Keles A, et al. – This study’s objective was to conduct a quantitative and qualitative analysis of the band–shaped isthmus area, the floor of which was in the apical third in the mesial roots of mandibular first molars using micro–computed tomography (micro–CT). Researchers reported that three– and two–dimensional analyses of the mesial roots of mandibular molars showed that band–shaped isthmuses had complex shapes.