External inflammatory resorption is one of the potential consequences of trauma to the teeth. It occurs when there has been loss of cementum due to damage to the external surface of the tooth root during trauma, plus the root canal system has become infected with bacteria. It is characterized by the radiographic appearance of loss of tooth substance with a radiolucency in the adjacent periodontal ligament and bone. The loss of cementum allows the intracanal bacteria and/or their endotoxins to reach the periodontal ligament more readily and this can lead to the development of the inflammatory resorptive process. External inflammatory resorption can ultimately lead to loss of the tooth if it is not managed in a timely manner. There are some injuries that are very likely to develop this type of resorption and a preventive approach can be adopted by commencing root canal treatment immediately as part of the emergency management of such cases. In cases where the resorptive process is already established, root canal treatment can arrest the resorption and encourage hard tissue repair. The use of a corticosteroid-antibiotic intracanal medicament has been shown to be particularly useful in the prevention and management of external inflammatory resorption. Calcium hydroxide should not be used as an immediate medicament because of its inherent toxicity and irritant properties but it is valuable as a subsequent medicament to encourage hard tissue repair where required. This review outlines the external inflammatory resorptive process and the management strategies that can be employed to prevent it from occurring, and to treat it if already present.