There are fluoride rinses sold in the U.S. (like ACT)--maybe some are available in Singapore. You swish with these rinses for a minute or so after brushing your teeth. But make sure the rinse has fluoride--a lot of them don't.
Strongly recommend you get your fluoride from somewhere. Dentist told my wife that lots of kids drinking bottled water these days are having more than their share of cavities. I rarely got fluoride as a kid (due to living in non-western countries), and in spite of all of the obsessive care I give my teeth, I have all kinds of problems.
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Resis