Elevated dental plaque acid is a risk factor that contributes to dental caries 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 (UIC). Some dentists believe sweet, sticky foods such as raisins cause caries because they are difficult to clear off the tooth surfaces. However, studies indicate that raisins are rapidly cleared from the surface of the teeth, as are apples, bananas, and chocolate. Published in Pediatric Dentistry, a study involved children ages 7 to 11 years and compared 4 groups of food: raisins; bran flakes; commercially marketed raisin bran cereal; and a mix of bran flakes with raisins lacking any added sugar. Sucrose (table sugar) and sorbitol (sugar substitute often used in diet foods) were tested as controls. Children chewed and swallowed the test foods within 2 minutes. The acid produced by the plaque bacteria on the surface of their teeth was measured at intervals. It was found that all test foods except the sorbitol solution promoted acid production in dental plaque in more than 30 minutes, with the largest production between 10 to 15 minutes. There is a danger zone of dental plaque acidity that puts a tooth’s enamel at risk for mineral loss that may lead to caries, and plaque acidity did not reach that point after children consumed 10 g 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, reaching into the danger zone of plaque acidity. Plaque bacteria on tooth surfaces can ferment various sugars such as glucose, fructose, or sucrose and produce acids that may promote decay. But the bacteria also use sucrose to produce sticky sugar polymers that help the bacteria remain on tooth surfaces. Raisins themselves do not contain sucrose. In a previous UIC study, researchers identified several natural compounds from raisins that can inhibit the growth of some oral bacteria linked to cavities or gum disease.
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