“Teeth” is a brisk, gory comedy about a chaste suburban teen endowed with a kind of fanged guillotine in her vagina. This former 2007 Sundance offering is best enjoyed as lightweight camp entertainment, as if it were a B-horror flick with a sense of humor, instead of the tonally risqué fable of sexuality that first-time director Mitchell Lichtenstein halfheartedly pitches.

Christian schoolgirl Dawn (the appealing Jess Weixler) is a likeable, apple-cheeked goody-two-shoes, the star presenter for a Promise Keeper-style virginity club and, as she’ll come to learn, the first medically documented case of the vagina dentata myth. While she can win over a gym full of middle-schoolers with a faux-casual rap session about saving one’s “gift,” she appears to have only two simpering supporters among her high school classmates. The rest are horny, crass, or oblivious and, in two cases we know of, deviously plotting behind those po-faces to get into her pants.

It doesn’t take a spring-activated Freudian to see where this is going, but the gambit of “Teeth” is to make Dawn’s special features a phased discovery for her. First blood is an encounter with Tobey (Hale Appleman), an admirer who professes to be fighting the same good fight against hormones. Splish-splashing at an Edenic waterhole leads to kisses and snuggling in a mossy cave. Tobey, whose queasily focused stare set my James Spader alarm bells off early on, ends up forcing himself on Dawn.

The rest is history, as is Tobey’s manhood. At this point, Dawn doesn’t know what she’s capable of, but she moves toward autonomy after a few minutes on the Internet (“female genital mutation” — a regrettable pun) and another inadvertantly bloody encounter, this time with a nebbishy gynecologist.

Meanwhile, family life is a drag, thanks to her mutton-chopped, troglodytic stepbrother Brad (John Hensley), who blasts thrash metal over her Christian rock. The owner of a Rottweiler named Mother, Brad is at once ridiculous and revolting, and a conduit for many of the film’s missteps toward shock and fraught, piled-on significance. As for his origin myth, an opening childhood sequence in a kiddie pool has Dawn biting Brad’s finger off in the manner to which she eventually becomes accustomed.

The final two episodes in Dawn’s path toward self-knowledge teach her that she can actually control her gift, so to speak. Good sex with a dork (even if foreplay appears to take place while she’s passed out) goes off without a hitch; when said dork subsequently betrays his actual awfulness by gloating over the cell phone during sex, it’s off with his head. Cue Mr. Lichtenstein’s spastic, nauseating rush to get abusive Brad and empowered Dawn together and fully realize a revenge fantasy (motivated by a distasteful, ham-handed development involving her sickly mother).

“Teeth” amounts to a modern retelling of a myth as unsubtle as Medusa (who appears on television in one scene), but without the bold clarity or resonance. Mr. Lichtenstein may think he’s made a movie about dangerous desire, cartoonish empowerment, and the like, but fundamentally, “Teeth” is uncritically playing out a nightmare of alienation from one’s body.

Some may see a double standard in that Dawn’s deluxe apparatus is never actually shown, while unhappy phalluses are strewn left, right, and center. But that’s consistent with its being first and foremost an overdeveloped metaphor. Mr. Lichtenstein, an actor (and, in case you’re curious, son of the Pop Art artist Roy Lichtenstein), delivers a sometimes diverting debut, but it’s tempting to wonder what someone like Takashi Miike might have done with the grindhouse premise. Aficionados of the vagina dentata myth will have to return to waiting for their masterpiece.