Answer:
I drift forever with the current and flows to your everyday life. I make living easy but I am good at killing people too.
A dragons tooth in a mortals hand I kill I maim I divide the land.
I destroy your home from the inside out.
I turn everything around but I cannot move. When you see me you see you!
I'm white and used for cutting and grinding. When I'm damaged, humans usually remove or fill me. For most animals I am a useful tool. What am I?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.