I brush Kacee's teeth. I wasn't able to do it nightly the last few years because of other obligations and lack of time until recently, but now we are on a nightly schedule again. We use Petzlife gel, too, as well as the spray.
I looked the following up and thought I'd post it fyi.
Do I have to brush my Yorkie's teeth?
Some dogs teeth form placque faster than others...and yes you should brush at least once a week with Nolvadent (from your vet or supply house) and put a drop of glyoxide (from your pharmacy) on either side of the mouth in back once a week and get a scraper and learn how to scrape the teeth....Omaha Vet 1-800-367-4444 has dental scrapers... that you must do every other month.
If you don't keep the teeth clean, they will develop periodontal disease...like the dentist says...just floss the ones you want to keep.
Alex's Yorkie Care Frequently Asked Questions. Page 2.