He had caused a decent amount of damage to the side of the crib before I had even noticed. I didn't want him eating his entire crib during the night so I found Kidkusion Gummi Crib Rail
. It claims to be BPA, phthalate and vinyl-free. I can't find any information to the contrary, so I'm believing them. For the most part I think it serves as a deterrent from chewing the side, although I have seen him enjoy an occasionally chomp on the gummy surface.
It's a big rubbery strip with adhesive on one side. It went on very easily and bonded quickly. The box says that when you need to remove it, just heat it with a hair dryer. Easy! If only I had got it sooner...