ental Disease: Long-standing claims that cats have less dental disease when they are fed dry food versus canned food are grossly overrated, inaccurate, and are not supported by recent studies. This frequently stated (among veterinarians and lay people) myth continues to harm cats by perpetuating the idea that their food bowls need to be filled up with an unhealthy diet in order to keep their teeth clean.
The idea that dry food promotes dental health makes about as much sense as the idea that crunchy cookies would promote dental health in a human.
First, dry food is hard, but brittle, and merely shatters with little to no abrasive effect on the teeth. Second, a cat's jaws and teeth are designed for shearing and tearing meat - not biting down on dry kibble. Third, many cats swallow the majority of their dry food whole.