Fig. 2From: Classification and morphology of middle mesial canals of mandibular first molars in a southern Chinese subpopulation: a cone-beam computed tomographic studyCBCT images of the 3-2-1 root canal system type. a–c were CT images with different cross sections: a Three canals can be seen at upper 1/3 of root canal; b There were two canals at middle1/3 of root canal; c two root canals eventually fused into one apical foramen; d–f are sagittal imagesBack to article page