title: Precision of landmark positioning on digitized models from patients with cleft lip and palate.
abstract: OBJECTIVE
  To quantify the precision of landmark positioning on digitized casts of patients with unilateral cleft lip and palate.
  
  
  METHODS
  Forty plaster models of newborns up to 8 months of age were selected from the archive of the Department of Orthodontics of the University of Heidelberg.
  
  
  METHODS
  The plaster-cast models were digitized with a Micromeasure 70 three-dimensional laser scanner (Micromeasure, Bischoffen, Germany). The laser scanner used in this study operates with a precision of 0.15 mm on the x- and y-axes and 0.06 mm on the z-axis. In the intraobserver study, a single observer placed anatomical landmarks in four rounds, with at least 4 weeks between each round. In the interobserver study, four different observers each placed the same landmarks once. For the two different studies, an ideal location for each landmark was calculated by averaging the landmark positions of the four rounds or observers. The distance between each of the four landmark positions and the ideal landmark was measured.
  
  
  RESULTS
  A 95% confidence interval for the landmark positioning error was calculated. For the intraobserver investigation, this error was 0.34 to 1.30 mm, and for the interobserver investigation it was 0.7 to 2.00 mm.
  
  
  CONCLUSIONS
  Because both investigations displayed comparable error intervals, it was concluded that different observers could perform landmark positioning for the same studies.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University of Heidelberg, Heidelberg, Germany.
authors.forename: Jakob
authors.initials: J
authors.lastname: Brief
authors.forename: Jan H
authors.initials: JH
authors.lastname: Behle
authors.forename: Angelika
authors.initials: A
authors.lastname: Stellzig-Eisenhauer
authors.forename: Stefan
authors.initials: S
authors.lastname: Hassfeld
mesh_terms: D002971:Cleft Lip / Q000473:pathology; D002972:Cleft Palate / Q000473:pathology; D016001:Confidence Intervals; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D007223:Infant; D007231:Infant, Newborn; D007834:Lasers; D008953:Models, Anatomic; D003765:Models, Dental; D015588:Observer Variation; D012015:Reference Standards