Sugar plays a harmful role in tooth decay. The bacteria that form together to become plaque use sugar as a form of energy.
The mouth is full of hundreds of bacteria, many of which are beneficial to the oral ecosystem. However, certain harmful oral bacteria actually feed on the sugars you eat to create acids that destroy the tooth enamel, which is the shiny, protective outer layer of the tooth. Cavities are a bacterial infection created by acids, that cause your teeth to experience a hole in them. Without treatment, cavities can progress past the enamel and into the deeper layers of the tooth, causing pain and possible tooth loss.