Do we really need fluoride in our water and toothpaste? isn't it a poison

Not really: Fluoride is not a poison unless you ingest a lot. But too much of anything (even water) is not good for you. Fluoride levels in water are ideal for your teeth and bones, but impossible to become poisoned by because the amount of water you'd have to drink would kill you first. Fluoride in toothpaste is at high levels, but toothpaste is not meant to be swallowed--it has a surface effect only.

Yes - No: Yes - the Fluoride in the water and toothpaste really does reduce the amount of cavities. No - it is not poison in that low of a dose.

Yes we do.: No it is not a poison. We take very little Fluoride through water and don't ingest our toothpaste hopefully. It's important to fight the bacteria that causes decay. Also helps keep our bones strong!

Needed, not poison: Our teeth constantly lose minerals when ever we eat and pick them back up between meals. Small amounts of Fluoride found in water and toothpaste help teeth to pick up minerals and also make it harder to lose them. New teeth benefit the most. Despite lots of fear-mongering this small amount of Fluoride is perfectly safe. Proper amount is based on age so infants should not use Fluoride toothpaste.