AFM analysis of bovine enamel surfaces (Figures 1a,c and e: topographic images; Figures 1b,d and f: phase images).The polished enamel surface without salivary contamination reveals the individual hydroxyapatite crystallites (Figures 1a and 1b). After contamination with saliva (Figures 1c and 1d), the individual enamel crystallites are partially masked by the adsorbed proteins, and small dots or clusters of adsorbed proteins are deposited on the surface (phase image, Figure 1d). After the saliva-contaminated enamel surface has been sprayed with water, the individual enamel crystallites become clearly visible again (Figure 1e), and some residual protein dots are detected on the surface (phase image, Figure 1f). (bars = 20 nm).