YOU could never accuse Mitchell Lichtenstein (son of artist Roy) of pandering to market expectations. His first feature, "Teeth," is a dark, gory and hilarious sendup of contemporary prudery, teen horror films, Christian abstinence programs, rampant cultural misogyny and latent gynophobia in ancient mythology that plays serial castration by vagina dentata for laughs. The movie re-imagines the ancient myth as the mortifying personal problem of a sweet, unsullied American teen who is having a hard time remaining unsullied and whose awesome powers are as big a surprise to her as they are to her date-raping boyfriend, only not as painful.

Dawn (Jess Weixler) grew up in the shadow of a pair of giant nuclear cooling towers, which may explain why her genitals have developed the ability to fend off intruders with their sharp monster teeth. Of course, Dawn, a Christian, doesn't believe in evolution either (at least not at first). Nor does she have a very clear idea of how things should look down there; the diagram of female genitalia in her health book is covered with a giant gold sticker to "preserve a girl's natural modesty," courtesy of the state school board. The fact that such things actually exist is far more shocking (and considerably more medieval) than any of the rampant dismemberment that follows Dawn's reluctant induction into sexual maturity.

Dawn lives with her groovy and supportive mother, Kim (Vivienne Benesch), and stepfather Bill (Lenny Von Dohlen), and her seriously maladjusted stepbrother, Brad (John Hensley), who spends all his time in his darkened, porn-lined lair listening to death metal and fighting with his girlfriend.

A motivational speaker for a teen abstinence group, Dawn speaks in public on the importance of remaining "pure" and lives by her credo despite getting pelted with food on her way into school each day. Her only friends are Gwen (Julia Garro) and Phil (Adam Wagner), a couple who apparently use abstinence as protracted foreplay. Dawn, naturally, feels left out until Gwen and Phil introduce her to Tobey (Hale Appleman), a cute and charming new guy who also happens to have made "the promise."

Lichtenstein mercilessly skewers the way the evangelical obsession with chastity results in people thinking and talking about sex constantly, putting them in a state of perpetual, hysterical excitement. When her friends suggest a trip to the local swimming hole, the ever-vigilant Dawn is wary. But her attraction to Tobey is more powerful than anything she's ever experienced, and she relents. When Dawn and Tobey visit the Edenic swimming hole again later, alone, Tobey is unable to contain himself any longer. Blurting out the funniest rationalization for sex ever uttered, he forces himself on Dawn, whose vagina takes care of the rest.

Because her vow prohibits her from even touching herself, Dawn has remained blissfully unaware of her "adaptation," as she begins to refer to it after some desperate Googling. In fact, nobody suspects anything but Brad, who suffered a primal horror years ago in the kiddie pool during a game of show-me-yours-and-I'll-show-you-mine.

Gleefully perverse as it is, "Teeth" is, at its core, a coming-of-age story about a girl dealing with her sexuality. Her sexuality just turns out to be a bit compromised. But as Lichtenstein has said, the vagina dentata myth, though it may have obscure medical origins, is really about projected fear. Weixler, a graduate of Juilliard in her first leading role on the big screen, is perfect as the goofy, vulnerable, deadly teen (she won the Special Jury Prize: Dramatic Performance at Sundance last year). Hensley, of "Nip/Tuck" fame, is equally impressive as Brad. Like most of the men in Dawn's orbit, including a pervy gynecologist (Josh Pais), Brad pays a price for his treatment of Dawn. And it's not a transaction for the squeamish.

Campy, shameless and sophisticated, Lichtenstein's debut is gutsy and original, and it makes "Juno" look positively tame by comparison.

carina.chocano@latimes.com

"Teeth." MPAA rating: R for disturbing sequences involving sexuality and violence, language and some drug use. Running time: 1 hour, 28 minutes. In limited release.