Our 1 yr. old is starting to bite on his wooden rail of his crib.What can we do to prevent any other marks?

He can stand in his crib and has just been starting the past couple days now-putting his teeth marks on the crib. It's like he tries to chew on it or something. This is the first and we give him a pacifier before we put him down for his big sleep for the night. What would be best t o do in order for the crib to not have those teeth scratch marks all over the furniture? We want this to be carried down to our next little one in years to come....