External cervical resorption: a review

External cervical resorption (ECR) is the loss of dental hard tissue as a result of odontoclastic action; it usually begins on the cervical region of the root surface of the teeth. The etiology, predisposing factors, diagnosis, and management of ECR are reviewed. Effective management and appropriate treatment can only be carried out if the true nature and exact location of the ECR lesion are known. The role of cone beam computed tomography as a diagnostic adjunct for the management of ECR is also reviewed.