title: Mentolabial angle and aesthetics: a quantitative investigation of idealized and normative values.
abstract: BACKGROUND
  This study is a quantitative evaluation of the influence of the mentolabial angle on perceived attractiveness and threshold values of desire for surgery.
  
  
  METHODS
  The mentolabial angle of an idealized silhouette male Caucasian profile image was altered incrementally between 84° and 162°. Images were rated on a Likert scale by pretreatment orthognathic patients (n= 75), lay people (n= 75) and clinicians (n= 35).
  
  
  RESULTS
  A mentolabial angle of approximately 107° to 118° was deemed the most attractive, with a range of up to 140° deemed acceptable. Angles above or below this range were perceived as unattractive, and anything outside the range of below 98° or above 162° was deemed very unattractive. A deep mentolabial angle (84°) or an almost flat angle (162°) was deemed the least attractive. In terms of threshold values of desire for surgery, for all groups, a threshold value of ≥162° and ≤84° indicated a preference for surgery, although clinicians were least likely to suggest surgery. The clinician group was the most consistent, and for many of the images, there was some variation in agreement between clinicians and lay people as to whether surgery is required. There was even more variability in the assessments for the patient group.
  
  
  CONCLUSIONS
  It is recommended that in orthognathic and genioplasty planning, the range of normal variability of the mentolabial angle, in terms of observer acceptance, is taken into account as well as threshold values of desire for surgery. The importance of using patients as observers in attractiveness research is stressed.
authors.affiliation: Consultant Orthodontist/Honorary Senior Lecturer, Kingston and St George's Hospitals and St George's Medical School, London, UK.
authors.forename: Farhad B
authors.initials: FB
authors.lastname: Naini
authors.affiliation: Professor and Head of Orthodontics and Craniofacial Development, King's College London Dental Institute, London, UK.
authors.forename: Martyn T
authors.initials: MT
authors.lastname: Cobourne
authors.affiliation: Professor of Orthodontics, Department of Reconstructive and Diagnostic Surgical Sciences, University of Milan, Milan, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Garagiola
authors.affiliation: Professor of Orthodontics, King's College London Dental Institute, London, UK.
authors.forename: Fraser
authors.initials: F
authors.lastname: McDonald
authors.affiliation: Professor, Faculty of Science, Engineering and Computing, Kingston University, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Wertheim
keywords: Attractiveness; Facial; Labiomental angle; Labiomental fold; Mentolabial angle; Profile aesthetics