Measurement of enamel demineralization using microradiography and confocal microscopy - A correlational study

Substantial amounts of tooth minerals are lost during dental caries formation. Transversal microradiography, a well-accepted method used to quantify mineral loss, is a time-consuming technique which requires a thin enamel section (100 mu m) and involves the use of x-rays. In an attempt to solve these difficulties, a procedure has been developed in which a human tooth specimen with demineralized enamel is cut in half(HT), stained with a fluorescent dye (rhodamine B) and analyzed using a laser scanning confocal microscope. A series of three studies was conducted to correlate measurements of enamel demineralization obtained from enamel thin (100 mu m) sections (TS) using transversal microradiography with three parameters (area of the lesion; total and average dye fluorescence intensities) measured on the same TS or on a thicker section (HT) of the same specimen by laser scanning confocal microscopy. Results showed that a 0.1 mM rhodamine B solution provided the most adequate imaging conditions for confocal microscopy. Pearson's correlation coefficients, calculated between microradiography and confocal microscopy data obtained using a 0.1 mM rhodamine B solution, were: Delta Z vs. HT lesion area = 0.95; Delta Z vs. HT total fluorescence = 0.80; Delta Z vs. HT average fluorescence = 0.74; Delta Z vs. TS lesion area = 0.95; Delta Z vs. TS total fluorescence = 0.74; Delta Z vs. TS average fluorescence = 0.55. All these correlations coefficients were statistically significant (p<0.01). It is concluded that in enamel demineralization studies statistically significant correlations exist between parameters measured using transversal microradiography and parameters quantified using confocal microscopy.