abstract–The degree of demineralization of the enamel surface was evaluated by means of two different methods, namely by the32P uptake method, and by determining the calcium release directly, using atomic absorption spectroscopy. The accuracy of the32P uptake method was assessed. When applied on groups of young and old premolars separately, the32P uptake method proved to give reliable information about differences between the two groups with respect to the degree of demineralization under equal experimental conditions. For comparison the two methods were used simultaneously in 20 separate tests with varying experimental conditions. The comparison of the results obtained by the two methods showed very good correspondenc