Tooth Resorption

Laurie Anne Walden, DVM

Radiograph of 3 cat teeth undergoing resorption. Tooth on the far right is in an advanced stage of resorption. Image by Rebecca Johnson, DVM.

Tooth resorption is a potentially painful dental problem that is common in adult cats and occasionally affects dogs. The condition gets worse over time and can involve many teeth or only a single tooth root. Animals with tooth resorption and mouth pain might not have any obvious symptoms.
 
Description
Tooth resorption is the process of tooth breakdown and reabsorption by the body. Tooth root resorption is normal in baby teeth. Think of how a baby tooth looks after it falls out: it has a jagged edge instead of long roots. Its roots were resorbed as the permanent tooth moved into its place. If its roots had not been resorbed, the baby tooth would stay in the mouth instead of falling out to make room for the permanent tooth.
 
For reasons that are still unclear, many cats experience abnormal resorption of adult teeth. Resorption of adult teeth can affect only the roots or both the roots and the crown (the visible part of the tooth above the gumline). Resorption is not the same as cavities, which are rare in cats and dogs.
 
Tooth resorption in adult teeth usually begins with the loss of a small amount of the hard outer tooth surface at or below the gumline. Resorption progresses until it reaches the soft pulp at the center of the tooth. Another type of tooth resorption begins in the pulp and works its way outward.[1] The process involves bone remodeling along with tooth destruction, and in the final stage the root mostly disappears and is replaced with bone.[2]
 
Inflammation plays a part in tooth resorption, although whether inflammation causes resorption or resorption causes inflammation is not known.[3] In any case, many cats with tooth resorption also have gingivitis or more severe inflammation in the mouth. Whether tooth resorption is painful depends on the degree of inflammation, location of the resorbed area (above or below the gumline), stage of resorption, and presence of other problems like infection.
 
Symptoms
Tooth resorption is very often a hidden condition that isn’t found until a cat is under anesthesia for a dental procedure and has dental radiographs (x-ray images) taken. Cats and dogs can have mouth pain with very subtle or no symptoms of discomfort. Gingivitis is sometimes a sign of underlying tooth resorption.
 
Animals with tooth resorption might have these symptoms:

• No symptoms (common)
• Red, swollen, or bleeding gums
• Swallowing food without chewing
• Preferring soft food
• Eating less
• Drooling more than usual

 
Diagnosis
Tooth resorption is diagnosed with dental imaging (radiographs or computed tomography) and a full oral examination that includes probing around all sides of the teeth. These procedures require general anesthesia or at least deep sedation. Examination of a cooperative awake patient can reveal resorption that affects the crown, but it won’t show resorption of tooth roots.
 
Treatment
Currently the only effective treatment for tooth resorption is extraction of the affected teeth. If the tooth roots have already been replaced by bone, only the crown of the tooth might need to be removed. Decisions about whether to extract, when to extract, and how much tooth to extract are based on how the teeth look on radiographs and whether the condition is likely to be painful.[3] Medical treatments like antibiotics and steroids don’t stop tooth resorption.
 
Tooth resorption can’t be prevented because the cause isn’t known.[2] The best way to catch the problem is with regular dental care, including an oral examination and radiographs under anesthesia as recommended by a veterinarian.
 
References
1. AVDC nomenclature: tooth resorption. American Veterinary Dental College website. https://avdc.org/avdc-nomenclature/. Accessed January 31, 2020.
2. Reiter AM. Tooth resorption in small animals. Merck Veterinary Manual website. https://www.merckvetmanual.com/digestive-system/dentistry/tooth-resorption-in-small-animals. Updated May 2014. Accessed January 31, 2020.
3. Smith MM. Tooth resorption in cats: don’t think you know; know you know! In: VMX 2020 Proceedings: Small Animal & Exotics, Book 1. Orlando, FL: North American Veterinary Community; 2020.

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