I use CET chews which have an enzyme on them to help retard plaque. They were recommended by my vet. You can buy them online at
EntirelyPets Discount Pet meds Pet Supplies & Flea Medicine, they seem to have the lowest prices on them. As with any chew you must supervise your pup when you give them to her and take it away when it gets too small so that she doesn't ingest the whole thing.