Lockjaw (trismus) is a painful condition that limits your ability to open your mouth all the way. It occurs when the muscles you use to chew spasm, meaning they can’t relax completely. The term ...

Dear Eric: I play cards weekly with a group. One of the women sometimes chews gum during our games, noisily and with her mouth open. This is worse than fingernails on a chalkboard to me. Why do ...

That slightly open mouth while concentrating. The subtle parting of lips during sleep. The tendency to breathe through your mouth instead of your nose during exercise. These seemingly innocent habits ...

Dolphins living in captivity often make an open-mouth facial expression while playing with each other. Zoomarine, Italy Bottlenose dolphins “smile” at each other while playing, making open-mouth ...