Fig. 4
Scanning electron microscopy stereo-images of an originally sound tooth and a tooth originally with ETW. Figures a and b represent stereo-pair images taken from the exact same surface: image “a” was taken before tilting, and image “b” was taken after 15° tilting. Images were taken from the same enamel surface of an originally sound tooth (S) and a tooth that originally presented ETW (E), before (initial) and after (24min) in vitro erosion. The enamel specimens from originally sound teeth initially present clear undulations of the perikymata (Sinitially), which are absent on teeth that originally presented ETW (Einitially). After in vitro erosion, teeth that originally presented ETW (E24min) exhibit the distinct characteristic of etched enamel