Actually, that has never been a problem. A stiff upper lip requires a conscious muscle command, which everybody can easily withhold.Algot Runeman wrote: ...
[E.P.S. Just how does a dentist deal with a patient with a stiff upper lip? It must be difficult to get at the front teeth!]
But a stiff lower lip is an entirely different pair of sleeves, so to speak.
Some people have a kind of reflex whereby they tighten the lower lip muscles, completely covering the labial surfaces and incisal edges of the lower front teeth and making access quite impossible.
For mild cases and simple procedures (removing calculus, cleaning, polishing) the solution was easy. I gave them a hand mirror and asked them to watch what I was doing.
The intermediate cases could be handled with a rubber dam (applied on the lower teeth only of course).
But the strong stubborn cases overcame the rubber dam's tension and required a mild local anaesthesia. (the anaesthetic also temporarily paralyses motor neurons and relaxes muscles)
So when you visit the dentist feel free to fake a brave demeanour, but please DON'T keep a stiff LOWER lip.