A number of acids have been shown to have a peak concentration above which the rate of enamel demineralization diminishes. Citric acid, used to demineralize dentin in periodontal regenerative procedures, is one such acid. The purpose of this study was to ascertain if there were an optimal concentration of ctric acid with which to demineralize dentin. Various concentrations of ctric acid were applied to bovine dentin and then examined with atomic absorption spectophotometry to m easure the amount of calcium dissolved in each concentration. The ppm calcium/% citric acid solution rose from 0.38 ± 0.38 ppm/0% (control) to a peak of 7.54 ± 2.26 ppm/24%, then fell to 2.43 ± 0.59 ppm/80%, suggesting that there may be a peak concentration beyond which effective dentinal demineralization diminishes. The peak solution was pH = 1.42.