Nazo Nazo (riddle)

[jazmin_firewing]

Got a riddle for ya.
Whoever guesses right gets a prize.
No, not telling what it is.

I turn my head, and you may go where you want.
I turn it again, you will stay 'til you rot.
I have no face, but I live or die
by my crooked teeth -- who am I?

No guessing if you know the answer!