Tooth Resorption in Dogs

By Malcolm Weir, DVM, MSc, MPH; Lorraine Hiscox DVM FAVD Dip. AVDC; Jan Bellows, DVM, Dipl. AVDC, ABVP

What is tooth resorption?

This X-ray shows a dog's lower jaw; the large teeth are the canines. In the canine on the left, the root does not end in the same round way as the one on the right. The left root is resorbing at the root tip.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. Tooth resorption is a common oral abnormality in dogs.

There is more than one type of tooth resorption. Tooth resorption is typically categorized as internal or external, with subcategories of each. Although the premolars of the lower jaw are most affected, lesions can affect any tooth.

Tooth resorption is not typically observed with the naked eye; it is most often observed on X-ray (radiograph) examination. In fact, a study of 224 dogs, presented at a university dental service for oral care, found that more than half of the dogs (53%) showed radiographic evidence of tooth resorption. Incidence of this condition ranges from 17% to 54% of dogs.

In cases of internal tooth resorption, the root canal system will show an enlarged area with smooth and clearly defined margins. The recognition and treatment of external and internal tooth resorption in dogs is important for overall health and comfort.

What causes tooth resorption, where does it start, and how does it progress?

The exact cause of tooth resorption is unknown. Despite many studies, there is no known link to diet, vaccines, or other diseases. Whatever the underlying cause, the result is erosion of cementum and dentin that often progresses into the pulp of the affected tooth. Once lesions affect the crown of the tooth, they become accessible to infection by oral bacteria, which causes pain.

How do I know if my dog has tooth resorption?

In most cases, tooth resorption does not have outward signs. Once the sensitive dentin is exposed, tooth resorption is painful and often shows up as muscular spasms or trembling of the jaw whenever the lesion is touched. Dogs with tooth resorption may show increased drooling, oral bleeding, or difficulty eating. There may also be fractured teeth due to a loss of structure of the crown.

How is tooth resorption treated?

Tooth resorption is believed to be progressive and can present itself in many stages. Once the resorption has eroded the tooth crown, or if there is significant root resorption such that the stability of the tooth is in question, then extraction of the tooth is necessary.

Your veterinarian will outline a treatment plan that will minimize pain and suffering for your dog. Treatment options include:

  • Watchful waiting. When the lesions are early and the tooth crown is not affected, your veterinarian may recommend regular follow-up visits to determine if/when some form of intervention is required.
  • Extraction. When the tooth resorption has extended into the oral cavity, causing painful inflammation within the tooth crown, your veterinarian will recommend removing the affected tooth or teeth.
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