My little boy, Bailey, gets his teeth brushed 4-5X a week. He loves his toothpaste and I think it helps to stay ahead of tartar
I have had his teeth professionally cleaned. In fact it was about a year ago and he is scheduled to go in again later this week. They do have to snooze during this procedure so I usually have them do blood work, clean out his ears, and other procedures that are traumatic for him (and me) when he is awake.
It is very important to maintain good dental hygiene for small dogs. It is preventative maintenance, like changing your oil, etc. You have your teeth cleaned at least once and hopefully 2X per year, don't you? Well, your Yorkie is no different. Pay me now or pay me later. Plus we had some aquaintances who had to have their little boy's teeth removed because they were so badly neglected and this was by age 3.

Earlier this year they had to put the little guy to sleep.

I don't think he was much more than 7 years old and I would bet it is directly related to his dental condition.
So I am looking into the OraVet to see if that is something I might want to try for a year to see if it helps more than brushing. I wasn't sure if you could brush in addition to the OraVet, but will find out.
Best Wishes from
Samc and Bailey