title: Assessment of the reproducibility of facial expressions with 3-D stereophotogrammetry.
abstract: OBJECTIVE
  There is little research into analyzing whether facial expression changes are secondary to actual treatment or normal day-to-day variation. This study aims to ascertain whether nine-facial expressions were reproducible.
  
  
  METHODS
  Thirty-nine white subjects performed nine-facial expressions, captured by three-dimensional stereophotogrammetry in three sessions. After initial capture (session 1), each expression was repeated after 15 minutes (session 2) and then 4 weeks (session 3) after the initial session. Statistical analysis was performed on the mean variability of facial landmarks between session 1 and 2 and session 1 and 3.
  
  
  RESULTS
  Repose was the most reproducible expression. The least reproducible was "blow-out-the-cheeks." Analysis between session 1 and 2 showed no significant differences in expression reproducibility. Analysis between session 1 and 3 showed significant differences for the "smile-with-lips-open" and "blow-out-the-cheeks" expressions.
  
  
  CONCLUSIONS
  Facial expressions are reproducible in a 15-minute period. There are significant differences in the ability to reproduce facial expressions 4 weeks apart for "smile-with-lips-open" and "blow-out-the-cheeks."
authors.affiliation: Plastic and Reconstructive Surgery Department, Queen Victoria Hospital NHS Foundation Trust, West Sussex, England. drasawyer@hotmail.com
authors.forename: Adam R
authors.initials: AR
authors.lastname: Sawyer
authors.forename: Marlene
authors.initials: M
authors.lastname: See
authors.forename: Charles
authors.initials: C
authors.lastname: Nduka
mesh_terms: D005149:Facial Expression; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010780:Photogrammetry; D015203:Reproducibility of Results