# Three-Dimensional Change of Lip after Two-Jaw Surgery in Facial Asymmetry Using Facial Scanner
## 2 Materials and Methods
### Superimposition Process  
To use the same 3D coordinate system for the CT image, the preoperative (T1) FS image was registered on the CT image using Geomagic Design X software (3D Systems, Morrisville, NC, USA). For an initial register, seven landmarks (right and left exconathions (Ex), right and left endocathions (En), right and left nasal alas (Al), and soft tissue nasion (N')) were used as reference points to superimpose the T1 CT and T1 FS images. Subsequently, the iterative closest point algorithm was used for fine registration with the seven reference points, the wide surface of the forehead, and the dorsum of the nose. Finally, the superimposed 3D images with the same coordinate system were imported into the Morpheus system (Figure 1) [20]. For hard tissue superimposition, the T1 and T2 Digital imaging and Communications in Medicine (DICOM) images of each patient were imported, and voxel-based registration was performed on the anterior cranial base to exclude the volume of the jaw affected by orthognathic surgery using Ondemand3D software (CyberMed Inc., Seoul, Korea). For soft tissue superimposition, the T1 and T2 FS images of each patient were imported, and the registration was carried out using Morpheus 3D (Morpheus, Seoul, Korea) software with five reference points (right and left Ex, right and left En, and N') and the wide surface of the forehead and nasal bridge (Figure 2). Figure 1: Registration of preoperative (T1) CT and FS images. The references used for superimposition were the forehead and the dorsum of the nose area (blue color), exocanthions, endocanthions, and nasal alas: N’, soft tissue nasion; Ex, exocanthion; En, endocanthion; Al, nasal ala; CT, computed tomography; and FS, facial scanner. A total of 11 landmarks were identified (Figure 3, Table 2) and measured in the 3D coordinate system before (T1) and after (T2) surgery using Ondemand3D and Morpheus 3D software. The changes in all landmarks were evaluated in the transverse (x), anteroposterior (y), and vertical axes (z). Figure 3: Hard tissue and soft tissue landmarks used in this study. MSP, midsagittal plane; U3-D/ND, maxillary canine cusp tip on the deviated side/non-deviated side; U6-D/ND, maxillary 1 st molar mesiobuccal cusp tip on the deviated side/non-deviated side; Mf-D/ND, mental foramen on the deviated side/non-deviated side; Me, menton; Ls, labrale superius; Li, labrale inferius; and Ch-D/ND, chelinion on the deviated side/non-deviated side. Figure 2: Superimposition of preoperative (T1) and postoperative (T2) images of the facial scanner. The references used for superimposition were the forehead and nasal bridge area (blue color), exocanthions, endocanthions, and nasal alas. (**A**) Preoperative FS image, (**B**) postoperative FS image, and (**C,D**) superimposed images. N’, soft tissue nasion; Ex, exocanthion; En, endocanthion; and Al, nasal ala. The lip planes were constructed to simplify and effectively evaluate their three-dimensional changes. The upper lip planes were established by connecting both sides of the cheliion (Ch) and labrale superius (Ls). The lower lip planes were also established by connecting both sides of the Ch and labrale inferius (Li). Three-dimensional changes in the lip planes before and after surgery were evaluated in the coronal, sagittal, and axial planes (Figure 4).