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

Tooth minerals are lost and regained constantly in a normal, human oral environment, Different methods have been developed to measure this gain and loss in enamel minerals; however, these methods deal with different problems, such as being time consuming or involving the use of X-rays, The aim of this study was to determine if remineralization measured in a thin enamel section (TS) by transversal microradiography (MR) can be reliably monitored by measuring lesion parameters (area, total and average dye fluorescence) on the same TS or on half a tooth (HT) with confocal laser scanning microscopy (CLSM), Thirty-six human enamel specimens were demineralized for 96h, and then half of each specimen was covered with an acid-resistant nail varnish. Specimens were divided into three groups (12/group) and subjected for 20 days to a cyclic remineralization regimen with consisted daily of a 4-hour acid challenge, four I-min treatment periods with 0, 250 or 1,100 ppm F dentifrice slurries (1:2; dentifrice:water) and 20 h in pooled, human saliva, at room temperature. Specimens were cut and analyzed by MR, then stained with a fluorescent dye (0.1mM rhodamine B) for 1h and analyzed using CLSM. Both MR and CLSM detected significantly greater remineralization (p<0.05) in the specimens treated with the fluoride-containing dentifrices than in the specimens treated with 0 ppm F. Significant differences were detected between specimens treated witht the fluoride-containing dentifrices by MR and CLSM (HT area and total fluorescence), Statistically significant (p<0.05) Pearson correlation coefficients were calculated between the MR and CLSM data: difference in MR mineral content (Delta M) versus HT lesion area = 0.71; Delta M versus HT total fluorescence = 0.70; Delta M versus HT average fluorescence = 0.61; Delta M versus TS lesion area = 0.88; Delta M versus TS total fluorescence = 0.63, and Delta M versus TS average fluorescence = 0.40. It is concluded that confocal microscopy in either TS or I-IT may provide valid surrogates (area and total fluorescence) for MR measurements in enamel remineralization studies.