Dentist Visit
The other was in “Apocalypse Rising” where he had to play a Klingon.
There were so many prosthetics that he even had to visit a dentist to have the mouth pieces and teeth put in place. He really didn’t want to, but the studio gave him no choice. If you watch the episode, the discomfort he’s showing isn’t just the character’s aversion to suddenly being Klingon, it’s the actor’s hatred of being in the makeup.