Previously known as ‘feline odontoclastic resorptive lesions (FORLs) or ‘neck lesions’, tooth resorption is one of the most prevelant oral diseases found in cats. It’s thought that up to two-thirds of the cat population over the age of five years are affected by the condition, and it is one of the most common reasons for tooth loss and tooth extraction in cats.
The tooth is comprised of two main parts, the crown (which is above the gumline) and the root (which is below the gumline and attached within the socket of the jaw bone). The tooth crown is covered by enamel and the root is covered by cementum. Beneath the enamel and cementum is dentin, a thick layer that forms the major portion of the tooth. Dentin is a permeable layer, made up of microscopic tubules which are capable of sensing pain. Beneath the dentin lies the pulp cavity, the space which houses the larger tooth nerves and blood vessels.
Tooth resorption in cats is a painful, progressive condition where the hard tissues of the tooth are destroyed, eventually resuting in loss of the tooth crown and replacment of the root by bone-like tissue. The process begins on the root cementum, with resorption progressing either deeper into the root, into the tooth crown or simultaneously affecting both areas. Once the resorption process reaches the tooth crown it typically undermines the hard enamel, creating a pink discoloration and eventually developing into a cavity-like indentation near the gumlime. When exposed to the mouth these lesions become inflammed, and in some instances the gum tissue will overgrow the defect. The lesions often bleed easily and are painful to the touch. Many cats with tooth resorption will also have concurrent periodontal disease. Though numerous studies have been performed in an attempt to better understand tooth resorption, a specific cause has not yet been identified.
Symptoms of tooth resorption may include pain when eating, changes in chewing behavior, drooling, jaw chattering, tooth grinding and behavior changes Some cats will show no obvious outward symptoms of pain, as it can be in their nature to hide signs of discomfort.
The use of whole-mouth dental radiographs (xrays) is imperative for the accurate diagnosis and treatment of tooth resorption. Radiographs will identify lesions localized to the root surface, as well as delineating the extent of the lesions on the crown of the tooth. Advanced lesions above the gumline can usually be seen on visual inspection, and early lesions at the gumline can often be found by the use of a fine tactile periodontal probe on an anesthetized oral examination.
Treatment for tooth resorption is based on the evaluation of the dental radiographs. Complete extraction of the tooth is the treatment of choice for teeth that have detectable lesions on, or near, the crowns. In some cases, when teeth have both crown resorption and advanced resorption of the roots, subgingival amputation of the crown (intentional coronectomy) may be performed. Closure of the gingiva at the surgery site should always be performed. Tooth resorption that is limited to the deeper root surfaces only can be monitored for progression.
Microscopic studies support the finding that cats affected with tooth resorption are likely to develop additional lesions on new teeth in the future. Thus, semiannual dental examinations are recommended for all cats with a previous diagnosis of tooth resorption. Dental radiographs should be repeated annually, or more frequently, if indicated by the oral examination.
Author: Kristin Walker, DVM, DAVDC, WestVet