Good question. Yorkies are known for having bad teeth (genetics) but as breeding evolves... you make be able to get a Yorkie that is not as predisposed to having bad teeth.
That said, If your Yorkie has horrible teeth, a visit to the dentist every year for cleaning/scaling/polishing would be best. Every two years if the Yorkie has good teeth bred into their lines.
Last but not least, it depends greatly on your Yorkies' oral hygiene. If you brush their teeth, you may be able to lengthen the time between visits.
PS: Feeding kibble does not help to keep teeth clean, as was previously thought.
