The parotid duct pierces through the buccinator muscle on its path carrying saliva from the parotid gland into the mouth. Some sources mention that the buccinator muscle acts as a sphincter for the parotid duct. This is not one of the main functions typically listed like positioning food during chewing, suckling, whistling, etc., but I think it might have significance in the buccinator hypertrophy that prevents cheek hollows. Dr. Mike Mew focuses on correcting swallow patterns to atrophy the buccinators, but for some people, perhaps contractions of the buccinator muscle to expel saliva from the parotid duct could play a significant roll in the persistence of hypertrophy.

Eating sour foods seems to reflexively contract the buccinator into a pucker expression, perhaps to discharge saliva from the parotid duct and dilute/neutralize the acid. I enjoy consuming a lot of sour foods and drinks. When I think about it, I can feel the activation in my cheek area when I taste something sour. I've been conscientious about correcting my swallow pattern without seeing much improvement in my cheek hollows. Do you think this sour pucker reflex could be to blame?