T.Y.
You could offer him real knowledge of bacteria and the possibilities of what could happen to his teeth. Maybe show him a couple of tame examples from a book or the internet. Find a kids book that talks about it. Plus, have him pick out a replacement soother- stuffed animal, blanket or a toy that he can chew that won't hurt him. Maybe even soft music to play in his room at night. A fun lamp that has a night light. Ask him what would help? "If you could have something that would remind you that you're big enough not to suck your thumb or You will always be mama's baby...I'm not sure but you will know your child." Good luck and best wishes.