Problem: Tooth Decay

Also known as dental caries or cavities, tooth decay occurs when plaque, a sticky film of bacteria that forms when you eat sugars or starches, is allowed to linger on teeth for too long.

Who's at Risk: Anyone can get a cavity, but children and older people are the most prone. The incidence among children has been declining, thanks to community water fluoridation and the increased use of fluoride toothpastes, but "more than half of all children have caries by the second grade," according to the U.S. Department of Health and Human Services report Healthy People 2010. Older adults are prone to cavities at the root because protective gum tissue often pulls away.

What to Do: Don't give plaque a chance: Brush with a fluoride toothpaste and floss every day. Children can also benefit from sealants (plastic coatings applied to the chewing surfaces of their back teeth) as soon as their adult molars come in. Older people should be particularly vigilant: "Those who have a tendency toward dry mouth should receive regular fluoride treatments from a dentist and use a fluoride-containing mouth rinse," says Bruce Pihlstrom, D.D.S., acting director of the Center for Clinical Research at the National Institute of Dental and Craniofacial Research (NIDCR).