We buy the large chews and give a third of one to our dog when we go out. He's not the slightest bit bothered about us leaving as all he wants is the chew. He has less tartar since having these so we're all happy.
I can't say whether these chews are helping the dogs teeth but they certainly love them. I think they're quite expensive so they only get one once a week.
This an excellent product and will continue to buy them, despite (I think) being over priced. My dogs love them, its their favourite treat and have them 4 / 5 times a week. What more can I say ? They're great !!