Attack of plaque
Plaque on the surface of the teeth eats away at minerals in enamel, the hard outer coating. Tiny holes open up in the enamel, which are the earliest forms of cavities. This makes it easier for bacteria and acids in plaque to keep moving towards the dentin. Dentin has microscopic tubes in it that connect to the underlying nerves. That’s why tooth sensitivity is often a calling card of this phase of cavity development.