Besides the good ideas already here, make sure he has lots of different, safe teethers. (Before you shop, check www.cpsc.gov for kids' items and see if any teethers have been recalled!) Then go to Babies R Us or other baby stores with lots of choice and get him several teethers so he has different shapes, textures, etc. Get some that are freezable so that gives him a different feel. Hand him one constantly, especially as he's teething so much right now. Have new ones in reserve so if he seems bored with the ones he has, you can present a new one immediately and get his interest before he returns to the wood. I too would be worried about both splinters as well as the furniture varnish he's chewing and licking off along with the wood. As for using a padded cotton cover for part of the crib or the towel that's taped on -- those sound OK but be absolutely sure he can't get a chunk of the filling or covering or tape into his mouth -- that's a choking hazard.