Welcome to YorkieTalk.
I don't think that there is one quality kibble out there (to my knowledge) that is used for tartar control. In fact, I"m not even sure kibble prevents plaque at all. My Yorkie ate mostly kibble for the first five years of her life and she has horrible teeth. My suggestion would be to brush your dog's teeth or use Petzlife Oral Gel. Ellie had nine teeth pulled in January. She was then switched to homecooked food in April. Homecooked is all soft. Ellie's vet is really big into the whole dental thing and she doesn't have a problem with the soft food so I'm not sure that you switching food will actually help but I can't be sure. Maybe start brushing instead? Of course, you should always listen to your vet first though, not me.
