title: A Quantitative Analysis of Lip Aesthetics: The Influence of Gender and Aging.
abstract: BACKGROUND
  The quantitative analysis of sexual dimorphism of facial structures may valuably support reconstructive and feminization surgery, thanks to the estimation of metrical thresholds useful for distinguishing male and female traits. This study aims at verifying the metrical characteristics of female and male lips, to provide indications for aesthetic surgery.
  
  
  METHODS
  Thirty healthy Caucasian volunteers (20 men and 20 women) were divided into two groups according to age: 21-34 years and 45-65 years. Arches and the cutaneous (external) and mucosal (internal) labial surfaces were reproduced by stone models, and digitised using a computerised electromechanical instrument. Area, volume and thickness were measured separately for the upper and lower lips, and compared between sexes and ages by Student's t test, and multinomial logistic regression.
  
  
  RESULTS
  All lip measurements were larger in males than in females; upper lip thickness best divided males from females, adopting a 9.5-mm threshold (percentage of correct diagnosis: 85 %). Young subjects always showed higher measurements than old subjects; lower lip thickness provided the highest percentage of correct age diagnosis (85 %, adopting a 13.8-mm threshold).
  
  
  CONCLUSIONS
  This study provides novel thresholds that may contribute to the assessment of adequate reconstruction of lips in aesthetic surgery.
  
  
  METHODS
  This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .
authors.affiliation: Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano, Via Mangiagalli 31, 20133, Milan, Italy, daniele.gibelli@unimi.it.
authors.forename: Daniele
authors.initials: D
authors.lastname: Gibelli
authors.forename: Marina
authors.initials: M
authors.lastname: Codari
authors.forename: Riccardo
authors.initials: R
authors.lastname: Rosati
authors.forename: Claudia
authors.initials: C
authors.lastname: Dolci
authors.forename: Gianluca Martino
authors.initials: GM
authors.lastname: Tartaglia
authors.forename: Cristina
authors.initials: C
authors.lastname: Cattaneo
authors.forename: Chiarella
authors.initials: C
authors.lastname: Sforza
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D004954:Esthetics; D005069:Evaluation Studies as Topic; D019317:Evidence-Based Medicine; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008046:Lip / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012737:Sex Factors; D044465:White People; D055815:Young Adult