Tooth Resorption in Cats

What is tooth resorption?

Tooth resorption is a process by which the dentin (a hard tissue that lies beneath the enamel of the tooth) erodes and eventually becomes irreversibly destroyed. Over time, all areas of an affected tooth may become involved. In the past, tooth resorption was referred to as feline oral resorptive lesions (FORLs), feline odontoclastic resorptions, cavities, caries, cervical neck lesions, external or internal root resorptions, and cervical line erosions.

The most affected teeth are the premolars of the lower jaws (specifically the third premolars). 

What causes tooth resorption?

The exact cause of tooth resorption is unknown at this time. Tooth resorption in cats refers to a specific and painful condition. Undetermined genetic predispositions may occur.

Are there different types of tooth resorption?

X-ray of a cat's jaw that shows a tooth undergoing resorption. Part of the root is disintegrating.Tooth resorption in cats is divided into specific types:

With type 1 tooth resorption, there is destruction of the crown but the root retains a normal appearance with an easily visible periodontal ligament.

With type 2 tooth resorption,  the root appears to be disintegrating and is not distinct from bone. This is referred to as replacement resorption.

Teeth can also be classified as being type 3 tooth resorption, meaning they show features of both type 1 and type 2. 

While the cause for tooth resorption remains unknown, type 1 tooth resorption has been linked to periodontal disease. Whatever the underlying cause, the result is loss of the outer hard tissue of the tooth (enamel, cementum, and dentin). Both types of lesions can affect the crown of the tooth as well as the root. Lesions that affect the tooth crown are very painful and require treatment.

How do I know if my cat has tooth resorption?

A cat's tooth showing the subtle signs of tooth resorption that may be seen on a physical exam.Once the sensitive dentin is exposed, tooth resorption is painful and manifests as muscular spasms or trembling of the jaw whenever the lesion is touched.

If your cat has advanced tooth resorption, she may show increased salivation, oral bleeding, or difficulty eating. Many times, no obvious signs are seen, as cats are good at hiding pain.  Without clinical screening in an anesthetized cat, tooth resorption will go undetected, and the cat will be in pain in silence.

How is tooth resorption treated?

Treatment is guided by the type of  tooth resorption. Crown amputation or tooth extraction are required. Diligent dental hygiene is the most effective aftercare. However, because the exact cause is unknown, cats with diagnosed resorptive lesions will often develop others and need these teeth extracted at further dental treatments.