Have you seen the movie Teeth?
When virtuous high school student Dawn (Jess Weixler) becomes the victim of a sexual assault, she discovers that she has an unexpected line of defense: a toothed vagina. But for Dawn, coming to terms with the power and dangers of her anatomical anomaly may be easier said than done. Director Mitchell Lichtenstein's provocative feminist horror flick also stars John Hensley, Hale Appleman and Josh Pais.
Teeth is available on DVD, and the above description comes courtesy of Netflix.
Oh. And here is a bit more on the whole (hole?) Vagina Dentata myth.