title: Statistical modelling of lip movement in the clinical context.
abstract: OBJECTIVE
  To establish three-dimensional (3D) reference data on average lip movement in normal healthy subjects using statistical shape analysis techniques.
  
  
  METHODS
  School of Dentistry and Cardiff School of Computer Science, Cardiff University, United Kingdom. One hundred and fifteen white subjects.
  
  
  METHODS
  Subjects performed four reproducible verbal gestures (puppy, rope, baby and bob) in a normal relaxed manner, which were captured using a non-invasive, 3D motion scanner (3dMDFace™ Dynamic System). Six landmarks were manually placed around the lips of the 3D facial shells showing maximum lip displacement. Generalized procrustes analysis followed by principal component analysis was applied to the landmark coordinates to characterize lip movement for each word.
  
  
  RESULTS
  The first four principal components (PCs) describe the majority of variation in lip movement for the four words involving a complex interaction of lip movements in three dimensions. Bilateral landmarks were paired within PCs showing that movement was largely symmetrical. Female resting lip shape was narrower and shorter in height than males. During motion, females preferred a more protrusive articulation than males.
  
  
  CONCLUSIONS
  Statistical shape analysis techniques can be used to characterize lip movement during articulation. Data from this study can act as a reference for average lip movement to compare similar population groups.
authors.affiliation: Applied Clinical Research and Public Health, School of Dentistry, Cardiff University, Cardiff, UK. popath@cardiff.ac.uk
authors.forename: H
authors.initials: H
authors.lastname: Popat
authors.forename: A I
authors.initials: AI
authors.lastname: Zhurov
authors.forename: A M
authors.initials: AM
authors.lastname: Toma
authors.forename: S
authors.initials: S
authors.lastname: Richmond
authors.forename: D
authors.initials: D
authors.lastname: Marshall
authors.forename: P L
authors.initials: PL
authors.lastname: Rosin
mesh_terms: D000328:Adult; D059925:Anatomic Landmarks; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D016018:Least-Squares Analysis; D008046:Lip / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D009068:Movement; D019370:Observation; D025341:Principal Component Analysis; D012016:Reference Values; D012737:Sex Factors; D013062:Speech Articulation Tests