Yorkies do need special care taken of their teeth because they are prone to periodontal disease and tooth loss so you should brush their teeth several times a week and feed mostly kibble and not a lot of wet food that can stick to the teeth.
I give my dogs toothbrushes to chew on, I have dental wipes and I have a finger brush and several different flavors of toothpaste. It's actual fun and if you start it when they sre young they actually like it.
