title: Digital and plaster models: a comparison of measurements and times.
abstract: BACKGROUND
  The objective of this study was to compare the accuracy of measurements carried out using software on digital models with measurements made by hand on conventional plaster models, and to evaluate the time required for each method.
  
  
  METHODS
  Twenty orthodontists were given copies of the same plaster model and asked to carry out measurements of the intercanine distance, anterior width, posterior width, anterior sector, middle sector and posterior sector using a traditional Boley gauge. The same measurements were then carried out on the 3D models by the same specialists using software developed by Padova's Faculty of Engineering of Information, and Student's t test was subsequently employed to compare the reliability and validity of the measurements obtained.
  
  
  RESULTS
  Student's t test for paired data detected no difference between the measurements carried out using the software method and those obtained by the gauge in any of the six parameters, but the former method was found to be conspicuously more rapid than the latter.
  
  
  CONCLUSIONS
  Measurements carried out on 3D models are a valid and reliable alternative to those currently used on plaster models in orthodontic practice, with the advantage of significantly reducing measurement times.
authors.affiliation: Department of Orthodontics, University of Ferrara, Italy. antoniogracco@libero.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Gracco
authors.forename: Mauro
authors.initials: M
authors.lastname: Buranello
authors.forename: Mauro
authors.initials: M
authors.lastname: Cozzani
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Siciliani
mesh_terms: D003198:Computer Simulation; D006801:Humans; D021621:Imaging, Three-Dimensional; D003765:Models, Dental; D015203:Reproducibility of Results; D012984:Software; D018709:Statistics, Nonparametric; D013997:Time Factors