"It's your professionalism that I respect!"
Arthur Denton (played by Bill Murray in the 1986 movie) is a masochistic patient who goes to Orin Scrivello D.D.S's dental service, because he actually enjoys the pain that Orin inflicts. This causes Orin to become angry and kick Arthur out of the office.
Arthur became interested in dentistry as a child, when a dentist gave him a candy bar after his checkup. This bizarre reinforcement of negative behavior profoundly affected the lad, who quickly became obsessed with dentistry. As he grew older, so did his obsession with pain and reward, and he seems to visit a different dentist daily, preferring a blind female dentist who extensively roots around in his mouth.
Arthur Denton is loosely based on Wilbur Force, a character whom Jack Nicholson portrayed in the original film. Wilbur was cut from the stage musical but this character was introduced for the film adaptation, and producer David Geffen specifically requested Murray for the role.