Possibly something to chew on if it is to feel inside the jaw. If it is his proprioceptive sense, and he just wants to feel the outside pressure on the chin, maybe applying pressure to his chin and the top of his head and gently squeezing them together will help. My son loved when I did that to him...now he does it to himself when he feels the need.

Dont give up eventually you will find what works.patience is key

Blowing through a straw to play cotton ball soccer on a table or use a very long crazy straw to drink liquids. Blowing bubbles or trying to keep a small ballon afloat with your breath. Is your OT familiar with the Beckmann Oral Motor Assessment &Intervention?

My 3 year old is in speech therapy for sensory delay and his therapist has suggested: licorcie (hard, left out for a day), pretzel sticks (bite & chew on one side at a time), use a tooth brush all over inside of his mouth. Pretty much anything that makes him chew more.

Crimsonwife we tried the chewie tubes and other chewies and he hates them won't even put them in his mouth. He looks at us like we were crazy when we showed him what to do with it. We have a vibrating toothbrush (it's not a spin brush it just vibrates) he loves that but he will only let us brush his teeth 3-4 times a day. It's very frustrating for me that a lot of the stuff we try he doesn't seem to like. He has Ot today I'm going to ask again and see if they have any other suggestions.