Don't give rawhides or greenies, they both pose choking hazards since dogs can break off chunks of them. Try giving a large raw beef bone each week with some meat still clinging (I buy big bags at a local butcher inexpensively and keep them in the freezer). Also provide Bully Sticks and Flossies to chew on, most dogs love them and they are great for cleaning their teeth, plus they are safer than rawhides and many other chews. I took in a rescue a couple months ago, the vet originally said she had dental disease and needed a teeth cleaning badly, she had lots of tartar buildup, but within 2 weeks of starting her on the raw bones, bully sticks, and flossies, her teeth were shiny clean and white and the vet said she didn't need a cleaning any more! So, they really do work. I have also heard that raw chicken necks can help, but I have not personally used them.