Relative facial size: As shown in Figure 1, the ratio of the distance between the external canthus and the corner of the lips of both face sides, named reference lines, was defined as relative facial size. If the distance between the external canthus and the corner of the lips of both face sides was the same, the face was symmetric based on this parameter.[7 (link),8 (link)][12 (link)] However, when these lines were different, for better comparison of patients, the amount of the longer reference line was divided into the other line and the result was named relative facial size parameter.
Facial angle: As shown in Figure 1, this parameter was measured by calculating the angle between the two following lines; the first line connected two external canthi (line A in Figure 1) and the second line connected the two lips corners (line B in Figure 1). If two lines were parallel, the face was symmetric based on this parameter, however, the presence of an angular difference means facial asymmetry.[7 (link),8 (link)][12 (link)]All quantitative parameters were calculated three times, and the average was reported as a result.