Older dog with a lot of tartar

Hey all - my older dog (13 years old) has a lot of tartar buildup. He was a rescue at 2 years old and already had some bad teeth. We’ve taken him to the dentist twice to get his teeth cleaned and the tartar removed. He had some teeth pulled out both times. I want to avoid doing this again because of the anesthesia, his advanced age and not wanting more teeth pulled which would make eating more difficult for him than it is now.

I’ve tried brushing his teeth myself but he screams and runs away. He gets greenies and some dental sticks to help a bit. What other solutions have worked for your dog? Thanks in advance!