According to the American Association of Endodontics in 1944, resorption is defined as “A condition associated with either a physiologic or a pathologic process resulting in the loss of dentin, cementum or bone.” Root-resorption is the resorption affecting the cementum or dentin of the root of tooth. Resorption is a perplexing problem for all dental practitioners. The occurrence of resorption can not be predicted, it can be identified radiographically. But even this diagnostic tool has limitation because resorption on buccal or lingual surface of tooth usually can not be seen until 20–40% of the tooth structure has been demineralized. Since the etiological factors, diagnosis, treatment and prognosis differ for the various types of resorption defects, the practitioners must be able to diagnose resorption radiographically or clinically, distinguish internal from external resorption and instigate appropriate treatment to stop the progress of the resorption process.