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Tooth Resorption in Cats

Date Published: 06/17/2002
Date Reviewed/Revised: 06/21/2016
Photo by Dr. Jan Bellows

A common feline oral malady is tooth resorption (TR). Greater than half of all cats older than three years old will have at least one tooth affected by resorption; it affects dogs less frequently.   These tooth defects have been called cavities, neck lesions, external or internal root resorptions, feline odontoclastic resorption lesions (FORLs), and cervical line erosions.

Tooth resorptions are usually found on the outside of the tooth where the gum meets the dental surface. The lower jaw premolars are mostly affected, however tooth resorption can be found on any tooth. 

The cause is unknown, but theories supporting an autoimmune response, calicivirus, and metabolic imbalances relating to calcium regulation have been proposed.  Commonly the resorption starts at the gum line and progresses, eroding sensitive dentin.  Some affected cats show pain and jaw spasms whenever the lesion is touched. Others show increased salivation, oral bleeding, or difficulty eating. Most times it is up to the veterinarian or astute owner to diagnose tooth resorption.

Photo by Dr. Jan Bellows

There are five recognized stages of tooth resorption. Initially in stage 1 only an enamel defect is noted. The lesion is usually minimally sensitive because it has not entered the dentin. In stage 2, the lesion penetrates enamel and dentin. When resorption progresses into the pulp chamber (nerve) stage 3 has occurred.  In stage 4, large amounts of the tooth's hard structure have been destroyed. By the time stage 5 has occurred, most of the tooth has been resorbed, leaving only a bump covered by gum tissue.

Intraoral x-rays are essential to evaluate all the teeth to determine the best course of therapy. Depending on what is seen in those intraoral x-rays, treatment for tooth resorption involves either extraction of the entire tooth and roots, or a partial tooth extraction.  In cats affected by stage 5 without inflammation, treatment is not necessary.