You need the combination of of a few things.
in your mouth. The better you can control the bacteria count the less likey you are to get decay. 2) carbohydrate. The bacteria use and produce acid as a by-product. Sugar
is worst 3) a susceptible tooth surface. Smooth sufaces and self cleansing areas of the mouth are less prone to cavities...Sealants
can fill in groves and pits 4) time.