title: Palatal surface area of maxillary plaster casts--a comparison between two-dimensional and three-dimensional measurements.
abstract: OBJECTIVE
  To investigate the relationship between corresponding two-dimensional and three-dimensional measurements on maxillary plaster casts taken from photographs and three-dimensional surface scans, respectively.
  
  
  METHODS
  Corresponding two-dimensional and three-dimensional measurements of selected linear distances, curve lengths, and (surface) areas were carried out on maxillary plaster casts from individuals with unilateral or bilateral cleft lip and palate. The relationship between two-dimensional and three-dimensional measurements was investigated using linear regression.
  
  
  CONCLUSIONS
  Error sources in the measurement of three-dimensional palatal segment surface area from a two-dimensional photograph were identified as photographic distortion (2.7%), interobserver error (3.3%), variability in the orientation of the plaster cast (3.2%), and natural shape variation (4.6%). The total error of determining the cleft area/palate surface area ratio was 15%. In population studies, the effect of using two-dimensional measurements is a decrease of discriminating power. In well-calibrated setups, a two-dimensional measurement of the cleft area/palate surface area ratio may be converted to a three-dimensional measurement by use of a multiplication factor of 0.75.
authors.affiliation: Department of Pediatric Dentistry and Clinical Genetics, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, and Copenhagen University Hospital, Denmark. tdarvann@lab3d.odont.ku.dk
authors.forename: Tron A
authors.initials: TA
authors.lastname: Darvann
authors.forename: Nuno V
authors.initials: NV
authors.lastname: Hermann
authors.forename: Bjarne K
authors.initials: BK
authors.lastname: Ersbøll
authors.forename: Sven
authors.initials: S
authors.lastname: Kreiborg
authors.forename: Samuel
authors.initials: S
authors.lastname: Berkowitz
mesh_terms: D002508:Cephalometry / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D002972:Cleft Palate / Q000473:pathology*; D004812:Epidemiologic Methods; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007223:Infant; D007231:Infant, Newborn; D003765:Models, Dental; D010159:Palate / Q000473:pathology*; D023861:Photography, Dental / Q000379:methods*