There are teething necklaces that moms can wear for babies. One of my boys likes to wear it and chew on it. It has a cord that is like the shirt they can chew on and a hard round ring. To break of the shirt. Try putting the thumb sucking stuff on it (comes in liquid form at a drug store). Or take a heavy duty cord and braid it together to make a necklace to chew on.

We are dealing with this issue also. I tried a couple types of Chewelry and he likes one of them. He didn't care for the spiral phone cord necklace, so we are using a knotted fabric instead.

You may want to speak yo his teacher or an occupational therapist for suggestions.

Yes, we dealt with this for a period of time last year, lasted probably about 6-7 months. It is a sensory issue. We tried several type of chewy tubes, etc and the one thing that worked was something that looked like a telephone cord (spiraled). He could wear it around his neck if needed and could chew on it. The phase passed for my son but he still likes to play with the chewy.

My son was given a band of medical tubing that he wore for the better part of 3 years to early childhood and preschool. After starting kindergarten he was switched to gum. It is a sensory issue. Add other sensory activities that sooth, perhaps swinging, heavy weighted dog toy on his lap, jumping on an small exercise trampoline, pedal riding toys, swimming are other ideas for sensory.