Does Dry Food Clean the Teeth?

By Jean Hofve, DVM

Let’s get this one straight once and for all: dry food does not clean your cat’s teeth! In fact, dry food really does not benefit the cat at all. It is merely a convenience for the guardian. If you haven’t already read Why Cats Need Canned Food and 10 Reasons Why Dry Food is Bad for Dogs and Cats, start there in your quest for accurate, up-to-date information on feeding cats.

Most cats don’t consistently chew dry food; they swallow it whole. Obviously, without contacting the teeth, there is zero effect on tartar accumulation. For cats who do chew dry food, whether consistently or occasionally, there is still little or no benefit. The kibbles shatter, so contact between the kibble and the teeth occurs only at the tips of the teeth. This is certainly not enough to make a difference in the formation of tartar and plaque, which most commonly builds up along (and underneath) the gumline at the base of the teeth.

Keeping your cat’s (or dog’s) teeth and gums healthy requires a commitment on your part. Daily toothbrushing and regular veterinary cleanings are still important. The labels on even the special “tartar control” diets like Hill’s t/d and Friskies dental diet recommend these additional steps. (Of course, brushing daily with periodic cleaning by the vet are sufficient to keep the teeth healthy by themselves, without using a special diet at all!) Dental diets are very different from all other dry foods. The kibbles are very large, and have a different texture than regular dry food.

In my experience as a feline veterinarian, I’ve probably examined at least 13,000 cats’ mouths. There was no real pattern to the dental and periodontal disease I saw. If anything, tartar and gum disease seemed to be more attributable to genetics or concurrent disease (such as feline leukemia or feline AIDS) than to any particular diet. I saw beautiful and horrible mouths in cats eating wet food, dry food, raw food, and every possible combination. Many of my patients initially ate mostly or exclusively dry food; yet these cats had some of the most infected, decayed, foul-smelling mouths I saw. If there was any dietary influence at all, I’d say that raw-fed cats had better oral health than cats on any type of commercial food. However, the overall effect of diet on dental health appeared to be minimal at most.

If your vet still believes the myth of dry food and dental health (which is still actively promoted by the pet food companies despite the utter lack of scientific support for the theory), here are a few references that refute the idea:

* Logan, et al., Dental Disease, in: Hand et al., eds., Small Animal Clinical Nutrition, Fourth Edition. Topeka, KS: Mark Morris Institute, 2000, p. 487. “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. As a tooth penetrates a kibble or treat the initial contact causes the food to shatter and crumble with contact only at the coronal tip of the tooth surface…The kibble crumbles…providing little or no mechanical cleansing….” The author also reviewed two studies on cat “dental” treats which showed “no significant difference in plaque or calculus accumulation with the addition of dental treats to either a dry or a moist cat food.” Of course, this book was produced by Hill’s, so it heavily promotes t/d. However, although t/d provided a “statistically significant” improvement, when you look at the actual graphs, the difference between Dog Chow and t/d is not impressive.

* “…When comparing dry food only and non-dry food only fed dogs…there is no pattern to the trends (some teeth show an apparent protective effect from feeding dry food only, and others show the opposite — for calculus index, the trend is protective for all five teeth in dogs feed dry food only, whereas for gingival index it is the opposite, and it is mixed for attachment loss). All maxillary teeth are significantly less likely to be mobile in the dry food only group, yet the mandibular first molar tooth showed the opposite effect.” Harvey et al., Correlation of diet, other chewing activities and periodontal disease in North American client-owned dogs. J Vet Dent. 1996 Sept;13(3):101-105. Logan (above) assessed this study as follows: “In a large epidemiologic survey, dogs consuming dry food alone did not consistently demonstrate improved periodontal health when compared with dogs eating moist foods.”

* There is an excellent review of the literature by A. Watson (Diet and periodontal disease in dogs and cats. Aust Vet J. 1994;71:313-318). This study is fully of interesting historical items. For instance, one study of cat skulls found evidence of severe periodontal disease in 25% of 80 cats; 75 of the skulls dated from 1841 to 1958, and 2 were from Egypt during the time of the Pharoahs!

