Is vigina dentata true?

I've watched the movie "TEETH" starring Jess Weixler, the movie is so confusing i dont understand why does a vigina have teeth that can chop off a whole while having . I really thought that movie is not true but when i researched in google, yahoo, and wikipedia....it is true there is such thing as vigina dentata. I dont know if some women has these case, because it is the first time i heard this cause, because if this case would be helpful to learn about its not included in reproductive system. Can anyone help me tell this cause if this is really true or not?....Even inserting fingers inside the vigina with teeth can chop off because there is teeth inside...Im so curious.