University of Illinois at Chicago: College of Dentistry

Elevated dental plaque acid is a risk factor that contributes to cavities in children. But eating bran flakes with raisins containing no added sugar does not promote more acid in dental plaque than bran flakes alone, according to new research at the University of Illinois at Chicago College of Dentistry.

Some dentists believe sweet, sticky foods such as raisins cause cavities because they are difficult to clear off the tooth surfaces, said Dr. Christine Wu, Professor and Director of Cariology Research at the University of Illinois at Chicago College of Dentistry and lead investigator of the study.

But studies have shown that raisins are rapidly cleared from the surface of the teeth just like apples, bananas, and chocolate, she said.

In the study, published in the journal Pediatric Dentistry, children ages 7 to 11 compared four food groups--raisins, bran flakes, commercially marketed raisin bran cereal, and a mix of bran flakes with raisins lacking any added sugar.

Sucrose, or table sugar, and sorbitol, a sugar substitute often used in diet foods, also were tested as controls.

Children chewed and swallowed the test foods within two minutes. The acid produced by the plaque bacteria on the surface of their teeth was measured at intervals.

All test foods except the sorbitol solution promoted acid production in dental plaque over 30 minutes, with the largest production between ten to 15 minutes.

Dr. Wu said there is a “well-documented” danger zone of dental plaque acidity that puts a tooth’s enamel at risk for mineral loss that may lead to cavities. Dr. Achint Utreja, a research scientist and dentist formerly on Dr. Wu’s team, said plaque acidity did not reach that point after children consumed ten grams of raisins. Adding unsweetened raisins to bran flakes did not increase plaque acid compared to bran flakes alone.

However, eating commercially marketed raisin bran led to significantly more acid in the plaque, he said, reaching into what Dr, Wu identified as the danger zone.

Plaque bacteria on tooth surfaces can ferment various sugars such as glucose, fructose, or sucrose and produce acids that may promote decay.

But sucrose is also used by bacteria to produce sticky sugar polymers that help the bacteria remain on tooth surfaces, Dr. Wu said. Raisins themselves do not contain sucrose.

In a previous study at UIC, researchers identified several natural compounds from raisins that can inhibit the growth of some oral bacteria linked to cavities or gum disease.

The study was funded by the California Raisin Marketing Board and the UIC College of Dentistry.

College of Dentistry: News