If a child's water supply doesn't have enough fluoride, a doctor or dentist can prescribe sodium fluoride drops or tablets. A dentist may apply fluoride directly to the teeth of a person of any age who is prone to tooth decay. Toothpaste containing fluoride is also beneficial. After thoroughly cleaning the area to be sealed, a dentist conditions the enamel and places a liquid plastic in and over the grooves of the teeth. When the liquid hardens, it forms such an effective barrier that any bacteria inside a groove stop producing acid because food can no longer reach them.
Some people have especially active, decay-causing bacteria in their mouth.
A parent may pass these bacteria to a child, presumably by kissing. The bacteria flourish in the child's mouth after the first teeth come in and can then cause cavities. So a tendency toward tooth decay that runs in families doesn't necessarily reflect poor oral hygiene or bad eating habits. For people who are very prone to decay, antibacterial therapy may be needed. The dentist first removes decayed areas and seals all pits and fissures in the teeth.