There are two rules in Hollywood: comedies about dentists fail, and dramas about pirates fail twice as hard. Hence the lack of movies that concern oceangoing orthodontists who board each other's ships and engage in hand-to-hand flossing. Why pirate movies bomb I can't say, but it's obvious why dentist movies choke: The very subject makes a large portion of the population shudder with dread. Dental pain is so intimate. The very act of dentistry is somewhat embarrassing. Hello, how's the family, is that a new dog in this picture? OK, shove your hands in my mouth.