Root canal anatomy of mandibular second molars differs among individuals. With the aid of the latest dental technologies in endodontics, the present case report highlights the diagnostic tools required to confirm the morphology of the root canal, and the treatment of uncommon root anatomy of a single-canal single-rooted mandibular second molar. Clinicians should be aware of the various anatomic variations that each tooth may present in order to achieve a satisfactory result. Furthermore, in order to improve the quality of care delivered to their patients, practitioners must have the necessary knowledge and abilities to utilize the diagnostic and therapeutic instruments at their disposal.