Once a year, the school dentist and a representative from some toothpaste company, probably Colgate (as are they all, all Colgate,) made the rounds of the classrooms on their zero tooth decay campaign.
They gave lectures on proper brushing (i.e. do it) and handed out free toothbrushes and little tubes of single-use toothpaste that ended up in the bottom of bags and hardened into little tubular rocks.
That was all par for the course in eliminating tooth decay, and was a welcome respite from the rigors of, say, learning the major exports of Philippine provinces (copra and abaca, generally.)
What was scarring about the whole thing was the part where kids were made to let bitter-tasting pink tablets melt in their mouths. The tablets would supposedly mark plaque buildup and, incidentally, rape your taste buds.
Supposedly, you were supposed to brush harder in the areas that were pink to get rid of plaque and have cleaner, whiter teeth. Never mind that your mouth is now stained pink and will probably remain so the rest of the day, also, your mouth is pretty much useless for things like eating and drinking.
The idea, I guess, was to make the plaque test so unenjoyable that children would opt to brush their teeth regularly. Or develop a subconscious fear of dentists that will limit dental checkups to those required by insurance companies. You can never really tell with childhood trauma.
One upshot is you got to take home a plaque detection tablet of your own to, uh, bring the fight against cavities to younger siblings and runtier kids in the neighborhood.
In this aspect, at least, they got the Filipino psychology right: we are naturally concerned for the wellbeing of others. Also, when we put something in our mouths that tastes like crap, we can be counted on to share the experience with others. By force, if necessary.