TR lesion right lower 2nd premolar and X-ray of teeth
One of the more common oral abnormalities seen in veterinary practice is the feline tooth resorption lesion (TR). Feline tooth resorption lesions have also been called cavities, caries, cervical neck lesions, external or internal root resorptions, and cervical line erosions. Other than external appearance, TRs are not the same thing as caries or cavities in people. TRs are usually found on the outside surface of the tooth where the gum meets the tooth surface. Although the first premolars of the lower jaw are most commonly affected, lesions can be found on any tooth. A majority of the cats diagnosed with TR are over four years of age.
What causes feline tooth resorption lesions?
The exact cause is unknown, but current theories have suggested a possible correlation between problems with calcium metabolism, chronic viral infections, or an autoimmune response. Genetics may play a role, as well, since certain breeds are more predisposed to this condition. Whatever the underlying cause, the end result is loss of enamel and dentin on the affected tooth, through a process of resorption.
How do I know if my cat has a feline oral resorptive lesion?
The tooth resorption 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 TRs 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 TR will be covered with inflamed gum tissues.
How are feline oral resorptive lesions treated?
The TR can present in many stages and treatment is based on the severity of the lesion. During early or Stage 1 TRs, an enamel defect 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 the defect. In Stage 2 TRs, the lesion penetrates enamel and dentin. 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 of Stage 2 lesions is uncertain. Restoration of the TR does not stop the progression or the disease, however. Dental radiographs are essential to determine if the lesions have entered the pulp chamber (Stage 3 TR) requiring either root canal therapy or tooth extraction. However, root canal therapy is generally not recommended, because the prognosis for the affected tooth is very poor. Radiographs will also reveal whether resorption has extended into the tooth root, requiring extraction of the affected tooth. In Stage 4 TRs, the crown has been eroded or fractured, and most of the hard tissue has been lost. The gum tissue often grows over the root fragments leaving a sometimes painful or bleeding lesion. Treatment for Stage 4 TRs is gingival flap surgery and extraction of the remaining tooth root fragments. Stage 5 TRs present as a non-inflamed raised area of gum tissue, and on radiographs the roots have been completely resorbed into the bone. There is no treatment needed for Stage 5 TRs, because they have ceased to be painful.
TRs are a common condition that requires vigilance and often aggressive treatment in the form of extractions to reduce the cat’s pain and discomfort. Your veterinarian will outline a treatment plan that will minimize pain and suffering.