Fig. 2.

Optical microscopic cross-sectional images for advanced caries lesions in the dentin under net magnification of 4.0× [(5×) × (0.8×)] to simulate the two-visit protocol. (a) Cavity preparation using the caries-detecting dye. (b) After the severe caries lesion was removed, as shown in a dotted line in (a), the SDF was applied to the cavity for 1 min (using a micro-brush) and washed for 30 s. The SDF application stains the cavity slightly. This time, a heavy stain was not detectable, because the severe caries lesion had already been removed. (c) The SDF-applied cavity became dark-colored after a week of storage at 100% RH and 36.7 °C to simulate the second visit. This stained tissue was more easily detectable, which prevented the removal of excess tissue.