Start a habit of chewing gums which contain Xylitol, a natural
sweetener that has been proven to be an effective help against
tooth decay! There are currently 3 brands available in Singapore
pharmacies (eg. NTUC pharmacy, Guardian Pharmacy, Watson's
Pharmacy, etc) - Orbit, Impress and Xylit.
Orbit is too hard, Impress is salty (yucks!), so the best tasting
chewing gum by far is Xylit, image here :

If you haven't read about this amazing tooth decay prevention
sweetener called Xylitol yet, start reading now! Chewing Xylitol
gum after meals, quickly neutralizes the acidity caused by
bacterial activity, and prevents tooth decay! And buy a box of
Xylitol containing chewing gum for your girlfriend/boyfriend
tomorrow!
For more info on Xylitol, see here,
here and
here.