Representative three-dimensional image of mesiobuccal root reconstructed with NRecon software. The root has “confluent” canal configuration with isthmuses in the coronal and middle thirds. At the “0 mm” level, the mesiobuccal root has 1 canal space that becomes 2 canals as shown at “1 mm” and “2 mm” levels (dashed circles). The second mesiobuccal canal can be revealed with 1 mm troughing. The apical delta has 4 portals of exit (arrow).