External cervical root resorption begins at the root surface as result of odontoclastic activity in the cervical area and is progressive in character. The pulp is only affected at a later stage of the process. The aetiology and pathogenesis of external cervical root resorption is not fully understood. Possible predisposing factors are, among others, orthodontic treatment, trauma, internal bleaching, damaged cemento-enamel junction, bruxism and hypoxia. A 'pink spot' often is the first clinical sign and a two-dimensional radiograph usually presents an amorphous radiolucency with undefined borders. Cone-beam computed tomography is an emerging technique aiding the diagnosis of and prognosis and treatment plans for external root resorption. An external or internal treatment approach can be chosen, depending on the size of the defect.