Novocaine (2001)

In his first tooth-tinkering role since 1986's ''Little Shop of Horrors,'' Martin plays a docile D.D.S. with a thriving practice and an adoring, obsessive-compulsive dental-hygienist girlfriend (Dern). But when a mysterious patient (Bonham Carter) cons him into prescribing drugs for her, he finds himself part of a bizarre murder plot that's ''extremely dark, hysterically funny, and pretty sick,'' says Dern, who, thanks to her ''Wild at Heart'' and ''Citizen Ruth'' experiences, is pretty familiar with the whole dark-funny-sick gambit. She's also now equipped to help repair a bicuspid or two, having attended a hygienist's training school in Los Angeles while researching her role. ''It's pretty wild,'' Dern says of her time learning the drills. ''You actually have to be obsessive-compulsive -- everything has to be meticulous, and in the cleanest environment possible.''

Still, that's about as sterile as this kinky comedy, which will have its premiere at next month's Toronto International Film Festival, promises to get. And while ''Novocaine'' offers a change of pace for the usually wild-and-crazy Martin, he made sure the material wasn't all molars and misery. ''Sometimes, when comedies are this dark, it's hard for people to know that they're allowed to laugh,'' says Dern. ''But because he's Steve Martin, he lets people see the humor in the sickness of the situation.''