RESUMO
This study aims to present the management of a rare case of a separated endodontic instrument in the periradicular area. The broken instrument had penetrated within and along the mandibular canal from the periapical zone of mandibular second molar after endodontic treatment, leading to acute neurological symptoms. These subsided completely following surgical removal of the separated instrument. Because of the close anatomic relation between the second molars and the inferior alveolar nerve, careful clinical and radiographic examinations should always be performed before endodontic treatment of these teeth, so as to prevent iatrogenic injuries of the type described here. Dentists should also be aware of the anatomic characteristics of the mandibular canal (i.e., cribriform rather than solid), as well as the consequences of overinstrumentation.