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Updated: Mar 7, 2026
A Postoperative Evaluation Guideline for Computer-Assisted Reconstruction of the Mandible
Published on: January 28, 2020
Establishment of a Reliable Horizontal Reference Plane for 3-Dimensional Facial Soft Tissue Evaluation Before and
Peerasak Chortrakarnkij1, Daniel Lonic, Hsiu-Hsia Lin
1From the *Division of Plastic Surgery, Siriraj Hospital, Mahidol University, Bangkok, Thailand; †Plastic and Reconstructive Surgery and Craniofacial Research Center, Chang Gung Memorial Hospital, Chang Gung University; and ‡Craniofacial Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
Background:
This study aims to demonstrate the reliability of our proposed facial reference system in the horizontal axis using 3-dimensional photogrammetry and to find a correlation between this plane and the Frankfurt horizontal (FH) plane.
Methods:
Forty-one patients were enrolled. Three-dimensional facial images were taken before and 6 months after orthognathic surgery. Superimposition was carried out, and differences in landmark position were evaluated. Two constant landmarks were selected to construct a reference system within a standardized reference frame. Cone-beam computed tomography and 3-dimensional facial images were superimposed. Two reference lines were identified, and the angle between these lines was calculated.
Results:
For landmark reliability, 5 landmarks [gnathion, nasion, exocanthion (Ex), endocanthion, and tragion (T)] were constant. Two landmarks (Ex and T) were selected to construct a reference system within a standardized reference frame. For angular measurement, the mean angle between this reference plane and the skeletal FH plane was 17.6 ± 2.0 degrees. There was no statistical difference between sex, side, and preoperative/postoperative timing of photography.
Conclusions:
Our proposed reference plane is constructed from reliable facial Ex and T landmarks. This plane is consistent and crosses the FH plane at 17.6 degrees.
