The effect of xylitol on dental caries

Both the short and long term beneficial effects of xylitol in dental caries prevention appear to be mainly related to decreased adherence of the plaque to the tooth surfaces. In vitro, xylitol modifies the synthesis of polysaccharides from sucrose in Streptococcus mutans, thereby decreasing the ability of streptococci to adhere to hard surfaces. In long term habitual use some loss of sensitivity of mutans streptococci to xylitol occurs, but the ability of “xylitol resistant” streptococci to cause caries in the presence of glucose is still lower than that of more xylitol-sensitive streptococci, a result, the long term use will change the prevalent strains of mutans streptococci to strains with decreased ability to cause caries. In addition, the levels of mutans streptococci on tooth surfaces and the plaque are decreased by an order of magnitude over a long term course of habitual xylitol consumption as in chewing gum. This is probably mainly due to the low adherence of the plaque and not due to the intrinsic inhibition of mutans streptococci, since the bacterial counts in saliva are essentially unaffected in long term use of xylitol. However, unlike six-carbon sweeteners, xylitol is not metabolised by the streptococci. Positive effects of xylitol consumption on dental remineralisation have also been reported. Chewing gum sweetened with xylitol appears to be an effective vehicle to introduce sufficient amounts of xylitol to the tooth surfaces. The sufficient dose is suggested to be about 8 g/day.