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Module 1: Tooth Decay

1.1 What is Tooth Decay?

Tooth decay is an active process of tooth destruction resulting from interactions between teeth, food, and bacteria.

Bacteria, transmitted via saliva, adhere to tooth surfaces in a sticky film, called dental plaque. When foods containing carbohydrates are consumed, bacteria are able to break down carbohydrates in the mouth, producing acids that attack the enamel of the teeth and that cause mineral loss from teeth. Each time such foods are consumed, the acids attack the enamel of the teeth. After repeated acid attacks, tooth decay may occur, and the acids may create a cavity in the tooth. Cavities occur when the attack is prolonged and exceeds an individual’s resistance and the ability of the teeth to heal. Resistance and healing ability are determined partly by an individual’s physiology and partly by health behaviors.

At first, while the decay is limited to the subsurface of the enamel, the tooth can restore itself. But if the decay progresses and the tooth is not restored, the cavity continues to grow, extending deeper into the hard structures of the tooth and finally into the living pulp tissues within the tooth. The bacterial infection can then spread through the pulp tissue and blood vessels to other parts of the face and body.

What is Tooth Decay?

Note: What is Tooth Decay? is an animinated video with no audio.


Data from the third National Health and Nutrition Examination Survey indicate that 8 percent of 2-year-olds had at least one decayed or filled tooth and that 40 percent of children were affected by age 5.