Teeth are covered in a hard, outer coating called enamel. Every day, a thin film of bacteria called dental plaque builds up on your teeth. The bacteria in plaque produce acids that can harm enamel and cause cavities. Brushing and flossing your teeth can prevent decay, but once a cavity forms, to avoid further damage, a dentist must fix it with a filling.
Use fluoride toothpaste to protect your teeth from decay. If you are at a higher risk for tooth decay (for example, if you have a dry mouth because of a condition you have or medicines you take), you might need more fluoride. Your dentist or dental hygienist may give you a fluoride treatment during an office visit or may tell you to use a fluoride gel or mouth rinse at home.