title: The Accuracy and Reproducibility of Linear Measurements Made on CBCT-derived Digital Models.
abstract: OBJECTIVE
  To evaluate the accuracy and reproducibility of linear measurements made on cone-beam computed tomography (CBCT)-derived digital models.
  
  
  METHODS
  A total of 25 patients (44% female, 18.7 ± 4 years) who had CBCT images for diagnostic purposes were included. Plaster models were obtained and digital models were extracted from CBCT scans. Seven linear measurements from predetermined landmarks were measured and analyzed on plaster models and the corresponding digital models. The measurements included arch length and width at different sites. Paired t test and Bland-Altman analysis were used to evaluate the accuracy of measurements on digital models compared to the plaster models. Also, intraclass correlation coefficients (ICCs) were used to evaluate the reproducibility of the measurements in order to assess the intraobserver reliability.
  
  
  RESULTS
  The statistical analysis showed significant differences on 5 out of 14 variables, and the mean differences ranged from -0.48 to 0.51 mm. The Bland-Altman analysis revealed that the mean difference between variables was (0.14 ± 0.56) and (0.05 ± 0.96) mm and limits of agreement between the two methods ranged from -1.2 to 0.96 and from -1.8 to 1.9 mm in the maxilla and the mandible, respectively. The intraobserver reliability values were determined for all 14 variables of two types of models separately. The mean ICC value for the plaster models was 0.984 (0.924-0.999), while it was 0.946 for the CBCT models (range from 0.850 to 0.985).
  
  
  CONCLUSIONS
  Linear measurements obtained from the CBCT-derived models appeared to have a high level of accuracy and reproducibility.
authors.affiliation: Department of Orthodontics, University of Damascus, Dental School, Damascus, Syria.
authors.forename: Ahmad L
authors.initials: AL
authors.lastname: Maroua
authors.affiliation: Department of Orthodontics, University of Damascus, Dental School, Damascus, Syria.
authors.forename: Mowaffak
authors.initials: M
authors.lastname: Ajaj
authors.affiliation: Associate Professor, Department of Orthodontics, University of Damascus, Dental School, Damascus, Syria, Phone: +963940404840 e-mail: myhajeer@gmail.com.
authors.forename: Mohammad Y
authors.initials: MY
authors.lastname: Hajeer
mesh_terms: D000293:Adolescent; D054893:Cone-Beam Computed Tomography; D061827:Dimensional Measurement Accuracy; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D003765:Models, Dental; D015203:Reproducibility of Results
keywords: Accuracy; Cone-beam computed tomography-derived digital models; Plaster models; Reproducibility; Study models.