calculated amount of each layer to the determined amount and the ratios of its cumulative amount to the determined amount of the non-F-treated group using the method reported by each respective author . The ratios obtained using the method of IIJIMA et al [9,15] were 3.48 to 10.43 , and 1.72 to 3.02 using the method of NAKAGAKI et al [10] in the Ist layer. The calculated values were therefore extremely higher than the determined values as compared with the values obtained using the various methods.…”

“…(2) Methods developed by IIJIMA et al [9,15] and NAKAGAKI et al [10] Using the methods of IIJIMA et al [9,15] and NAKAGAKI et al [10], a regression power curve was drawn concerning the depth from the enamel surface and the fluoride concentration, measured by each method. Then, by definitively integrating the depth of each layer obtained by the present method with the value (x) calculated from the surface layer of the enamel downwards and at different depths was obtained, on the basis of the regression power curve.…”

“…As a result, the existing method makes it difficult to compare the fluoride concentration of one enamel sample with another at the same depth. For that reason, in recent years, a new method [9][10][11][12] has been adopted in which a calibration curve of the depth from the enamel surface layer against its fluoride concentration is drawn on the basis of the data obtained for these parameters and, from this calibration curve, the estimated fluoride concentration at a given depth can be obtained. However, as this calibration curve is an F-gradient curve [13] which shows that the fluoride concentration decreases sharply from the surface layer of the enamel to the deeper layers, it seems that there is some problem about the accuracy with which it can show the corresponding depth of the average fluoride concentration of a sample obtained as a result of decalcification.…”

“…However, as this calibration curve is an F-gradient curve [13] which shows that the fluoride concentration decreases sharply from the surface layer of the enamel to the deeper layers, it seems that there is some problem about the accuracy with which it can show the corresponding depth of the average fluoride concentration of a sample obtained as a result of decalcification. With regard to this problem, NAKAGAKI et al [10] postulate that this fluoride concentration represents that existing at around the medium depth of the decalcified layer, while IIJIMA et al [9,15], KIRKEGAARD [16] and WEFEL et al [17] contend that it is equivalent to the concentration at the deepest portion.…”

“…In the present study, therefore, the authors devised a new method of analysis to determine the fluoride level at a certain depth from the surface layer of the enamel and, at the same time, conducted a comparative analysis of the results obtained by their method and by the methods adopted hitherto by NAKAGAKI et al [10], II-JIMA et al [9,15] and GRON et al [18]. As a result, extremely interesting findings were obtained, which are reported in the present paper.…”