The buzz on American Teen — a documentary feature that follows four small-town Indiana high schoolers through their senior year — was quite high cominginto Sundance. That much was clear as festival officials jammed as manybodies as they could into the 448-seat Library Center theater. And by the roarof approval from the audience at the end (not to mention the huddles ofpotential buyers both inside and outside of the auditorium), I’d say the fest has perhapsits first true hit. Expect more tomorrow after I speak with director Nanette Burstein andthe students in the film. —Adam B. Vary