Veterinary clinical experience, over the last several years, have shown that there is no difference between feeding wet food or dry food and dental disease. It is a myth that feeding dry food will protect a pets teeth against dental disease.
Several references on diet and dental disease, in Small Animal Clinical Nutrition, the authors state, "Although consumption of soft foods may promote plaque accumulation, the general belief that dry foods provide significant oral cleansing should be regarded with skepticism. A moist food may perform similarly to a typical dry food in affecting plaque, stain and calculus accumulation. Typical dry dog and cat foods contribute little dental cleansing."
In the Journal of Veterinary Dentistry the author states that "In a large survey, dogs consuming dry food alone did not consistently demonstrate improved periodontal health when compared with dogs eating moist foods." Interestingly, my clients who feed their pets raw foods plus meaty bones for chewing report the least amount of dental disease, many of these pets do not always require an annual dental cleaning.
The speed with which dental disease occurs seems to be breed or size related in dogs: most large breed dogs do not need their teeth cleaned as often as their smaller counterparts. New recommendations on feeding cats encourage wet food to increase water consumption and decrease the chance of diseases such as diabetes, as canned food most closely mimics the natural diet of cats.
The best thing you can do to control dental disease is to regularly brush your pet's teeth and have a professional cleaning whenever needed.