WASHINGTON — A test may soon be able to determine which patients, whether children or adults, are at greatest risk for dental caries, Paul C. Denny, Ph.D., said at the annual meeting of the American Association for the Advancement of Science.
Caries are the result of infectious disease, and if they remain untreated—in children or adults—they can cause abscesses outside the tooth, affect developing teeth in children, and even affect facial structures such as the jaw, said Dr. Denny of the University of Southern California.
The infectious agents are acid-producing bacteria that live in the mouth. These bacteria “have receptors on their cell walls that attach to specific sugars on chains of glycoproteins that are found in your saliva,” he said.
These glycoproteins form a coating on the teeth called the pellicle. The bacteria use proteins called lectins to bind to these glycoproteins and then produce acid on the surface of the teeth.
The glycoproteins of the pellicle play a very important role by lubricating the tooth surface. The composition of these sugar chains is genetically determined and varies from individual to individual, said Dr. Denny.
What if some people make sugar chains that facilitate bacterial attachment, and other people do not? The test Dr. Denny and his colleagues have developed uses a small amount of saliva and lectins attached to color-producing enzymes to produce a visible reaction between a specific lectin and its partner glycoprotein. He has formed a company to commercialize the test.
“We do find that some of these sugar types are strongly positively correlated with the number of caries in their mouth, but we also find that some of these chains are negatively correlated with the number of cavities, and it's the relative proportions of these positive and negatively correlated chains that give rise to the great range of [cavities] that one sees within a group of people.”
Many of same sugars incorporated into the pellicle also are used to determine blood type. For instance, people with type B blood have galactose as part of the glycoproteins in both their pellicle and saliva.
The researchers tested for eight glycoproteins in 21 different people. After analyzing the data, they created a plot showing that caries risk can be predicted with glycoprotein testing alone.
For instance, the group of people who never had cavities had common glycoproteins (risk level 1), but those who had numerous cavities throughout their mouths had a significantly different combination of glycoproteins (risk level 4).
Between the two extremes, combinations of glycoproteins accounted for those with cavities in their molars (risk level 2), and those with more cavities in both their molars and premolars (risk level 3). Thus, with testing of a person's glycoproteins, his or her level of risk for dental caries can be assessed.
“And if you apply this to children before they have caries, you have the prescription or treatment plan for prevention,” says Dr. Denny. “You could have children grow up caries-free regardless of their risk level.”
Dr. Denny showed the results from children's saliva, which suggested that even though they do not have any caries yet, by their late 20s, they can expect to have 3–8 cavities unless there is intervention such as fluoride treatments, better oral hygiene, and more frequent dental checkups.