Many pet owners and veterinarians believe that canned food is worse for cat and dog oral health than typical dry pet foods. In fact, I'll be honest and say that I too used to believe that. However, since I joined PetSmart earlier this year, I have been doing a lot of research on pet nutrition and oral health and I have yet to find a scientific study that supports the notion that canned food is worse than regular dry kibble for dental health.
In one study, oral health assessments were conducted for over 1300 dogs and only a few apparent differences were found in several key areas between dogs fed dry food only and those fed non-dry food only (Harvey et al., 1996). That being said, oral health is very important to your pet's overall wellbeing, so consult your vet if you are worried about the health of your cat's or dog's teeth or gums. And remember, while there may not be a difference between regular dry kibble and canned foods in regards to causing tooth decay, certain kibble formulations have been shown to improve oral health in several studies and clinical trials. Most of these foods reference oral health in their name. It's best to work with your vet to find the right oral formula, or look for one with the VOHC (Veterinary Oral Health Council) seal.
There may be several other good reasons to consider canned food. For example, when fed appropriately, foods with high moisture contents like canned foods may lead to weight loss by reducing calorie intake. Additionally, cats eating canned foods appear to be less likely to develop serious lower urinary tract conditions such as urethral obstruction. This reduction in risk may be due to the increased water consumption by cats eating canned vs. dry food. Again, consult your vet to determine the ideal nutrition for your pet if you are concerned about his or her health.