External apical root resorption caused by orthodontic treatment: a review of the literature.

External apical root resorption is a common consequence of orthodontic treatment. A number of treatment-related factors have been implicated in the pathogenesis of root resorption in orthodontic patients; however recent evidence suggests that genetic factors also play a major role in the development of this condition. Herein, we review prevalence, diagnosis and aetiology of root resorption with a particular emphasis on the effect of genetic variation and orthodontic forces, as well as discuss effective prevention strategies.