Sara Kim, D.M.D.
External and Internal Root Resorption: Etiology, Diagnoses, and Treatment
Amy Dukoff

Sara Kim

EXTERNAL ROOT resorption occurs more frequently than internal root resorption and is commonly misdiagnosed as internal root resorption. External root resorption is caused by an injury to the external root surface. After an injury such as concussion or subluxation, cementum can be damaged, resulting in a localized inflammatory response and area of resorption. In about two weeks, the periodontium and root surface should repair spontaneously, and in that case no treatment is needed. With severe injuries, such as intrusion or avulsion (especially when implantation is delayed more than 60 to 90 minutes), active external inflammation can persist and histologically there will be multinucleated osteoclasts resorbing the dentin of the root. Seven to ten days after the injury, it is recommended to treat the tooth endodontically by placing calcium hydroxide in the canals long-term and replacing the calcium hydroxide in one month and then at three-month intervals until the resorptive process ends. The high pH of the calcium hydroxide seems to permeate through the dentinal tubules thus killing bacteria and neutralizing endotoxin, which stimulates inflammation. If bacteria are thought to originate in the sulcus of the tooth (totally external), a vitality test will respond positively, but in cases where infected pulp causes external root resorption usually in the apical or lateral aspects, a vitality test can be negative.
     The cause of internal root resorption is unclear, but trauma and the extreme heat produced when using a high-speed drill without water have been suggested. Histologically, there is normal pulp tissue transforming into granulation tissue with giant cells resorbing the dentinal wall, and resorption will only occur if the odontoblastic layer and predentin are lost or altered. Internal root resorption usually contains some vital pulp and gives a positive vitality test; however, since necrotic pulp tissue is usually found coronal to the active resorbing cells which are more apical, the tooth can sometimes test negative. Internal root resorption resolves with root canal treatment because the resorbing cells will no longer have the blood supply to survive. In cases where internal root resorption causes buccal or lingual perforation, mineral trioxide aggregate (MTA) can be used to repair the site.

Figure 1
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FIGURE 1: Pre-op radiograph. Figure 2: Post-op radiograph.


November - December 2008


Essential Dental Seminars

When hunting for calcified canals or MB2’s, it is a good idea to clamp the rubber dam on the tooth behind and drag it to the tooth in front if possible. This way, the clamp doesn’t obscure your view of the external tooth anatomy, which is necessary to achieve the proper angulation of excavation and avoid a perforation.
Doug Kase

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