What is external resorption?

External resorption occurs when the root surface of a tooth becomes inflamed and the body attacks the root, causing it to be destroyed or dissolved. There are two types of resorption: internal and external. External resorption differs from internal in that tooth destruction begins on the outer surface of the tooth, also known as the cementum, and then travels through the tooth tissue to the root. This type of resorption is usually much more serious and almost always leads to tooth extraction.

The cause of external resorption is sometimes unclear, but there are many situations that can cause a tooth root to dissolve. Pressure from another tooth or orthodontic materials, for example, can cause trauma to the outside of the tooth, which is sometimes seen in children who have impacted wisdom teeth that are pressing on an emerging tooth. Bacteria that cause infection or inflammation can also cause the body to attack and destroy the tooth. Also, trauma to the tooth caused by a violent blow can lead to this condition: the body tries to dissolve the broken parts of the tooth, which can end in complete resorption of the root.

Once trauma has occurred to the tooth, osteoclasts, a type of cell that destroys bone tissue, attach to the root surface and begin to dissolve the outer layer of the tooth root. This process continues down to the inner root of the tooth, destroying blood vessels and nerve tissue and causing the tooth crown to become loose and unstable. Tooth resorption occurs if the entire tooth is affected, including the bone, ligament, and crown.

Sometimes the space left by dissolved root tissue will be replaced by bone. The bone adheres to the tooth in a process called ankylosis. However, the bone will begin to convert the other surrounding dental tissue to bone, which can cause even more serious dental problems.

A tooth affected by external resorption almost always needs to be extracted because the dissolution process can also spread to other surrounding teeth; However, an internally resorbed tooth can be saved by root canal treatment. Once the tooth is extracted, an implant will be placed. A person with symptoms of external resorption should immediately contact a dentist to learn more about external resorption and to determine a course of treatment.

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