Why is Flouride put in our water supply?

Not the natural Calcuim Flouride but the toxic, synthetic Sodium Flouride which is considered to be a neurotoxin.

IMPORTANT! No. Preventing cavities isn't the answer, It's just a PR stunt that with the help of dentists became a fact. Countless researches have been done which without a doubt prove that people still have the samme issues with cavities in low and high flouridated areas.

Give me the real answer. Dig deeper :)