They didn't really brush, but stuck the brush in their mouths and shook their heads
In the examining room at my new dentist's office, they had quicktime videos playing on hanging monitors to scare/distract patients about periodontal disease, etc. As luck would have it, the video playing when I was there was intended to teach children proper oral hygiene, and featured a chimpanzee brushing his teeth. It's an omen.
That, and he said my mouth is a "picture of health".