Laurie Anne Walden, DVM
Deciduous (baby) teeth that don’t fall out on their own are called persistent deciduous teeth. These extra teeth can cause problems if they are not removed surgically. Persistent deciduous teeth are most often seen in small-breed dogs and are uncommon in cats.
Like most mammals, dogs have 2 sets of teeth in their lifetime. Deciduous teeth erupt when puppies are a few weeks old and are replaced by permanent teeth from about 4 to 7 months of age. Dogs have 28 deciduous teeth and 42 permanent teeth.
Deciduous teeth are able to fall out on their own because their roots gradually resorb (dissolve). Think of how children’s baby teeth look after they fall out: instead of long roots, they have jagged edges.
Resorption of deciduous tooth roots is a complex process that is triggered, at least in part, by the pressure that erupting permanent teeth put on the deciduous tooth roots. As a permanent tooth starts to push toward the surface, the root of the deciduous tooth directly above it resorbs until the deciduous tooth falls away. The permanent tooth then emerges in the space left vacant by the deciduous tooth.
Sometimes a permanent tooth isn’t in the right position under the gum, so the root of the deciduous tooth above it doesn’t resorb as it should. The permanent tooth then erupts next to the deciduous tooth, which stays in place as a persistent deciduous tooth.
A common persistent deciduous tooth in dogs is the canine tooth, which is the long, sharpish tooth next to the incisors at the front of the mouth. Dogs with a persistent deciduous canine tooth have 2 canine teeth (1 deciduous and 1 permanent) right next to each other, usually touching.
Problems Caused by Persistent Deciduous Teeth
Two teeth crammed into a space meant for 1 tooth is never good. Overcrowding from a persistent deciduous tooth leads to a number of problems:
A permanent tooth that has been displaced by a persistent deciduous tooth is positioned incorrectly within the row of teeth. Displaced permanent teeth might be angled toward the lips or the tongue. A displaced lower canine tooth can hit the roof of the mouth when the mouth is closed.
A persistent deciduous tooth is diagnosed when a deciduous tooth and the corresponding permanent tooth have both erupted but the deciduous tooth is still firmly fixed in place, not wiggly and getting ready to fall out. Dental radiographs are used to evaluate the tooth roots and look for other problems like impacted or missing teeth.
A persistent deciduous tooth needs to be surgically removed as soon as it is diagnosed. The longer it stays in the mouth, the greater the risk of problems with the permanent tooth. If a persistent deciduous tooth is removed early, the permanent tooth will most likely move into the correct position on its own as the puppy grows.
Photo by Elena Mozhvilo on Unsplash
Laurie Anne Walden, DVM
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