If you're looking for a "tooth friendly" gum, check out sugarless chewing gums sweetened with xylitol (zi-lo-toll). Xylitol is a non-fermentable sugar alcohol that apparently helps to remineralize - and strengthen - tooth enamel before cavities can form.
Xylitol has other benefits, too. Recent studies show that xylitol has a plaque-reducing effect. And for people with "dry mouth," chewing gum sweetened with xylitol helps stimulate the salivary glands, helping to "wet the whistle," so to speak.
For the best results, gum containing xylitol should be chewed for at least 5 minutes 5 times a day.