Fig. 2. Three-dimensional orientation of tooth. A, X-axis is the line passing through mesial cementoenamel junction (M-CEJ) and distal cementoenamle junction (D-CEJ). Y-axis is the line passing through the projected distal CEJ (D-CEJ’) and cingulum point (Cingulum’) on the sagittal reference plane. B, Z-axis is the cross product of the X-axis and Y-axis.
