title: Accuracy of stereolithographically printed digital models compared to plaster models.
abstract: OBJECTIVE
  This study compared the accuracy of plaster models from alginate impressions and printed models from intraoral scanning.
  
  
  METHODS
  A total of 28 volunteers were selected and alginate impressions and intraoral scans were used to make plaster models and digital models of their dentition, respectively. The digital models were printed using a stereolithographic (SLA) 3D printer with a horseshoe-shaped design. Two calibrated examiners measured distances on the plaster and printed models with a digital caliper. The paired t test was used to determine intraobserver error and compare the measurements. The Pearson correlation coefficient was used to evaluate the reliability of measurements for each model type.
  
  
  RESULTS
  The measurements on plaster models and printed models show some significant differences in tooth dimensions and interarch parameters, but these differences were not clinically relevant, except for the transversal measurements. The upper and lower intermolar distances on the printed models were statistically significant and clinically relevant smaller.
  
  
  CONCLUSIONS
  Printed digital models with the SLA 3D printer studied, with a horseshoe-shaped base made from intraoral scans cannot replace conventional plaster models from alginate impressions in orthodontics for diagnosis and treatment planning because of their clinically relevant transversal contraction.
authors.affiliation: Department of Orthodontics, Dental School, Federal Fluminense University, Mário Santos Braga Street 30, 2nd Floor, Room 214, Niteroi, RJ, 24020-140, Brazil. leocamardella@globo.com.
authors.forename: Leonardo Tavares
authors.initials: LT
authors.lastname: Camardella
authors.affiliation: Department of Orthodontics, Dental School, Federal Fluminense University, Mário Santos Braga Street 30, 2nd Floor, Room 214, Niteroi, RJ, 24020-140, Brazil.
authors.forename: Oswaldo V
authors.initials: OV
authors.lastname: Vilella
authors.affiliation: Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Marleen M
authors.initials: MM
authors.lastname: van Hezel
authors.affiliation: Department of Orthodontics and Craniofacial Biology, Radboud University Medical Centre, Nijmegen, The Netherlands.
authors.forename: Karel H
authors.initials: KH
authors.lastname: Breuning
mesh_terms: D000328:Adult; D002133:Calcium Sulfate; D003198:Computer Simulation; D000078331:Correlation of Data; D006801:Humans; D003765:Models, Dental; D009970:Orthodontics; D023861:Photography, Dental; D066330:Printing, Three-Dimensional; D000076227:Stereolithography
chemical_list: D002133:Calcium Sulfate
keywords: Accuracy; Digital dental models; Intraoral scanning; Printed models