EVALUATION OF SODIUM FLUORESCEIN FOR QUANTITATIVE DIAGNOSIS OF ROOT CARIES

The diagnosis of root caries, in particular the judgment of the activi ty of a visually observed lesion, is difficult. Quantitative determina tion of lesion severity would allow the lesion to be monitored with ti me, so that an indication of lesion activity could be obtained. This p aper describes a step in the development of a method that provides suc h a quantitative determination. Specifically, fluorescein sodium salt is used as a penetrating dye, the subject of study being the relations hip between dye concentration and porosity in demineralized root denti n. Fourteen human third molars were demineralized in vitro (lactic aci d CMC-gel, pH 5; in each of 6 groups for 4, 7, 11, 14, 18, and 21 days ). Fluorescein sodium salt (0.2 g/L) was applied for 2 min. Thin slice s (+/- 130 mu m) were cut from the root surfaces without water cooling . The dye fluorescence radiance in the demineralized dentin was determ ined by means of a micro-Raman spectroscope and compared with the mine ral loss profiles measured with transverse microradiography (TMR). The TMR data were corrected for the difference in measurement area betwee n the two measurement systems. Corrected TMR profiles were compared wi th the corresponding fluorescence scans, showing linear correspondence . The correlation coefficient was r = 0.96. We conclude that, after up take of fluorescein sodium salt for 2 min, the dye concentration in an artificially produced root-surface caries lesion is proportional to t he amount of mineral lost from that lesion.