There are many causes of external resorption, both general and local. An alteration of the delicate balance between osteoblastic and osteoclastic action in the periodontal ligament will produce either a build-up of cementum on the root surface (hypercementosis) or its removal together with dentine, which is external resorption.
Resorption may be preceded by an increase in blood supply to an area adjacent to the root surface. The inflammatory process may be due to infection or tissue damage in the periodontal ligament, or, alternatively post-traumatic hyperplastic gingivitis and cases of epulis. It has been suggested that osteoclasts are derived from blood-borne monocytes. Inflammation increases the permeability of the associated capillary vessels, allowing the release of monocytes which then migrate towards the injured bone and/or root surface. Other causes of resorption include pressure, chemical, systemic diseases and endocrine disturbances.
Resorption may be preceded by an increase in blood supply to an area adjacent to the root surface. The inflammatory process may be due to infection or tissue damage in the periodontal ligament, or, alternatively post-traumatic hyperplastic gingivitis and cases of epulis. It has been suggested that osteoclasts are derived from blood-borne monocytes. Inflammation increases the permeability of the associated capillary vessels, allowing the release of monocytes which then migrate towards the injured bone and/or root surface. Other causes of resorption include pressure, chemical, systemic diseases and endocrine disturbances.
Six different types of external resorption have been recognised and recorded in the literature.