title: Validity, reliability, and reproducibility of linear measurements on digital models obtained from intraoral and cone-beam computed tomography scans of alginate impressions.
abstract: BACKGROUND
  Digital 3-dimensional models are widely used for orthodontic diagnosis. The aim of this study was to assess the validity, reliability, and reproducibility of digital models obtained from the Lava Chairside Oral scanner (3M ESPE, Seefeld, Germany) and cone-beam computed tomography scans of alginate impressions for tooth-width measurements and the Bolton analysis.
  
  
  METHODS
  A digital model, an intraoral scan, and a plaster model were made for each of 22 subjects. Tooth-width measurements on the digital model and the intraoral scan were compared with those on the corresponding plaster models (gold standard). Intraclass correlation coefficients were calculated to determine the interexaminer reliability of the measurements of each method. The anterior and overall Bolton ratios were calculated for each participant and for each method. The paired t test was used to determine the validity. The scanning time for the intraoral scanner was registered and analyzed.
  
  
  RESULTS
  Tooth-width measurements of each tooth on the digital models and the intraoral scans did not differ significantly from those on the plaster models (P >0.05). The overall and anterior Bolton ratios from the 2 types of digital models differed significantly from the gold standard (P <0.05). However, the differences never exceeded 1.5 mm; this could be regarded as clinically insignificant. The scanning times of the intraoral scanner decreased significantly with the number of scans performed.
  
  
  CONCLUSIONS
  Both intraoral scanning and cone-beam computed tomography scanning of alginate impressions are valid, reliable, and reproducible methods to obtain dental measurements for diagnostic purposes.
authors.affiliation: Resident, Department of Orthodontics, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands. m.g.wiranto@umcg.nl
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Wiranto
authors.forename: W Petrie
authors.initials: WP
authors.lastname: Engelbrecht
authors.forename: Heleen E
authors.initials: HE
authors.lastname: Tutein Nolthenius
authors.forename: W Joerd
authors.initials: WJ
authors.lastname: van der Meer
authors.forename: Yijin
authors.initials: Y
authors.lastname: Ren
mesh_terms: D000464:Alginates; D054893:Cone-Beam Computed Tomography; D003761:Dental Impression Technique; D005145:Face / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D003765:Models, Dental; D009811:Odontometry / Q000379:methods*; D019252:Radiography, Dental, Digital / Q000379:methods; D015203:Reproducibility of Results
chemical_list: D000464:Alginates