Why does sugar affect teeth?

Answer

Bacteria in your mouth convert sugar to acid. This acid erodes the enamel, eventually leading to a cavity that will need to be treated by a dentist. If left long enough, dental decay (cavity) can reach the nerve of the tooth and this will require either root canal therapy or removal of the tooth.  

Answer

Like ants at a picnic, bacteria go crazy over the sugar on your teeth, breaking it down into acids that eat away tooth enamel, causing holes called cavities. Plaque also causes gingivitis (say: jin-juh-vi-tis), which is gum disease that can make your gums red, swollen, and sore. Your gums are those soft pink tissues in your mouth that hold your teeth in place.
If you don't take care of your teeth, it won't be long before cavities and unhealthy gums make your mouth very, very sore. Eating meals will be difficult. And you won't feel like smiling so much.

To avoid the damage of your teeth,you have to wash your teeth with water or gargling so the candy left in your teeth will be washed out