In an action that will surprise many, the American Dental Association (ADA) has endorsed chewing gum to help prevent cavities. If there's any habit dentists have been warning against for generations, it's chewing gum. So why the apparent U-turn? The difference is that the ADA is espousing the use of sugarless gum, particularly gums sweetened with the sugar alcohols xylitol and sorbitol.
Further, it appears xylitol may be slightly more effective than sorbitol. Recent research from Sweden (Holgerson, et al., Int J Paediatr Dent. 2007 Mar; 17(2): 79-85) compared the presence of dental plaque (the sticky substance produced by bacteria that holds them on the tooth surface) and the level of bacteria in two groups of children, one given pellets of xylitol and another given pellets of two other sugar alcohols -- sorbitol plus maltitol. The kids received two pellets three times per day for four weeks.
While both groups showed a significantly decreased amount of dental plaque by the end of the study, the xylitol group also had significantly lower levels of the bacteria most responsible for cavity formation.
Because of such studies, as well as those showing that any chewing gum will increase the flow of tooth-cleansing saliva, the ADA chose to endorse sugar-free gum. So while it may seem counterintuitive, perhaps a good way to help children avoid cavities is to encourage them to chew gum -- especially xylitol-sweetened gum -- after meals.
See also: ACSH's A Primer on Dental Care: Quality and Quackery.