1. Little Shop of Horrors. Steve Martin plays my favorite dental character, Dr. Orin Scrivello DDS. An insane comic sadistic dentist who rides a Harley and pulls the head off a little girl's doll.
2. The In-laws. Alan Arkin plays Sheldon Crompett DDS against defrocked CIA agent Vincent Ricardo played by Peter Falk. Perhaps the best "fish out of water" comedy of all time. "Serpentine Sheldon! Serpentine!".
3. The Whole Nine Yards. The film that made Matthew Perry for me. Doctor "Oz" Oseranski misses getting killed by several professional killers with his talent as a nice guy, and the help of Jimmy T. (Bruce Willis), a retiring hit-man.
The In-Laws had a remake a couple of years ago, but the original was so perfect, I saw no reason to see re-do. There was also a sequel called The Whole Ten Yards, but for the same reason I've never seen it.
There must be more dental themed movies out there, but I can't recall them.