Endodontic Management of Failed Root Canal Treatment in Teeth With Previously Missed Canals: A Report of Two Cases With Rare Root Canal Morphology.

Teeth may exhibit a wide range of anatomical variations in their roots and root canal systems, making them challenging to treat in endodontic procedures. Generally, maxillary canines and mandibular premolars present with a single root with one canal, and variations are comparatively rare. Achieving a fluid-impervious seal in endodontic therapy requires thorough debridement and three-dimensional obturation of the root canal system, which is considered a complex micro-neurologic procedure. Clinicians may fail to achieve the successful outcome without a comprehensive understanding of the pulp chamber and root canal system anatomy. We present a report of successful management of previously failed root canal treatment of two such cases, a maxillary canine and a mandibular premolar, with a previously missed second canal due to their uncommon root canal morphological presentation. This report also comprehensively reviews the literature, focusing on the clinically significant anatomical variations and detailing techniques for the effective management of such anomalies in endodontic treatment. The review provides an in-depth explanation of each stage of treatment, including preoperative diagnosis, intraoperative identification of morphological variations, and evidence-based modern endodontic treatment approaches. Emphasis is placed on ensuring a thorough understanding of these steps to achieve successful outcomes in the management of complex cases involving root canal anatomical variations.