The optimum time to initiate habitual xylitol gum-chewing for obtaining long-term caries prevention

Habitual xylitol gum-chewing may have a longterm preventive effect by reduc ing the caries risk for several years after the habitual chewing has ended. The goal of this report was (1) to determine if sorbitol and sorbitol/xyli tol mixtures provide a long-term benefit, and (2) to determine which teeth benefit most from two-year habitual gum-chewing-those erupting before, duri ng, or after habitual gum-chewing. Children, on average 6 years old, chewed gums sweetened with xylitol, sorbitol, or xylitol/sorbitol mixtures. There was a "no-gum" control group. Five years after the two-year program of hab itual gum-chewing ended, 288 children were re-examined. Compared with the n o-gum group, sorbitol gums had no significant long-term effect (relative ri sk [RR], 0.65; 95% confidence interval [c.i.], 0.39 to 1.07; p < 0.18). Xyl itol gum and, to a lesser extent, xylitol/sorbitol gum had a long-term prev entive effect. During the 5 years after habitual gum-chewing ended, xylitol gums reduced the caries risk 59% (RR, 0.42; 95% c.i., 0.23 to 0.75; p < 0. 0034). Xylitol-sorbitol gums reduced the caries risk 44% (RR, 0.56; 95% c.i ., 0.36 to 0.89; p < 0.02). The long-term caries risk reduction associated with xylitol strongly depended on when teeth erupted (p < 0.02). Teeth that erupted after 1 year of gum-chewing or after the two-year habitual gum use ended had long-term caries risk reductions of 93% (p < 0.0054) and 88% (p < 0.0004), respectively. Teeth that erupted before the gum-chewing started had no significant long-term prevention (p < 0.30). We concluded that for l ong-term caries-preventive effects to be maximized, habitual xylitol gum-ch ewing should be started at least one year before permanent teeth erupt.