From the NY Times
Asked – Answered:
Published: October 6, 1981
Q. Why is toothpaste sweet and what is it sweetened with?
A. In order for toothpaste to be effective, it must be used regularly. Research has indicated that a sweet taste encourages the regular use of toothpaste.
Specific flavors have been found to appeal to certain groups of the population. A sweet combination of flavors seems to be the most appealing. Sugar, however, is not used as a sweetener in toothpaste. Most manufacturers use an artificial sweetener, usually saccharin.