The presence of internal or external tooth resorption often poses both diagnostic and treatment dilemmas for the clinician. When viewed radiographically, these defects can easily be mistaken for each other; and the status of the dental pulp and its role in the resorptive process can also be mistaken, especially if no diagnostic tests are conducted. Furthermore, the actual aetiology for these tooth maladies is elusive, but its determination is essential to develop the best treatment plan for the patient. Treatment plans may include a surgical repair, root canal procedure or even extraction, depending on the nature and extent of the defect. The purpose of this article is to characterise the nature and uniqueness of these two resorptive defects and to show how contemporary treatment modalities can be used in the retention of teeth that present with these challenges. Schlagwörter: clastic-type cells, diagnosis, internal and external resorption, mineral trioxide aggregate, tooth retention