Tooth Resorption in Cats: Signs, Pain, and Treatment

What tooth resorption is

A tooth has a hard outer layer of enamel and, beneath it, a layer called dentin. In tooth resorption, cells called odontoclasts become active and break down the hard tissue of the tooth. The process usually starts on the root surface and spreads through the dentin. Over time, it can affect the whole tooth, from the root to the crown, and the damage cannot be repaired.

You may also see it called feline odontoclastic resorptive lesions, or FORL, neck lesions, or cervical line lesions. The lower third premolars, teeth near the back of the lower jaw, are the ones most often affected, but any tooth can be involved.

When the damage stays inside the root, it may not hurt. Once it reaches the crown and the sensitive inner part of the tooth is exposed to the mouth, it becomes painful. Eventually the weakened crown can break off and leave the root behind.

How common it is

Tooth resorption is very common. Studies report it in roughly 20 to 60 percent of cats, and it becomes more likely with age. The Cornell Feline Health Center estimates that about three-quarters of cats aged five and older are affected. Some studies also suggest purebred cats are affected more often.

Many lesions are hidden. In one study, X-rays found lesions in almost half of the cats that had no visible lesion in the mouth. A cat that has tooth resorption in one tooth is also likely to develop it in others.

What causes it

The exact cause is unknown. Researchers have looked at several possible factors, including inflammation of the gums and the tissues around the tooth, diet, and too much vitamin D in food, but none has been proven. One type of resorption is linked to periodontal disease. Many cases have no clear trigger, and for these there is currently no known way to prevent the condition or stop it from progressing.

Signs to watch for

Cats are very good at hiding pain, and many cats with tooth resorption show no obvious signs. When signs do appear, they can be subtle.

• Jaw chattering or trembling, especially when the tooth is touched
• Dropping food or letting food fall out of the mouth
• Chewing on one side of the mouth, or tilting the head while eating
• Swallowing food without chewing
• A new preference for soft food, or trouble eating dry food
• Drooling
• Bleeding from the mouth
• Not wanting the mouth or face touched
• Eating less, or refusing food, especially once a crown breaks
• Red gum tissue that seems to grow into a tooth

Many of these signs also appear with other mouth problems, such as gum disease and stomatitis. A vet exam is the only way to tell them apart.

How vets diagnose it

Your vet may see a small hole in a tooth near the gumline, or red gum tissue growing over a defect. A cat may flinch or chatter its jaw when the area is touched. But a look in the mouth of an awake cat only shows late lesions that have reached the crown.

A full diagnosis needs a dental exam under general anesthesia. Blood tests beforehand help check that anesthesia is safe. Once the cat is asleep, the vet cleans the teeth and checks each one with a probe. Full-mouth dental X-rays are essential, because much of the damage happens below the gumline, in the roots.

The X-rays also show which type of resorption is present, and that decides the treatment.

• Type 1. The crown is damaged, but the root still looks like a normal root on X-ray, with the thin space between the root and the bone still visible. This type is linked to inflammation.
• Type 2. The root is gradually replaced by bone and becomes hard to tell apart from the jaw.
• Type 3. Different parts of the same tooth show features of both types.

If your cat finds vet visits stressful, our guide on taking your cat to the vet has tips that can help.

Treatment

Fillings do not work for tooth resorption. Studies have shown that the resorption continues under the filling and the filling is lost. Treatment is therefore removal of the painful tooth or tooth parts.

• For type 1 lesions, the whole tooth, crown and roots, is extracted.
• For many type 2 lesions, the vet removes the crown and leaves the root remnants, which are already being replaced by bone. This is called crown amputation. It is only suitable when X-rays confirm type 2 and there is no infection or inflammation around the tooth.
• Lesions that stay within the root and are not exposed to the mouth may sometimes be monitored with repeat X-rays instead.

Teeth affected by resorption can be difficult to extract, and follow-up X-rays help confirm that no painful fragments are left behind. Because the disease keeps progressing, many veterinary dentists recommend treating every affected tooth, even when the damage is still mild.

Recovery after dental surgery

Your vet will send you home with clear instructions. Pain relief is common, and it is important to give every dose as directed rather than stopping when your cat seems better. Soft food, such as wet food or kibble soaked in water, is usually advised for several days. Many vets schedule a recheck one to two weeks after surgery.

Owners often worry about how a cat will eat with fewer teeth. Cats adapt very well, even when many or all of their teeth are removed. Many owners notice that their cat seems happier and more active once the painful teeth are gone.

When to see a vet

Book a vet visit if you notice any of the signs above, even if your cat is still eating. Contact your vet promptly if your cat has any of these signs.

• Stops eating, or eats much less than usual
• Has bleeding from the mouth or heavy drooling
• Paws at the mouth or face
• Has swelling of the face, jaw or the area under the eye
• Has discharge from the nose or mouth, or a very bad smell from the mouth
• Hides, seems very quiet or cries out when eating

A cat that stops eating can become seriously ill, so do not wait to see whether the appetite returns. Our guide to a cat not eating explains the risks.

Checkups and prevention

Because the cause is unknown, many cases cannot be prevented. Regular dental checkups help find lesions before they become very painful. Cats that have had tooth resorption should have their mouth checked at least once a year, and vets often recommend repeat dental X-rays under anesthesia for these cats. Keeping the gums healthy may help prevent some cases. For daily tooth care at home, see Dental Care for Dogs and Cats.

Rescue cats and dental health

Many cats in rescue are adults or seniors, and their dental history is usually unknown. At Paw Squadron, every cat we rescue has a vet check and deworming. A basic checkup cannot rule out tooth resorption, though, because so much of it is hidden below the gumline. If your adopted cat drops food, chatters its jaw or chews on one side, ask your vet about a dental exam with X-rays. If you are thinking of giving an older cat a home, our guide to adopting a rescue cat covers the first steps.

For more cat health guides, browse PawPedia. If you adopted a cat from us and have questions, write to us from the Contact page.