Figure 1. Reference planes and landmarks used in the study. ^A, Frontal view of the craniofacial bone. ^B, Lateral view of the craniofacial bone. ^{C, D}, Setting of the three perpendicular reference planes. The red plane represents the sagittal plane (sag), the blue one represents the axial plane (axi), and the green one represents the coronal plane (cor). Terms and definitions are listed in Table 1.