Tooth resorption affects well over 50% of adult cats and close to 75% of cats five years or older. It is the most common reason for extractions. The condition is extremely painful, and it cannot always be diagnosed by a visual exam. Tooth resorption is also referred to as cervical line lesions, resorptive lesions, or feline odontoclastic resorptive lesions (FORLs).

The anatomy of tooth resorption

Each cat’s tooth has a chamber (the root canal) that contains tissue made up of blood vessels, lymphatic vessels, and nerves. This tissue is surrounded by dentin, a calcified tissue that is protected by the tooth’s enamel, and makes up the bulk of the tooth’s structure. Tooth resorption begins with a loss of tooth enamel and will eventually spread to the dentin and then the root canal, which contains the blood vessels and nerves to the tooth. Over time, all areas of an affected tooth, from root to crown, may become involved. Sometimes, the entire crown of the tooth may be missing.

Resorption is a progressive disease, and is not always obvious to the naked eye. In some cases, it looks as though gum tissue is growing over or into the tooth. There may also be a hole in the tooth, which is why the condition is something incorrectly referred to as a cavity. (Cavities in cats are extremely rare.)

Symptoms of tooth resorption

Tooth resorption is an extremely painful condition, but since cats are so good at masking pain, they may not show obvious signs unless the lesion is touched directly. Symptoms may include bad breath, drooling, bleeding from the mouth, and difficulty eating (a “messy eater” may be spilling food because it hurts to eat!)

Diagnosis of tooth resorption

While some lesions may be visible on a visual exam, diagnosis requires anesthesia and dental x-rays. A thorough dental procedure includes examination of every single tooth, probing for tooth mobility, and dental radiographs – and none of that can be done without anesthesia. 60% of the tooth is located below the gum line. Cats can’t tell us where the pain comes from. By not performing a thorough dental assessment, cats, who are masters at masking pain, will continue to suffer in silence. “In spite of claims some individuals make, it is technically impossible for anyone to perform a complete, comprehensive and thorough oral assessment on our companion animal patients without the assistance of general anesthesia,” says Dr. Thomas Chamberlain,MS, DVM, a Diplomate of the American Veterinary College of Dental Surgeons and owner of Animal Dentistry and Oral Surgery in Leesburg, VA..

Grading of tooth resorption

Tooth resorption is graded based on the extent and location of the lesions. There are five stages:

Stage 1 (TR 1): Mild dental hard tissue loss (cementum or cementum and enamel).

Stage 2 (TR 2): Moderate dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does not extend to the pulp cavity).

Stage 3 (TR 3): Deep dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth retains its integrity.

Stage 4 (TR 4): Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity. (TR4a) Crown and root are equally affected; (TR4b) Crown is more severely affected than the root; (TR4c) Root is more severely affected than the crown.

Stage 5 (TR 5): Remnants of dental hard tissue are visible only as irregular radiopacities, and gingival covering is complete.

(Source: Animal Dentistry and Oral Surgery Specialists, LLC)

Treatment of tooth resorption

Extraction is the only treatment for tooth resorption. Extraction of these lesions can be difficult, because affected teeth are fragile and often fracture during extraction. Dental radiographs are essential for extracting these teeth because they help the dentist find fractured root fragments. The entire tooth and any fragments need to be removed to avoid infection or other problems. While many general veterinary practices offer dentistry, I believe that dental procedures are best performed by a veterinary dental specialist. If you are considering having a general vet perform your cat’s dentistry, make sure you ask these 13 questions before scheduling a procedure.

Can tooth resorption be prevented?

SInce the cause of feline resorptive disease is unknown, early detection and treatment is probably the best way to help affected cats. Unfortunately, once a cat has had resorptive disease, it’s very common for other teeth to be affected.  Good dental hygiene, including brushing and feeding a species-appropriate raw or wet diet (contrary to what many cat parents still believe, dry food does not clean teeth) will certainly contribute to the overall health of your cat, even if they may not prevent resorptive disease.

My personal experience with resorptive disease

Both Allegra and Ruby have/had resorptive disease. Allegra had several teeth extracted two years ago. Ruby had all of her teeth extracted earlier this year. They are both fed a predominantly raw diet, and I brush their teeth. And while I won’t have to worry about a recurrence with Ruby, I make sure that Allegra gets regular check ups – and so far, so good.

15 Comments on Feline Tooth Resorption: A Painful Common Dental Disease

  1. My Jasper, 13 yrs old, has been diagnosed with FORL. The vet is hoping that only one tooth will need to be removed but they won’t really know until they get x-rays. Jasper had almost all of his teeth removed six years ago due to stomatitis; he has only his incisors and fangs. His gums recovered completely after the extractions and I never expected to hear the word dental applied to Jasper again. The tooth that they know is affected is a bottom fang and he has lost of few of his incisors already – not really unusual. I’m just worried about my boy – he is my baby.

