Most sugarless gum contains a sugar substitute called xylitol.
A recent study through the University of Montreal examined school children who were given xylitol gum and the effects on their teeth over a two year period. One group was given higher amounts of xylitol than the second, while the third group did not receive gum. Results from this study showed that the regular use of chewing gum containing xylitol or a combination of xylitol and sorbitol, another sugar substitute, reduced the amount of tooth decay in children who were not chewing gum. In fact, in some cases it appeared as though the chewing gum may actually be reversing tooth decay and was helping to rebuild the teeth. A follow-up to the University of Montreal study five years later showed that the children who chewed the xylitol gum had fewer dental problems than the group that did not use gum.