Purpose: Organs and structures develop symmetrically, but various degrees of asymmetry can also develop because of the effects of function and disease. The human face is often asymmetrical, but faces can be perceived as beautiful even if they are asymmetrical. The purpose of the present study was to investigate horizontal angular asymmetry of the face.
Materials and methods: The angle between the horizontal line through the bilateral exocanthions and the line though the bilateral mouth corners of the face was measured on standardized frontal facial photographs of 1,282 volunteers (18 to 29 years of age; 761 males, 521 females).
Results: The magnitude of the angle was 0.2 +/- 1.4 and 0.3 +/- 1.3 degrees (mean +/- SD) in males and females, respectively. Faces were classified into 3 types relative to the parallel type. The incidence of the parallel type, the right-dominant type (>/=1 degree), and the left-dominant type (</=1 degree) was 54.7%, 28.6%, and 16.7%, respectively. The right-dominant type was observed more frequently than the left-dominant type in both genders.
Conclusion: Our findings concur with those of previous studies of facial asymmetry and suggest that measurement of horizontal angulations of frontal photographs of faces can be used to assess facial asymmetry.