  2. My male ragoll who is 7 years old had a full dental clean by the veterinarian 1year and 5 months ago. With our care club he has 1 free teeth cleaning a year. We were a few months behind because my husband is very sick and had to go Disability. His previous teeth cleaning found no issues at
    all. My regular vet did his yearly exam and just saw a little tartar build up. This was 2 weeks ago. He had his teeth cleaning today by the vet that specializes in this. She said on the discharge report that he had two pre molars with resorption lesions. She did not say what stage. I had discussed with her last night our financial situation and I could not pay for anything outside the covered teeth cleaning. I asked if she was still willing to do the cleaning knowing if he need extractions that could not be done now. I told her it would be about 9 months before we are back on better financial footing to be able to pay if any extractions were needed. I was good either way. First she no to today then she changed her mind and said yes.
    My questions are can these lesions form that quickly after the full teeth cleaning 1yr and 5 months ago. Know what do we do he can’t have another cleaning or extractions for a year.
    I guess we need to know what stage they are. All she said is they could start causing him pain. I feel so bad but we just don’t have the money right now. We went the whole year of
    2018 with no income until my husband was finally approved for disability. We had to use up our savings and maxed out all credit cards. Plus my other cat developed an eye condition and in the last 4 weeks we have been at the vet 9 times and spent close to 2000 dollars and counting.
    I am beating myself up about not be able to afford those extractions today.

  3. My tiny lion, a maine coon, who has lived with us just over a month, had 5 teeth extracted primarily because of these FORLs a few weeks ago. At 14 though, the veterinarian/dentist didn’t feel that there would be value in trying to brush the remaining 9 teeth (7 grinders, 2 canines). And the veterinary assistant said that at 14, I could probably assume it will not be necessary for another dental visit.

    It’s hard for me to tell what I should be doing. Visits every year still? (the tiny lion prefers not to travel and while I can have a traveling vet come to the house, that’s more difficult if I want a vet that can do the dentistry) What is the follow up for a cat that has had them before to a degree to cause extractions but is older?

    In the mean time, I’ve really enjoyed using your website as a reference as I gradually use the 5 weeks he’s been with us to transition him to a primarily raw diet. Thank you so much!

    • At your cat’s age, he should have check ups every six months not just for his teeth, but his general health. Since travel is stressful for him, a housecall vet can be a good option, that way, he’d only have to go to the clinic if he needs more dental work. Once a cat has lesions, it’s likely that more will develop. What your veterinary assistant told you makes absolutely no sense, because there’s no way to predict how quickly additional lesions will develop. Since we don’t know what causes FORLs, we also don’t know for sure whether brushing will prevent them, but it certainly couldn’t hurt if your cat will let you do it without stress, so I don’t agree with your vet’s statement, either. You may want to consider MaxiGuard – it’s easier than brushing, and while it doesn’t achieve quite the same as brushing, it can be very helpful in maintaining dental health: http://consciouscat.net/2016/06/09/review-maxiguard-oral-cleansing-gel/

      • I see. Thank you very much!

        I’d like to add that as this fellow is a new-to-us cat, we had chosen to get his dental repairs done at the same vet his prior owner had been taking him too, in order to expedite things. I never actually spoke to the veterinarian in person because of it so I’d like to say that maybe I misunderstood.

        BUT all things being equal, in six months I’ll ask one of the traveling vets, two in my area are capable of full dental in their mobile vehicle, to schedule an exam. I’m looking for a vet who can help me be more proactive.

        That’s what I am finding valuable about your site! It helps to anticipate my cats needs, to help me figure out things to do in ADVANCE, not just play catch up. Thank you so much again!

        And, I’ll definitely look into the maxiguard and see how it goes. My guy is pretty accommodating and while he seems to be mouth shy now, that may just be the prior issues while he is healing up. Thanks!

  4. Thanks for your post. I’m currently waiting to hear from my vet whether my sixteen-year-old cat can go through anesthesia for his reabsorptive lesions. It does not sound very clear, and I’m not sure what we’ll do yet. I think he is in pain thought it’s so hard to know with cats….

    • I’m curious, what did you ultimately do with your older cat? I’m facing the same issue with my fifteen-year-old cat. She has a mouth full of resorbing teeth and have been told by my vet that she will just have to endure it as her health is too fragile for the dental procedure. She chews on one side of her mouth.

      • Ryan, When my 14 year old had them done, there were no issues. He had good blood work before hand, and a great recovery. BUT I think I would risk the surgery regardless if it’s a grey area. You see, as a human with genetically soft teeth, I am very sensitive to how much it might hurt. The one thing I might have changed is that I would have had all teeth pulled at that point so as not to need surgery again in the future, rather than try and save the remaining teeth.

        Have you received a second opinion? I hope your little guy is okay regardless. I am so happy to see mine eating more normally, drooling less, being more active.

        Good luck!

  5. Love your site. I understand how challenging it is to deal with resorption. I have four rescue cats. One has resorption and had the majority of her teeth removed when she was three years old. The others have some form of dental issues. Your articles on brushing have been very helpful. I have tried different oral gels & sprays. Most contain mint which is off putting to my cats. Have you found any dental supplements, oral rinses, oral sprays, etc. to be helpful? >^..^<

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