Table 6. Comparison of reference planes on assessing facial symmetry.
| Distance of point to mid-sagittal plane (mm) | FHP-P | FHP-O | FHP-L | FHP-R | ||
|---|---|---|---|---|---|---|
| Pre-operation | ANS | +1.75 | +1.12 | +1.71 | +1.80 | |
| UI | +2.95 | +1.99 | +2.88 | +3.17 | ||
| LI | +7.66 | +6.71 | +7.59 | +7.73 | ||
| Pog | +9.87 | +8.68 | +9.79 | +9.95 | ||
| Me | +11.82 | +10.31 | +11.46 | +11.63 | ||
| p-value | 0.9 | |||||
| Post-operation | ANS | +0.64 | +0.34 | +0.62 | +0.67 | |
| UI | +1.38 | +0.92 | +1.35 | +1.41 | ||
| LI | +1.54 | +1.10 | +1.51 | +1.57 | ||
| Pog | +3.14 | +2.54 | +3.11 | +3.19 | ||
| Me | +3.32 | +2.71 | +3.28 | +3.37 | ||
| p-value | 0.6 | |||||
The mid-sagittal plane was defined as the plane passing the nasion and basion and perpendicular to each FHP. Table 1 lists the definition of landmarks ANS, UI, LI, Pog, and Me. The positive sign indicates that the landmarks were located on the right side of the mid-sagittal plane. The p value was calculated from the distance groups to represent the difference among various planes.