After one week my dog went to the vet with an intestinal blockage. Vet said that he sees this often with these chews. They are meant to be well chewed as the chews are very dense. If your dog doesn't take the time to really chew them (as most dogs don't), then it can end up getting stuck in their system.
My dog loves to eat Greenies. However, even with the right sized Greenie he finishes in basically a couple chomps. I'm not sure how much "brushing" actually gets done. They don't last very long. He just loves the taste and that's it.
They are a mint flavored treat. They won't clean your dogs teeth any better than any other "chew" treat. Granted my pup does like them and I don't mind giving them to her. However the price has simply skyrocketed in less than 10 months. Almost double, if not more depending on size/quantity. Until the price comes down to earth I don't see the point in even buying these.
I bought these for my 17 lb pug. He loves them, but they seem very large to me. I keep him on a strict diet, because as you know pugs can get fat easily. I break them in half and only feed him half of one per day. Not sure that I have noticed much of a breath difference. Probably wouldn't repurchase, because they are quite pricey.