Tooth resorption is a process by which all or part of a tooth structure is lost due to activation of the body's innate capacity to remove mineralized tissue, as mediated via cells such as osteoclasts. Types include external resorption and internal resorption. It can be due to trauma, infection, or hyperplasia.
Internal resorption is an unusual condition where the dentin and pulpal walls begin to resorb centrally within the root canal. The first evidence of the lesion may be the appearance of a pink-hued area on the crown of the tooth; the hyperplastic, vascular pulp tissue filling in the resorbed areas. This condition is referred to as a pink tooth of Mummery, after the 19th century anatomist James Howard Mummery.
The cause can sometimes be attributed to trauma to the tooth, but other times there is no known etiology. If the condition is discovered before perforation of the crown or root has occurred, endodontic therapy (root canal therapy) may be carried out with the expectation of a fairly high success rate.
The fact remains that for many afflicted by internal resorption, the cause is actually unknown as it cannot be tied to a specific injury or traumatic incident. This has become so prevalent that the Internal Resorption Research Project has been created to anonymously collect data from these individuals to determine if there are any common threads or trends that may help determine the cause.
In dentistry, external resorption, or root resorption, is the breakdown or destruction and subsequent loss of the root structure of a tooth. This is caused by living body cells attacking part of the tooth. Severe root resorption is very difficult to treat and often requires the extraction of teeth.
Root resorption occurs as a result of differentiation of macrophages into odontoblasts (perhaps odontoclasts?) in surrounding tissue which, if in close proximity to the root surface will resorb the root surface cementum and underlying root dentin. This can vary in severity from evidence of microscopic pits in the root surface to complete devastation of the root surface.
Deciduous root resorption is a natural process which allows exfoliation of the primary teeth to make way for the secondary teeth. It is caused by osteoclast differentiation due to pressure exerted by the erupting permanent tooth.
Root resorption of secondary teeth can occur as a result of pressure on the root surface. This can be from trauma, ectopic teeth erupting in the path of the root; chronic inflammation; excessive occlusal loading; trauma; improper reimplantation; aggressive tumors, cysts, and/or other growths; and/or unknown causes. The most common cause in Western society is orthodontic forces.
Roots of teeth are covered with cementum, a structure that resembles bone. However, cementum is more resistant to resorption than bone. There are a number of theories as to why this is the case. The most common hypothesis is that because cementum is harder and more mineralized than bone, and has anti-angiogenic properties, blood vessels are inhibited from forming adjacent to cementum, which in turn prevents access to osteoclasts.
- Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001.
- Internal Resorption Research Project website http://internalresorption.com accessed February 17, 2014.