Step Four – Rinse and Dry the Tooth Surface

After etching for 20 seconds, the surface needs to be rinsed with water to remove the acid. Suction and air should be used to thoroughly dry the etched tooth surface. Again, it is extremely important to avoid salivary contamination. If the tooth surface is contaminated by saliva, it will be necessary to repeat the etching process (Figures 12 and 13).

Figure 12.
Figure 13.

A properly etched surface will appear chalky (Figure 14).  A microscopic view of an etched tooth surface (Figure 15).

Figure 14. Properly etched surface.
Figure 15. Microscopic view.