Extracanal invasive root resorption: a perplexing oddity

Extracanal invasive resorption originates in the periodontal ligament, making it difficult to determine during treatment whether all resorption cells have been eliminated. Consequently, periodontal defects and recurrence of the process are quite common. This process can occur supraosseously or subosseously and treatment may or may not include endodontic therapy. The pathogenesis, diagnosis, and treatment modalities are presented along with a clinical case with an 18-month follow-up as an example of the challenges associated with treatment of this lesion.