Cat Dental Problems: Resorptive Lesions
Drs. Foster & Smith Educational Staff

Resorptive Lesions
Cats are prone to a serious and very painful dental disease called "tooth resorption." Various studies have found 28-67% of cats have tooth resorption. Tooth resorption is the most common cause of tooth loss in cats.

Tooth resorption results in the loss of tooth structure, starting with the outer enamel surface, usually at or below the gum line. The lesions, which are NOT cavities, begin as a loss of tooth enamel and can eventually spread to the dentin and then the pulp canal, which contains the blood vessels and nerves to the tooth. Sometimes, the entire crown of the tooth may be missing.

Tooth resorption is progressive and may be singular or multiple and on either side of the tooth. Some lesions are readily apparent and others may be hidden under areas of plaque or swollen gums. This is why a cat needs to be anesthetized to determine if such lesions are present: the entire surface of each tooth must be examined.

The cause of resorptive lesions is unknown. One theory is that the inflammation caused by plaque may stimulate cells called "odontoclasts," which eat away at the enamel of the tooth. Other possible causes include autoimmune disorders, changes in pH in the mouth, viral diseases, or a problem with calcium metabolism.

Resorptive lesions that have eroded through the enamel may be very painful. Cats with oral pain may appear irritable or aggressive, have a change in appetite or food preference, and may have difficulty chewing and eating (food falls from their mouth). Cats with resorptive lesions may show pain when their jaws are touched and may also have increased salivation or oral bleeding.

STAGE I: Loss of enamel only, extending
     less than 0.5 mm into the tooth.
STAGE II: Lesion extends into the dentin.
STAGE III: Lesion extends into the pulp
     canal, but good tooth structure remains.
STAGE IV: Lesion extends into the pulp canal
     and there is extensive loss of tooth
     structure.
STAGE V: Crown of tooth is missing, but
     roots are present.
Resorptive Lesions
Dental radiographs are essential in diagnosing this condition and evaluating the extent of disease. Resorption lesions are graded according to the amount of tooth that is lost (see right).

Depending upon the stage of resorption, the entire tooth with the roots may be extracted, or only a portion of the tooth is removed. Cats who have a history of tooth resorption should have a prophylaxis (professional dental cleaning) every six months. Good home dental care is important for cats with tooth resorption.