Mandibular first premolar with two roots and three canals.

This case report presents a relatively uncommon clinical case of a mandibular premolar with two roots and three canals. The possibility of additional root canals should be considered even in teeth with a low frequency of abnormal root canal anatomy. Sound knowledge of root canal anatomy, appropriate assessment of the pulp chamber floor, critical interpretation of radiographs and high-magnification examinations are highly desirable to achieve the best possible outcome in complicated root canal therapy.