Is chewing gum OK for teeth?

Though we can't eat chewing gum in Singapore, we might probably do so in other countries. But do you ever wonder whether chewing the chewing gum is OK for our teeth?
Let's find out from the article I found:

Gum has been around for a long time. The ancient Mayans, Greeks and Native Americans all nibbled a little tree sap now and then. Today, chewing gum is made up largely of synthetic ingredients, and it's really the ingredients in gum and how long it's actually chewed that determine whether or not indulging in a slice is a good idea.

The American Dental Association (ADA) acknowledges that chewing gum can help protect against tooth decay if used properly. If not used correctly, however, chewing gum can lead to tooth decay just like eating any other sugary treat.

Chewing, or mastication, encourages the production of saliva, and that can be a very good thing for your mouth. The human mouth contains lots of potentially damaging bacteria. Think of an increased flow of saliva as a cleansing shower for the teeth and gums. It washes away bacteria that can lead to inflammation and infection. From that perspective, chewing gum can be an aid in good dental care. That doesn't tell the whole story, though. Not all chewing gum is beneficial. Gum that contains sugar can cancel out any benefit from the increased production of saliva by coating the mouth with a sugary glaze, which is tasty for you -- and for the bacteria that causes tooth decay. It would be nice if the sugary gum residue were completely washed away by all that extra saliva, but instead, sugar gets trapped between teeth and around the gum line where it creates as many problems as having indulged in, say, a chocolate truffle.

Chewing artificially sweetened gum is a better choice, but to maximize the health benefits, gum should be chewed for 20 minutes or more, which is sometimes long after the flavor of many chewing gum products has faded. Chewing that slice of gum a few minutes longer has another benefit you should consider. The saliva produced when you chew gum does more than irrigate your mouth and remove bacteria. It contains calcium and phosphate that help strengthen and restore the enamel in your teeth, too.

The ADA tests chewing gum products for effectiveness and offers its seal of approval based on criteria like a gum's ability to reduce plaque acids and control gingivitis. To date, all ADA-approved gum products are sugarless. It's true that the ADA evaluates a gum based on its ability to help protect teeth rather than on great flavor or flavor staying power, but it still might be worth checking out a few good-for-you gum varieties. Gum is a very gentle and easy to use tooth aid. If you think of it as therapeutic rather than as a treat or breath freshener, you might buy a more effective product and chew it long enough to enjoy the flavor, freshen your breath and give your teeth a little well-deserved pampering [source: ADA].

American Dental Association. "Chewing Gum." 11/2010. (8/17/11). http://www.ada.org/5098.aspx?currentTab=1