title: The effect of sex and age on facial asymmetry in healthy subjects: a cross-sectional study from adolescence to mid-adulthood.
abstract: OBJECTIVE
  The study assessed the effects of sex and age on 3-dimensional (3D) soft-tissue facial asymmetry.
  
  
  METHODS
  The 3D coordinates of selected soft-tissue facial landmarks were digitized on 314 healthy white subjects (40 male and 33 female adolescents, aged 12 to 15 years; 73 female and 89 male young adults, aged 18 to 30 years; and 41 male and 38 female adults, aged 31 to 56 years) by an electromagnetic instrument. Facial asymmetry was quantified by detecting a plane of symmetry and the centers of gravity of the right and left hemifaces and by calculating the distance between the 2 centers of gravity (distance from the symmetry [DFS]). Both absolute (millimeters) and percentage (of the nasion-center of gravity distance) DFS were obtained, as well as the maximum normal asymmetry. The asymmetry of single landmarks was also quantified.
  
  
  RESULTS
  No gender- or age-related differences were found for both absolute and percentage DFS (P > .05). The maximum normal asymmetry was slightly greater in females than in males of corresponding age; within each sex, the largest values were found in the adolescent group. Tragion, gonion, and zygion were the most asymmetric landmarks in all groups (about 10% to 12% of the nasion-facial center of gravity distance), whereas the least asymmetric was endocanthion (4% to 6%).
  
  
  CONCLUSIONS
  A slight soft-tissue facial asymmetry was found in normal subjects. The maximum normal asymmetry could be useful in identifying borderline asymmetric patients.
authors: Functional Anatomy Research Center, Dipartimento di Anatomia Umana, Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Italy. farc@unimi.it
authors: V F
authors: VF
authors: Ferrario
authors: C
authors: C
authors: Sforza
authors: V
authors: V
authors: Ciusa
authors: C
authors: C
authors: Dellavia
authors: G M
authors: GM
authors: Tartaglia
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002680:Chin / Q000473:pathology; D003430:Cross-Sectional Studies; D004431:Ear, External / Q000473:pathology; D055590:Electromagnetic Phenomena; D005123:Eye / Q000473:pathology; D005145:Face; D005146:Facial Asymmetry / Q000145:classification* / Q000473:pathology; D005260:Female; D005624:Frontal Bone / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008046:Lip / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009666:Nose / Q000473:pathology; D009915:Orbit / Q000473:pathology; D012737:Sex Factors; D013701:Temporal Bone / Q000473:pathology; D015050:Zygoma / Q000473:pathology