SLS analysis
SD
The facial scans were processed in Geomagic 2014 (2014, Germany) software by the following steps:
Alignment and registration:The scan of T0 was set to be a fixed module, while the scans of T1 and T2 were floating modules. T1 and T2 scans were registered to T0 according to the upper third of the face [
The registration of T1 with T0 according to the upper third of the face 
Buccal region division.The bilateral buccal regions were divided by the “draw” operation connecting Posterotragion (pt’) to Alare (al’), Exocanthion (ex’) to Cheilion (ch’), Cheilion (ch’) to Chin footpoint (cf’), and multiple points along the lower border of the mandible. The landmark definitions are listed in Table 
The abbreviation and definition of landmarks used in the studyThe upper corner maker (’) refers to Capulometric landmarks (on soft tissue) apart from Craniometric landmarks (on skull)
The mid-sagittal plane establishment.The mid-sagittal plane only established on T0 scan by the orthogonal lasers, Fig. 
The establishment of the mid-sagittal plane according to the orthogonal lasers projected on T0 scan When capture the scan, the horizontal laser will be reflected by the two mirrors behind the subject’s head bilaterally [
Buccal boundary projection.The projection method measures the volume from the buccal area projecting perpendicular to the mid-sagittal plane. To avoid the error of boundary determination between different time point, the buccal boundary was projected from scan T0 to T1 and T2 in the direction perpendicular to the mid-sagittal plane either. Using the right side as an example, the specific process refers to Fig. 
Buccal boundary projection from scan T0 to T1 and T2 in the direction perpendicular to the mid-sagittal plane 
Buccal region deviation analysis.By the “Deviation/ 3D Compare” function, mean (µ), standard deviation (SD), and root mean square (RMS) of the buccal area were calculated. The definition of SD and RMS are as follows. 


Buccal soft tissue volume change (STVC) measurement.Soft tissue volume (STV) is the volume from the buccal region perpendicular to the mid-sagittal plane, Fig. 
The measurement of buccal STV; On the left side from top to bottom are the right buccal models of T0, T1, and T2; Plane 2 is the mid-sagittal plane, and buccal STV is the volume of the buccal patch model projecting to the mid-sagittal plane
The reliability of the projection method.Ten samples were randomly selected by drawing lots for the reliability test. Two well-trained investigators measured the STVC by the projection method independently. One investigator repeated the measurements after a two-week interval.