[ssaftler]

but are you sure Nickleson was the dentist?

Reread my comment. Nicholson was the dental PATIENT. Don't remember who played the dentist, but it wasn't anyone very memorable, much like most of the cast.

[Mercat]

I think it was Jonathan Haze aka Seymour. It was Nickleson’s first screen credit. He came in the shop at the beginning.