Dental Disease - Feline Oral Resorptive Lesions

Dental Disease - Feline Oral Resorptive Lesions

What is a feline oral resorptive lesion?


One of the more common oral abnormalities seen in veterinary practice is the feline oral resorptive lesion (FORL). Feline oral resorptive lesions have also been called cavities, caries, cervical neck lesions, external or internal root resorptions, and cervical line erosions. FORLs are usually found on the outside surface of the tooth where the gum meets the tooth surface. Although the premolars of the lower jaw are commonly affected, lesions can be found on any tooth. A majority of the cats diagnosed with FORL are over four years of age.

What causes feline oral resorptive lesions?

The exact cause is unknown, but research suggests a correlation between problems with calcium metabolism, chronic calicivirus infections, or an autoimmune response. Whatever the underlying cause, the end result is loss of enamel on the affected tooth, through a process of resorption.

How do I know if my cat has a feline oral resorptive lesion?


The resorptive lesion erodes into the sensitive underlying dentin, causing a cat to experience pain, manifested as muscular spasms or trembling of the jaw whenever the lesion is touched. Cats with FORLs may show increased salivation, oral bleeding, or difficulty eating. The lesions can often be observed on close examination or when a cat is undergoing a dental cleaning and polishing. In some cases, the FORL will be covered with inflamed gum tissues.

How are feline oral resorptive lesions treated?

The FORL can present in many stages and treatment is based on the severity of the lesion. During early or Stage 1 FORLs, a defect in the enamel is noted. The lesion is usually minimally sensitive because it has not eroded the enamel exposing the sensitive dentin. Treatment of this stage usually involves a thorough dental cleaning, polishing, and smoothing out of the defect. In Stage 2 FORLs, the lesion penetrates enamel and dentin (the tooth layer immediately underneath the enamel). These teeth may be treated with restoratives, which release fluoride ions to desensitize the exposed dentin, strengthen the enamel, and chemically bind to tooth surfaces. The long-term (greater than two years) effectiveness of restoration for Stage 2 lesions has not been proven. Restorative application to the FORL does not stop the progression or the disease. Dental radiographs are essential to determine if the lesions have entered the pulp chamber (Stage 3 FORL) requiring either root canal therapy or tooth extraction. Radiographs will also reveal whether resorption has extended into the tooth root, requiring extraction of the affected tooth. In Stage 4 FORLs, the crown has been eroded or fractured. The gum tissue grows over the root fragments leaving a painful or bleeding lesion. Treatment for Stage 4 FORLs is gingival flap surgery and extraction of the remaining tooth root fragments.

FORLs are a common condition that requires vigilance and, often, aggressive treatment to reduce the cat's pain and discomfort. Your veterinarian will outline a treatment plan that will minimize pain and suffering. 


This client information sheet is based on material written by: Ernest Ward, DVM
© Copyright 2009 Lifelearn Inc. Used and/or modified with permission under license.