To sum up the caries process on both enamel and root surface:
Coronal Caries:Root Surface Caries:
88 vol. % mineral45 vol. % mineral
plaque relatedplaque and recession related
acid dissolves subsurface "white spot"acid dissolves surface subsurface "sticky"
complete dissolution=cavitationcomplete dissolution=surface contour changes
until cavitation occurs, remineralization is possiblewith collagen in place, remineralization is possible
once collage is destroyed, no framework for remineralization to occur

At every given moment, when the pH drops below the critical threshold for caries, for every tooth surface, no matter the age or location of the surface, it will undergo an acid challenge...a tug of war.

Fluorides become an integral part in the prevention of dental decay for every tooth surface, no matter the age or location...and fluorides play a major role in our practices today.