UB Researcher Says Dental X-Rays Indicate The Risk of Stroke

BUFFALO, N.Y. -- The way Laurie C. Carter, D.D.S., Ph.D., talks about dental X-rays is strikingly similar to how English professors talk about books.

Cavities and gum disease are only the beginning: students learn how to read bone architecture, soft-tissue shadows and air spaces; how to recognize signs of tumor, bone disease and other systemic diseases, and how to structure the process of reading radiographs so they do not miss less-obvious clues.

Outside of her teaching, Carter's research is perhaps the most compelling example of the range of information that can be extracted from a radiograph -- its hidden themes and meanings.

In the corners of a fairly standard dental X-ray called a panoramic radiograph, it is possible to see the carotid arteries, the large vessels on both sides of the neck that supply blood to the brain. In 1981, an oral surgeon named Arthur Friedlander suggested that calcium deposits visible on these radiographs might indicate atherosclerosis -- a leading cause of stroke -- and thereby indicate the degree of the dental patient's susceptibility to stroke. According to Carter, Friedlander's research was not completely persuasive to pathology researchers because it was performed on military veterans and not on a general population.

A study Carter released last July backed up and extended Friedlander's findings using a broad population. It represented a major contribution from UB to the national diagnostic imaging field for maxillofacial radiology.

"Until recent years, nobody was aware that you could see this on dental films," says Carter.

While additional research is still under way, Carter's study may turn out to have widespread effects.

Stroke is the third leading cause of death in the U.S.; at the same time, only 2 percent of stroke victims experience detectable warning signs. If doctors can identify high-risk candidates for stroke using something as relatively common as a panoramic radiograph, thousands of lives might be extended or saved. Panoramic radiographs usually are taken during a patient's first visit to a new dentist.

Thanks to Carter's research, the question is no longer whether susceptibility to stroke is indicated by panoramic radiographs, but to what degree.

"We don't know the specificity and sensitivity yet," says Carter. "Some patients have had some pretty extensive calcifications on the dental film, and then the arteries are only 35 percent or 40 percent blocked. Other patients have had much smaller calcifications, and some of them are the ones who are over 90 percent blocked."

Her current research, Carter explains, is an attempt to determine whether there is enough consistency between the dental film and the amount of blockage to recommend ultrasound for patients with seemingly large calcifications.

Options for people at risk for stroke would include changes in diet, an aspirin-a-day regime, medications or a surgical procedure called an endarterectomy. Carter notes that, as a dental researcher, she recommends that people discuss all medical decisions with a physician before taking action. She also stresses that she would not recommend getting a panoramic radiograph just to check for susceptibility to stroke.

"While radiation exposure from dental films has decreased enormously over the last decade," she notes, "you still want to use selection criteria when you obtain radiographs. There has to be an indication that there is disease before you go and pop off another set of films."

By the same token, says Carter, it is not too early for people who already have had panoramic radiographs to ask their dentists to check for calcification of the carotid artery. While some dentists, she pointed out, already will be aware of her study, others will not.

For her part, Carter continues to make new dentists aware of recent techniques and discoveries in radiology.

"I love what I do," she says. "I think I'm one of the luckiest people around. I love being able to open a world of diagnostic knowledge to a student who looks at a radiograph and doesn't see anything, who says, 'There are all these funny shadows here and I don't know what they mean.' I teach them how to read it so they can go off on their own, and it opens up a lifetime of learning.

"That's what's great about science," she added. "You're always discovering new things that, in many cases, were always there to be seen, but nobody ever had the idea before, or else nobody taught you how to look."

Perhaps it is not surprising that English professors often say the same thing about literature.