In the late 1940s, tooth decay was rampant and many Americans expected to be toothless by the age of 45. To address the nation's dental problems, Congress created the National Institute of Dental Research (NIDR) in 1948 as part of the National Institutes of Health in Bethesda, Maryland.

In the early years, research there and elsewhere focused on the causes and prevention of tooth decay and gum disease. In time, the oral cavity and surrounding structures were found to be far more complex and intimately connected with the rest of the body than anyone had imagined. Today NIDR scientists study many disorders affecting oral and craniofacial tissues-AIDS, birth defects, oral cancer, bone and joint diseases, auto-immune disorders, chronic pain, and disorders of taste and smell.

The National Institute of Dental Research's landmark studies of the preventive effects of fluoride on tooth decay led communities around the country to add fluoride to public water supplies. Consumers in turn sought products such as toothpaste, mouthwash, vitamins, and other products that contained fluoride.

Because people have fewer cavities today than 50 years ago, manufacturers now emphasize the cosmetic whitening aspect of oral hygiene products rather than their fluoride content.

With healthier teeth and gums, people are retaining their teeth longer. Healthier teeth in combination with new designs in orthodontic appliances have resluted in a wide market in braces for people of all age groups.

To scientists who study it, saliva is a wonder fluid. It contains molecules that lubricate the mouth and aid digestion, repair early tooth decay, and fight infection. Recently scientists discovered a salivary protein called secretory leukocyte protease inhibitor (SLPI, pronounced "slippy" ) that fights infection by the AIDS virus. They are exploring the use of gene therapy to reprogram salivary glands to make proteins that can treat and prevent various oral and systemic diseases.

In the 1950s scientist discovered that periodontal disease is a bacterial infection. In 1997 a test was developed which uses a drop of blood to predict the genetic likelihood of severe gum disease. Researchers are also studying the possilbility that the bacteria that cause gum disease may circulate into other parts of the body and contribute to coronary artery disease (heart disease) and premature births.