Yep you can use a clicker for that too. I used a clicker to help me touch both of my dogs mouths, to brush their teeth, look at their teeth, touch their feet, hold their head, etc. when needed.
I'll give it a try - maybe I can find a different clicker, one with a softer pop. It's funny sometimes how the cookie crumbles - I can't show Trinity, yet she's the one who lets me get right in her face, in her mouth, stands still when I want to inspect her…:p