title: Accuracy and reproducibility of dental replica models reconstructed by different rapid prototyping techniques.
abstract: BACKGROUND
  Rapid prototyping is a fast-developing technique that might play a significant role in the eventual replacement of plaster dental models. The aim of this study was to investigate the accuracy and reproducibility of physical dental models reconstructed from digital data by several rapid prototyping techniques.
  
  
  METHODS
  Twelve mandibular and maxillary conventional plaster models from randomly chosen subjects were selected and served as the gold standard. The plaster models were scanned to form high-resolution 3-dimensional surface models in .stl files. These files were converted into physical models using 3 rapid prototyping techniques: digital light processing, jetted photopolymer, and 3-dimensional printing. Linear measurements on the plaster models were compared with linear measurements on the rapid prototyping models. One observer measured the height and width of the clinical crowns of all teeth (first molar to first molar) on all models (plaster and replicas) using a digital caliper. All models were measured 5 times with a 2-week interval between measurements.
  
  
  RESULTS
  The intraobserver agreement was high (intraclass correlation coefficient >0.94). The mean systematic differences for the measurements of the height of the clinical crowns were -0.02 mm for the jetted photopolymer models, 0.04 mm for the digital light processing models, and 0.25 mm for the 3-dimensional printing models. For the width of the teeth, the mean systematic differences were -0.08 mm for the jetted photopolymer models, -0.05 mm for the digital light processing models, and -0.05 mm for the 3-dimensional printing models.
  
  
  CONCLUSIONS
  Dental models reconstructed by the tested rapid prototyping techniques are considered clinically acceptable in terms of accuracy and reproducibility and might be appropriate for selected applications in orthodontics.
authors.affiliation: Orthodontic resident, Department of Orthodontics, University Medical Center, University of Groningen, Groningen, The Netherlands.
authors.forename: Aletta
authors.initials: A
authors.lastname: Hazeveld
authors.affiliation: Assistant professor, Department of Oral and Maxillofacial Surgery, University Medical Center, University of Groningen, Groningen, The Netherlands.
authors.forename: James J R
authors.initials: JJ
authors.lastname: Huddleston Slater
authors.affiliation: Professor, Department of Orthodontics, University Medical Center, University of Groningen, Groningen, The Netherlands. Electronic address: y.ren@umcg.nl.
authors.forename: Yijin
authors.initials: Y
authors.lastname: Ren
mesh_terms: D001641:Bicuspid / Q000033:anatomy & histology; D002133:Calcium Sulfate / Q000737:chemistry; D002508:Cephalometry / Q000706:statistics & numerical data; D017076:Computer-Aided Design / Q000706:statistics & numerical data*; D003481:Cuspid / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000033:anatomy & histology; D008334:Mandible / Q000033:anatomy & histology; D008437:Maxilla / Q000033:anatomy & histology; D003765:Models, Dental / Q000706:statistics & numerical data*; D008963:Molar / Q000033:anatomy & histology; D009811:Odontometry / Q000706:statistics & numerical data; D011108:Polymers / Q000737:chemistry; D011327:Printing / Q000379:methods; D015203:Reproducibility of Results; D012984:Software; D013499:Surface Properties; D013674:Technology, Dental / Q000706:statistics & numerical data; D019228:Tooth Crown / Q000033:anatomy & histology
chemical_list: D011108:Polymers; D002133:Calcium Sulfate