Season 4, Episode 17: Last Exit to Springfield
When Mr. Burns decides to axe the dental insurance employees at the power plant receive, it couldn’t have happened at a worse time. Lisa needs braces, but since they no longer have insurance to pay for them, Lisa isn’t able to get the top-of-the-line braces she was hoping for. It doesn’t help matters that Lisa’s dentist tends to come off as a tad sinister.
Finding someone to provide a voice for the dentist proved to be a bit of a challenge. First, producers had offered the part to Clint Eastwood, who turned it down. Anthony Perkins later accepted the part. Unfortunately, Perkins died before he was able to record his lines. In the end, the dentist’s voice was provided by Hank Azaria instead.