[schoen]

> One that changes color based on where the calculus on your teeth accumulated, so you can target you brushing.

This exists, although for some reason I'm not aware that it's available as part of a toothpaste. (Maybe the toothpaste foam would create false positive indications by making it seem to accumulate in places that don't actually have plaque.)

https://en.wikipedia.org/wiki/Disclosing_tablets

[demondemidi]

Blast! I was hoping readers would be too young to remember and I would get the credit. \O_O/ ... I used to get these from the dentist as kid in the 70's.