Recovery percentage of remineralization according to severity of early caries.

PURPOSE To analyze the cutoff severity of early lesions according to recovery rate after fluoride treatment. METHODS 100 specimens were demineralized over 3 to 40 days. Specimens were immersed in 2% sodium fluoride solution for 4 minutes, and then in artificial saliva for the rest of the total 24 hours. After 10-time repetition of this cycle, the deltaF recovery rates (R(deltaF,) %) were calculated from the deltaF values before (deltaF(base), %) and after (deltaF(tx), %) remineralization using the QLF-D system. For the discrimination of R(deltaF) based on deltaF(base), the sensitivities versus 1-specificities were analyzed in receiver operating characteristic (ROC) curves, the 95% confidence interval (CI) as well as the significance of differences. The histological features of lesions were observed and lesion depths were digitally measured by polarized light microscopy (PLM). A paired t-test was also performed to assess the differences in deltaF and lesion depth before and after applying fluoride. RESULTS For a threshold recovery percentage of 40%, the suggested deltaF(base) cutoff value was -19.15%, whereas for a threshold recovery percentage of 50%, the suggested cutoff value was -14.60% (P < 0.0001). According to the QLF-D system and PLM analysis, recovery percentage was greater for shallower lesions. Based on fluoride treated recovery percentages, the findings suggested that it is possible for early caries lesions to make more than 50% recovery when the deltaF(base) value was greater than -14.60%. Visually and numerically, the relative recovery percentages were highest during the earlier stages of caries.