Puppies chew, that's what they do, especially when they are teething. Using a spray on him won't help him, you need to get to the root of the problem by interacting with him or giving him something else to do. He needs to be stimulated, to have plenty of exercise, not to be left too long on his own. Just telling him to stop is no good, you need to give him something else to bite on. rsvp has given you some excellent advice, a Kong, used as she has advised, should help soothe his sore gums. Good luck.