Yep, already been said but their teeth constantly grow so they need to wear them down. I find bunnies like to chew on their hutches because they can get a secure grip on the wood and it doesn't move, so you could zip tie a piece of wood to the cage so he hopefully chews that instead.
Is he getting plenty of hay, Bandit doesn't seem to chew a great deal, but he is constantly downing quite course hay.