Tooth resorption is when the body cells attack and destroy part of a tooth.
Root resorption is the breakdown or destruction of the root structure of a tooth.
This is caused by living body cells attacking part of the tooth. It can be caused from trauma, inflammation, excessive occlusal loading, aggressive growth and orthodontic forces.
When the damage extends to the whole tooth, it is called tooth resorption. Severe root resorption is very difficult to treat and often requires the extraction of tooth.
If the cells inside a tooth attack inside of the tooth – from inside it is called internal resorption.
Internal root resorption is often difficult to treat because it creates round hollow areas inside the root and root canal instruments are not designed to clean these areas out. . If found early, a tooth with internal resorption can be saved with root canal therapy.
If the the cells on the outside of a tooth attack the outside of the tooth and slowly progress inside the root, it is called external resorption
External tooth resorption is much worse and has a poorer prognosis than internal tooth resorption. In most cases, a tooth with external resorption has to eventually be extracted.