The final success of root canal treatment depends on the correct diagnosis of the endodontic disease and the knowledge of pulp chamber and root canal anatomy. The anatomy of the roots is always complex because of its variability; there are secondary canals, apical deltas, anastomoses, isthmuses and apical curvatures. The root canal treatment becomes more and more difficult when clinicians have to treat teeth with anatomical anomalies. This article reports two infrequent cases of mandibular anterior teeth with root anomalies. The first one is a mandibular incisor with three root canals treated in one visit through an endodontic laserassisted treatment to enhance the decontamination of root canals. The second one is a clinical case of a mandibular canine with two roots and two canals treated with conventional root canal treatment and subsequently rehabilitated with a fibre post and complete metal-ceramic crown. The aim of this article is to point out the importance of the correct study of the root anatomy before root canal treatment, based on accurate radiographic evaluation. Parole chiave: anatomical anomalies, diagnosis in endodontics, mandibular canine, mandibular incisors, root canal treatment