[Jkpal]

Piper's groomer brushes her teeth which helps somewhat...I also use a dental spray from Nylabone called Advanced Oral Care Dental Spray (with denta-C) which Piper pretty much hates. However, since I only use it when we're going out or when company's-a-comin' she bounces up readily as I shake bottle (I don't fake her out with stuff she finds unpleasant) She knows the sooner she comes and sits next to me, the sooner we're "....Allllll done...!" and then it's on to the fun stuff. Per directions, I spritz each side of her mouth while her mouth is closed.
There are also additives to drop in water dish and that seems a popular option.