title: Dimensional accuracy of digital dental models from cone-beam computed tomography scans of alginate impressions according to time elapsed after the impressions.
abstract: BACKGROUND
  Our objective was to investigate the dimensional accuracy of digital dental models obtained from the cone-beam computed tomography (CBCT) scans of alginate impressions according to the time elapsed after the impressions were taken.
  
  
  METHODS
  Alginate impressions were obtained of 20 adults using 2 alginate materials: Alginoplast (Heraeus Kulzer, Hanau, Germany) and Cavex (Cavex Holland, Haarlem, The Netherlands). These impressions were stored in wet conditions and scanned by CBCT immediately after impression-taking and after storage times of 12, 24, 36, 48, 60, and 72 hours. After reconstruction of the 3-dimensional digital dental models, the models were measured, and the data were analyzed to determine the dimensional changes according to the time elapsed. The changes within the measurement error were regarded as clinically acceptable in this study.
  
  
  RESULTS
  The measurement errors ranged from 0.27 to 0.29 mm in the digital dental models obtained from CBCT scans of the alginate impressions. All measurements showed decreasing accuracy with greater elapsed time after the impressions were taken. Changes above the measurement error occurred at 24 and 36 hours for Cavex and Alginoplast, respectively.
  
  
  CONCLUSIONS
  Digital dental models can be obtained from CBCT scans of alginate impressions without sending them to a remote laboratory. However, the impressions need to be scanned within 24 hours; otherwise, dimensional changes lead to errors that exceed the error of measurement.
authors.affiliation: Postgraduate student, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Sang-Mi
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Postgraduate student, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Associate professor, Department of Orthodontics, Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea.
authors.forename: Jin-Hyoung
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Professor and chairman, Department of Orthodontics, Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea. Electronic address: hhwang@chonnam.ac.kr.
authors.forename: Hyeon-Shik
authors.initials: HS
authors.lastname: Hwang
mesh_terms: D000328:Adult; D000464:Alginates / Q000737:chemistry*; D000465:Algorithms; D054893:Cone-Beam Computed Tomography / Q000706:statistics & numerical data*; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008422:Materials Testing; D003765:Models, Dental / Q000706:statistics & numerical data*; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000464:Alginates; D003760:Dental Impression Materials; D014867:Water; C050135:cavex