Feline Tooth Resorption

Information below intended for veterinarians.

An Update on Feline Tooth Resorption

Tooth resorption is a pathologic process that results in the loss of tooth structure. It generally begins below the gum line with resorption of the cementum or more rarely at or above the gum line with resorption of enamel. Tooth resorption occurs in dogs and cats, though it is more commonly recognized in cats.

In cats, tooth resorption is one of the most commonly identified oral diseases with various studies reporting an incidence of up to 75% in domestic adult cats.

Tooth resorption has been referred to by many names including: cervical line lesions, neck lesions, cat caries and feline odontoclastic resorptive lesions. Currently the American Veterinary Dental College advises the use of the term "tooth resorption”, abbreviated TR, to describe this syndrome in dogs and cats. TR has been identified in cats dating back to the 1300’s with an increased incidence reported since the 1970’s. Although there has been extensive research and many theories proposed, to date there is no proven etiology.

Clinical signs of TR may be discovered incidentally on oral exam, as cats are masters at hiding discomfort. The cats that do exhibit signs may not do so until the process is very advanced. Clinical signs may include decreased appetite, drooling, pawing at their face, “chattering”, and reluctance to eat hard kibble. The mandibular 3rd premolar is considered the “sentinel” for TR in the cat.

Typically, if TR is discovered in one tooth . . . there will be other teeth also affected within the mouth. Therefore, full mouth intra oral radiographs are recommended on each patient.

Tooth resorption begins when odontoclasts from the periodontal ligament begin resorbing the root surface cementum and then progresses into the underlying dentin. Resorption may then extend apically as well as coronally and may even occur on the same tooth on different root surfaces.

TR that occurs at the gingival margin (previously called “neck lesions”) may be exposed to bacteria in the mouth resulting in periodontal inflammation. This may be manifested clinically as highly vascular and inflamed granulation tissue covering the defect on the tooth. These defects are painful and bleed easily. This type of resorption is generally accompanied by resorption of the adjacent alveolar bone. The roots below the lesion may appear radiographically normal with a normal periodontal ligament space. This type of TR is classified as Type I. (See photograph and radiograph at right).


Feline Tooth Resorption
Feline tooth resorption x-ray
Photograph Type I
Intraoral Radiograph Type I


Tooth resorption is classified as Type II when a grossly appearing “normal” tooth has radiographic evidence of ankylosis and replacement resorption with loss of the periodontal ligament space.


Feline tooth resorption
Feline tooth resorption x-ray
Photograph Type II
Intraoral Radiograph Type II


Some patients may have teeth that exhibit both Type I and Type II resorption.

Historically, attempts to save teeth with restorations proved to be unsuccessful long term. Complete extraction is currently the treatment of choice for TR. Even those teeth without any orally exposed lesions should be extracted as the resorption process will progress, subsequently resulting in exposed oral lesions causing pain and discomfort for the cat.

After obtaining radiographs, extractions should be performed surgically with full thickness mucogingival flaps. This allows for complete removal of tooth structure, alveoloplasty, and closure of the extraction site. Atomization (root pulverization with a high-speed bur) is not recommended due to the potential complications such as, incomplete removal of the root, excessive bone removal, damage to neurovascular structures and displacement of root tips into the mandibular canal, nasal passage or maxillary sinus.

Postoperative radiographs should always be obtained
after extraction to insure complete removal of the roots.

Teeth with Type II lesions where there is advanced resorption, ankylosis and no discernible periodontal ligament space may be treated in selective cases by crown amputation and intentional root retention. It is thought that the remaining root structure continues the resorption ankylosis process until root replacement resorption is complete. Performing crown amputation procedures on patients with periodontal disease or stomatitis is considered inappropriate and may result in incomplete resorption of the roots and result in chronic pain and discomfort for the patient.

In conclusion, tooth resorption is a commonly identified oral disease in cats causing destruction of tooth substance which results in pain and discomfort to our feline patients. The etiology is unknown though many theories have been proposed. The current treatment of choice is complete surgical extraction. A thorough intra oral exam utilizing a dental explorer and intra oral radiographs are recommended annually for all adult cats.


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