Published by: Ingrid King. Last Updated on: June 28, 2023 by Crystal Uys

Veterinarian examining teeth of Persian Cat

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 in cats

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.)

Signs of tooth resorption in cats

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!)

Orange cat drooling
Image Credit: Ling Chen, Shutterstock

Diagnosis of tooth resorption in cats

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 in cats

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.

Cream colored Maine Coon cat getting teeth brushes by owner
Image Credit: Nils Jacobi, Shutterstock

My personal experience on cats 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.

Featured Image Credit: dididesign021, Shutterstock

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