Fig 1.
Various horizontal reference planes in the skull model.
(A) FHP-P. (B) FHP-O. (C) FHP-L (D) FHP-R. (E) LSP.
Fig 2.
Landmark identification in the 3D model.
(A) Identification of the orbitale point (red). (B) Identification of the left porion point (red). (C) Identification of the left lateral semicircular canal (red) in the axial plane.
Table 1.
Definition of 3D cephalometric landmarks.
Fig 3.
Example of measuring the distances from the reference plane, FHP-P, to the dental landmarks in a 3D CBCT model, and assessing postoperative symmetry according to the distance from the cephalometric points in the midline of the face to the mid-sagittal plane derived from the FHP-P.
Table 2.
Patient information.
Table 3.
Intraobserver reproducibility and interobserver reliability of 3D landmark identification.
Fig 4.
Discrepancies between the right and left distance from landmarks of maxillary and mandibular teeth to 5 reference planes for all participants.
(A) Group 1: before surgery. (B) Group 1: after surgery. (C) Group 2: before surgery. (D) Group 2: after surgery. (E) Group 3: before surgery. (F) Group 3: after surgery.
Table 4.
Mean differences between the right and left distance from landmarks of maxillary and mandibular teeth to the 5 reference planes.
Table 5.
Differences of vertical distance from each point to the reference planes (mm).
Fig 5.
The volumetric difference of specific soft and hard tissue regions after surgery based on the constructed reference planes.
(A) Cranial base superimposition of preoperative and postoperative CBCT models based on the reference planes (e.g., FHP-P). (B) The 3D landmarks were indicated, forming the horizontal and vertical borders of some specific regions based on the constructed reference planes. (C) The volumetric difference of the soft and hard tissue of various regions after subtracting the preoperative and postoperative images.
Table 6.
Comparison of reference planes on assessing facial symmetry.
Table 7.
The soft-to-hard tissue movement ratio in different regions based on the different reference planes.