Tooth-friendly sweetener.

As unbelievable as it may sound, some chewing gum may actually halt the progress of tooth decay. Gum sweetened with xylitol, a caloric sweetener made from cornstalks and found in small amounts in fruits and vegetables, promotes the sealing of new cavities, says Kauko K. Makinen, a biochemist at the University of Michigan in Ann Arbor.

Makinen's three-year study involved 1,200 children age 9 to 11 in Belize. First, dentists counted the cavities, as well as missing and filled teeth, in each child's mouth to come up with a "DMFT" score. They reexamined the teeth after 16, 28, and 40 months.

Under their teachers' guidance, these children chewed gum for several minutes three to five times a day.. The children received gum sweetened with sucrose, xylitol, or sorbitol (another sugar-free sweetener). DMFT scores increased from an average of 5.5 to 6.5 for children chewing gum containing sorbitol, to 8.0 for children chewing sucrose gum, and to 7.5 for a control group of children who chewed no gum. But in children chewing xylitol gum, the score dropped to 4.0.

Bacteria do not readily break down xylitol, so chewing that gum yields little of the acid that causes cavities, Makinen says. He reported the results in Chicago last month at a meeting of the International Association for Dental Research.