title: Measurements using orthodontic analysis software on digital models obtained by 3D scans of plaster casts : Intrarater reliability and validity.
abstract: OBJECTIVE
  The purpose of this work was to determine the reliability and validity of measurements performed on digital models with a desktop scanner and analysis software in comparison with measurements performed manually on conventional plaster casts.
  
  
  METHODS
  A total of 20 pairs of plaster casts reflecting the intraoral conditions of 20 fully dentate individuals were digitized using a three-dimensional scanner (D700; 3Shape). A series of defined parameters were measured both on the resultant digital models with analysis software (Ortho Analyzer; 3Shape) and on the original plaster casts with a digital caliper (Digimatic CD-15DCX; Mitutoyo). Both measurement series were repeated twice and analyzed for intrarater reliability based on intraclass correlation coefficients (ICCs). The results from the digital models were evaluated for their validity against the casts by calculating mean-value differences and associated 95 % limits of agreement (Bland-Altman method). Statistically significant differences were identified via a paired t test.
  
  
  RESULTS
  Significant differences were obtained for 16 of 24 tooth-width measurements, for 2 of 5 sites of contact-point displacement in the mandibular anterior segment, for overbite, for maxillary intermolar distance, for Little's irregularity index, and for the summation indices of maxillary and mandibular incisor width. Overall, however, both the mean differences between the results obtained on the digital models versus on the plaster casts and the dispersion ranges associated with these differences suggest that the deviations incurred by the digital measuring technique are not clinically significant.
  
  
  CONCLUSIONS
  Digital models are adequately reproducible and valid to be employed for routine measurements in orthodontic practice.
authors.affiliation: Department of Orthodontics, Martin Luther University, Große Steinstrasse 19, 06108, Halle (Saale), Germany. judith.czarnota@medizin.uni-halle.de.
authors.forename: Judith
authors.initials: J
authors.lastname: Czarnota
authors.affiliation: Department of Prosthodontics, Martin Luther University, Große Steinstrasse 19, 06108, Halle (Saale), Germany.
authors.forename: Jeremias
authors.initials: J
authors.lastname: Hey
authors.affiliation: Department of Orthodontics, Martin Luther University, Große Steinstrasse 19, 06108, Halle (Saale), Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Fuhrmann
mesh_terms: D002370:Casts, Surgical; D003198:Computer Simulation; D003735:Dental Casting Technique; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007568:Jaw / Q000033:anatomy & histology*; D008954:Models, Biological; D009811:Odontometry / Q000379:methods*; D009970:Orthodontics / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software
keywords: Dental models; Digital models; Orthodontics; Plaster casts; Three-dimensional imaging