Figure 4. Demonstrations of the lines of traction force by cone-beam computed tomography (CBCT) images. A, Right sagittal view; B, left sagittal biew; C, coronal view. In right and left sagittal views of the CBCT scan, the angle between the lines of traction from the helix to the minscrews relative to the occlusal plane clearly indicate the apical direction of distal driving force. The coronal view shows the divergent distal driving force as the expansion component of applied force.