Saliva exhibit teaches a good lick of science

February 05, 2007|By Chris Emery | Chris Emery,sun reporter

Janet Dodd was impressed yesterday with the elegant decor of the National Museum of Dentistry.

Then she found the saliva room.

On a pedestal in the center of the room stood a beaker filled with a murky gel. It was meant to simulate the 600 milliliters of saliva a person produces in a single day - enough to fill a soda bottle from a vending machine.

Dodd winced in disgust at the sight of the beaker's contents. "I have no interest in this," she said, exiting the room quickly.

The display is part of an exhibit titled Saliva: A Remarkable Fluid. It is part of an installment at the Baltimore museum called Your Spitting Image, which explores the connection between human genetics and dentistry.

Another portion of the exhibit focuses on the use of dental records and DNA collected from teeth and saliva to identify the remains of disaster victims and solve crimes. (Licking a postal stamp, for instance, leaves behind enough DNA to identify the licker.)

Scott Swank, the museum's curator and formerly a practicing dentist, said the growing importance of spit in medical diagnostics prompted the saliva display.

Saliva is already being used to test for HIV, he said, and might one day be used to screen for other diseases, drug use and pregnancy.

Saliva-based HIV tests produce results more quickly than blood tests, Swank said, enabling medical personnel to provide guidance to patients more quickly. "With blood tests they would often lose contact with patients," Swank said. "Saliva tests make that less likely."

Researchers are also trying to develop ways to use the fluid to screen for genetic predisposition to certain cancers and other diseases. For example, a clinical trial is now under way for a test that uses DNA from cheek cells found in saliva to predict a woman's lifetime risk for developing breast cancer.

But the museum's exhibit explains that not everybody can produce saliva. In people with Sjogren's syndrome, the immune system attacks the body's moisture-producing glands.

"They have dry eyes, dry mouth, and have difficulty swallowing," said John J. Sauk, a professor at the University of Maryland Dental School. The exhibit includes a video in which a woman with Sjogren's describes chronic dry mouth. "It seems to totally take your whole being over," she says.

Sauk said people who can't produce saliva often rely on artificial saliva to keep their mouths moist. The woman in the video said she found that bits of butter and cream cheese help.

In addition to exploring high-tech uses for spit, Saliva: A Remarkable Fluid lays out the basics.

The fluid, it explains, is produced by glands in three areas of the mouth: inside the cheek near the ears, the floor of the mouth near the curve of the jaw, and under the tongue. It is a mix of water, electrolytes, mucus and enzymes, and serves a variety of functions.

Children produce nearly as much saliva as a fully grown adult, according to the display.

Anna Bundaleska, who visited the museum with Dodd yesterday, said she learned about the importance of saliva while attending dental school in her native Macedonia. She now works as a dental hygienist in Bethesda.

She was surprised that Baltimore has a dentistry museum, much less an exhibit on spit. "I didn't know anything like this existed," she said.

chris.emery@baltsun.com

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