Not all dog foods clean your dog's teeth -- in fact, some of them can build up in his teeth and gums, creating a place for bacteria to grow and leading to oral diseases like gingivitis. Other foods, however, are formulated and even shaped to help clear plaque away from your dog's teeth and leave a cleaner mouth behind after mealtime.
The type of dog food that you give your pet has a major impact on his mouth's cleanliness. For example, wet dog foods may leave traces stuck in his teeth and around the gums. Dry dog food, on the other hand, helps sweep away plaque as your dog eats. The size and shape of dry kibbles can reduce the amount of plaque on your dog's teeth, simple because chewing up the food essentially dry-scrubs them on the surface. Other dog foods may even be formulated with chemicals like polyphosphate, which actively eliminate tartar buildup.