I use a product called Life for Teeth and spray in Maddie's mouth each day. If your dog has tartar or plaque, this would clear it up and I believe it also helps with breath. There is also a Brush Away gel that you can brush the teeth with. I have that too, but mostly use the spray. Maddie is about 20 months old and I've been using this for about 5 months. She's never had plaque or tartar on her teeth and I think it's because I'm using the Petzlife products. My sister started using it on her dog that did have a lot of plaque or tartar and they are totally white again! Hope this helps...I think it's great stuff and lasts a long time too!
http://www.petzlife.com/