Developed by a USC School of Dentistry team led by professor Paul Denny, the test quantifies the genetic component of tooth decay (caries).
Dentists have long known that even in areas with fluoridation and good oral hygiene education, some people just have bad teeth. The USC test spots the risk early, when something can be done about it.
"When we apply this to young children, it allows us to predict what might be their future caries history - the number of cavities that they'll get by, say, their late twenties or early thirties," Denny said.
The Caries Assessment and Risk Evaluation (CARE) test measures the relative proportions in saliva of different types of sugar chains, known as oligosaccharides. The same sugar chains are present on tooth surfaces.
The effect of sugar chains on the tooth's ability to resist disease is analogous to the effect of "good" and "bad" cholesterol on blood vessels. "Good" sugar chains tend to repel the bacteria that cause cavities, while "bad" sugar chains allow the bacteria to bond to a tooth and start the decay process.
Unlike cholesterol, humans' sugar chain makeup is 100 percent genetically determined and cannot be changed. The USC researchers found that the sugar chain makeup in saliva can predict a child's future cavity history to plus or minus one cavity with greater than 98 percent confidence.
Children at the far ends of the spectrum - those with exceptionally weak or strong oral hygiene and nutritional habits - may develop more or fewer cavities than the test predicts. Bad habits may cause tooth decay, but researchers caution against extreme measures: completely eliminating sugar has not been shown to prevent cavities, and over-brushing can cause enamel erosion.
Contact: Carl Marziali
University of Southern California