I'm not such a great toothbrusher (bad mom) but I have had great luck using the Oxyfresh Pet Oral Hygine Solution that you add to your pet's drinking water. It work to keep the tarter off their teeth but works best after you have a dental cleaning done. My 15 year old Yorkie has only ever had to have one dental cleaning. She is missing a few teeth but the rest aren't too bad. I'm out of the solution right now and need to find a new place to order from but I'll be getting some more.
The other thing I like to give my dogs is the Virbac C.E.T. chews. They are completely digestable and have enzymes that help kill mouth bacteria and the chew scrapes any tarter off. (the 15 year old won't chew them but the others will). The package says you can give them daily but I just give them every other day. My dogs love them so much that they line up and wait for them when they hear the bag crinkle.
I order the petite size (30 chews in a package) from
entirelypet.com I've had really good luck with these chews
Teresa