The mouth is a really useful tool to handle the nervous system. Puting things in your mouth is a way to stimulate et redirect its attention and help you get more relaxed. There is chew jewelry made for autistic and other flavors of neuro spicy kids and adults. Be aware that only chewing gum has been scientifically demonstrated to be a useful thing to reduce anxiety and help focus. The rest is anecdotal evidence (doesn’t mean it don’t work).