teeth cleaning

How often is it necessary to have my girls' (dogs) teeth cleaned? My Sammie is 5 and her back teeth are getting yellow and have some signs of brown. ..My Collie's are still pretty white; she's 4. They both eat the same food.

[Dan Sims, DVM]

The answer is as often as needed.
The average canine needs a dental prophylaxis twice in their lifetime and some never and yet we clean some dogs teeth every year:these are usually small breed dogs.
If your Veterinarian decides a cleaning is needed discuss the use of dental xrays to assess the roots of the teeth for disease.