* According to the above review, many of the early studies showed less tartar formation with hard dry food vs the same food mixed with water, and similar results were reported in a study with canned vs dry cat foods. In 1965 a study compared feeding raw whole bovine trachea, esophagus, and attached muscle and fat, vs the same food minced. Plaque and gingival inflammation were increased with the minced diet. Even more fascinating, they tube-fed the minced food and found that plaque and gingivitis did not decrease, “showing food did not need to be present in the mouth to induce these changes.” In fact, gingivitis tended to increase when cats were tube-fed, “suggesting that even the minimal chewing required with minced food had some cleansing or protective effect.” Minced food is similar in texture to canned food.

* A couple of studies showed that *large* dry food biscuits (not kibble) actually removed tartar, which is probably the theory underlying t/d’s oversized chunks. Feeding of half an oxtail accomplished the same thing when fed weekly in another study. (I can just see it now, “Brand X’s Tartar Control Oxtails.”) The study also noted that “No harmful effects were observed from feeding oxtails to > 200 dogs for > 6 years.”

* Gorrel and Rawlings (The role of tooth-brushing and diet in the maintenance of periodontal health in dogs. J Vet Dent. 1996 Dec;13(4):139-143) state that: “In a previous study, we showed that the daily addition of an appropriately designed chew to a dry food diet is effective in reducing accumulation of dental deposits…the addition of the chew to the dry food diet also reduced the severity of gingivitis that developed, compared with the regimen of dry food diet alone.” This points out that dry food does not prevent tartar/gingivitis without additional treatment.

* Interestingly, Gorrel states in another article that “The consensus is that supragingival calculus per se is not directly involved in the etiology or pathogenesis of [periodontal] disease, and is mainly of cosmetic significance if plaque removal is adequate.” (Periodontal disease and diet; J Nutr. 1998;128:2712S-2714S.)

* A more recent review (DuPont G. Prevention of periodontal disease. Vet Clin N Amer. 1998 Sept;28(5):1129-1145) says, “In some dogs, dry kibble or fibrous diet helps slow plaque accumulation more than does soft or canned food…Other chewing behaviors may be even more important for reducing plaque than is feeding dry food.” Not exactly a ringing endorsement of dry food! He cites 2 studies showing Hill’s t/d to be effective for “decreasing plaque and calculus accumulation.”

* A review of feline neck lesions found no significant influence of diet. (Johnson N, Acquired feline oral cavity disease, Part 2: feline odontoclastic resorptive lesions. In Practice. 2000 Apr:188-197).

These studies show that dry food does not clean a pet’s teeth any better than eating pretzels cleans ours! At best, we can say that dry food tends to produce slightly less tartar than canned food. For cats, the benefits of feeding canned food far outweigh any possible dental problems that may result. After all, it is much easier for your vet to clean your cat’s teeth once a year than to treat diabetes, urinary tract problems, and other diseases that are either directly caused or aggravated by feeding dry food.

To put an even finer point on it, Australian veterinarian Tom Lonsdale did a fascinating experiment with four dogs, taking them off their raw meaty bones diet and putting them on Hill’s Science Diet to see how fast their health would go downhill. It only took 17 days to see these dogs deteriorate, and for tartar to begin visibly accumulating on their teeth.


Regular home and veterinary dental care are real keys to keeping your cat’s or dog’s teeth and gums healthy for life.



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6 comments for “Does Dry Food Clean the Teeth?

  1. jhofve77
    July 1, 2013 at 7:54 am

    No, of course it doesn’t. In my experience, genetics plays a very big role, and diet may not be able to overcome that, or as you said, whatever she experienced earlier in her life.

    My writing partner, nutritionist Dr. Celeste Yarnall, and I will be discussing raw diet, raw bones, and dental disease in far more detail in our upcoming book, Paleo Dog (Rodale Press), which will be published in 2014.

