How can I get my rabbit to stop grinding its teeth?

grinding teeth are something rabbits have to do to keep their teeth down. if they don't it will be very uncomfortable for them. my rabbit like chewing of this edible log. here is a web page for one. its called snak shak http://cgi.ebay.com/8in1-Snak-Shak-Edible-Activity-Log-Guinea-Pig-Rabbit-/140495237606 my rabbit loves it and has chewed up his first one. there are different snak shak items that are edible your rabbit would just love. it helps there teeth stay low by chewing on it.