Some Yorkies (or dogs in general) will have genetically bad teeth no matter what you do and some need professional cleanings once a year. However - it's definitely a great idea to keep up with them to prevent decay and tarter as much as possible.
I've never heard of that spray but I like Petzlife as well as HealthyMouth (this is approved by the VOHC - veterinary oral health council). I also like Proden Plaque Off and Vetrscience Perio powder. CET toothpaste is my fav for Jackson.