Not drinking 4 cups of coffee a day for 20 years.

Toilet brush

It seems like it's the same as the Deodorant Dilemma: a. chemical that works but poisons you irrevocably b. natural method that everyone swears by but doesn't really work

Eat more fibre, less sugar. Drink lots of water. You can use super fine grit charcoal mixed with coconut oil to polish teeth but this will wear them down and destroy the enamel if you are not careful. Oiling pulling after brushing teeth will also help; Swish coconut oil/tallow or some other minim...