  2. mlouie
    June 22, 2013 at 9:17 am

    A raw diet doesn’t clear up oral disease 100% of the time. Our Chihuahua-mix dog lost over half her teeth to oral disease despite a raw diet, minimal vaccines and treatment by a very experienced homeopathic vet. Of course, we got her in mid-life from the shelter. If we’d had her from puppyhood, perhaps we could have had more effect with diet. We have had to do teeth cleanings 3-4x/year for her, but most of those have been anesthesia-free, except when teeth have needed extracting.

  3. jhofve77
    July 2, 2011 at 9:10 am

    Perhaps you did not see all the articles on feline nutrition on our website, in which we strongly advocate raw and homemade diets. There is also a simple “starter” recipe for people who want to make their pets’ food at home.

  4. Lois Walker
    July 1, 2011 at 6:31 pm

    You seem to have forgotten what cats in the wild eat and thrive on – have done for millenia. Freshly killed prey, muscle, fat, organs and bone. Feather and fur, most of which they throw up or poop out.

    It is nonsense to feed cats anything processed. They are all a cocktail of inappropriate ingredients, chemicals that cats in the wild never eat, and is cooked. Read about Pottenger’s cats to understand the nutritional damage caused by cooking foods for cats.

    Feed fatty meats – lots of species – a small amount of organ (5% of daily intake liver – no more, to avoid Vitamin A toxicity – and about 10% daily of edible bone. That’s about the ratio of fat, meat, organs and bone found in the natural live prey of wild species of cats. Cats and their ancestors have survived since it long after the dinosaurs on this diet. Their teeth, jaws, digestive trace are perfectly adapted to it, not mush from a can or harmful overcooked pellets.

    We need to NOT get sucked into the advertising of the multinationals that sell stuff to a gullible public, and vets should be ashamed of their ignorance of optimal nutrition for our small obligate carnivores, out cats. They, too, are bedazzled by the pet food reps, not to mention the $$$ they make from selling the stuff.

    Stop feeding your cats junk food and start feeding them what Nature designed them to eat. It’s cheaper, by the way.

  5. jhofve77
    June 29, 2011 at 8:13 pm

    Hi Dr. Cannizzaro, thanks for your great comments! I agree with you that raw food (especially with ground bone, which is definitely helpful) will solve many ills, including dental disease. I’ve also had reports that leaving raw diets partially frozen is also good at abrading calculus and stimulating the gums. I do not advocate yearly dental cleanings just to do them; but certainly an annual exam that includes a visual assessment of oral health is appropriate. I agree that in many (probably most!) cases diet and holistic therapy (including homeopathy, homotoxicology, NAET, and other modalities) can be very powerful, and I would definitely encourage folks to take advantage of that power! However, not everyone is ready to make the commitment to raw diet and the careful monitoring necessary for successful homeopathic treatment. I do advocate homemade, raw diets…but I consider it good progress if I can at least get a kitty off of dry food and onto canned, and it sets the stage for more progress later!

  6. June 18, 2011 at 5:21 am

    In my experience of nearly 20 years I must say that promoting raw diets has cleaned up the majority of dog and cat oral disease and calculus. There are some refractory cases of periodontal disease that diet has no effect. I suspect that the ground bone in raw diets may be more abrasive than canned food and perhaps help explain the differences. Oral disease and resorptive lesions can be vaccine induced and autoimmune in causation so diet may have little outward observable effect and I know nutrition in homeprepared balanced diet or raw fed balance diet of whole food is more nutritionally sound than any processed food in a can or a bag. The proof is in the pudding so to speak as our animal patients do not lie about their improvements. Thank you for your well written article and I would not agree with annual dental cleanings as they should not be necessary, often are not, and can be very hazardous in my experience. I am not advocating that a painful tooth may not have to be extracted, I am suggesting that tartar, staining, and gingivitis can successfully be treated with improving diet to the abovementioned, and homeopathic treatment to treat the underlying cause of oral disease is essential and very effective. Best and in peace, Robin L. Cannizzaro DVM, CVA

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