title: Three-dimensional evaluation of the reproducibility of presintered zirconia single copings fabricated with the subtractive method.
abstract: BACKGROUND
  Reproducibility is an important factor determining the success of a prosthesis. However, no studies have focused on identifying the location of errors on prostheses fabricated with the subtractive method, leading to a lack of standards for reproducibility evaluations.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the reproducibility of the subtractive method by conducting 3-dimensional assessments of presintered single-tooth zirconia copings for different teeth.
  
  
  METHODS
  Acrylic resin tooth molds for the canine (CAN), premolar (PRE), and molar (MOL) were used to prepare stone casts, and copings were designed and fabricated with the subtractive method. The intaglio surfaces of corresponding presintered zirconia copings were scanned with a blue light scanner. Initial scan data were used as a reference for comparisons with subsequent data for the measurement of errors. Nine color-difference maps were created for each of the 3 groups and used to calculate root-mean-square (RMS) error values. One-way analysis of variance and the Tukey honestly significant difference tests were used for statistical evaluations (α=.05).
  
  
  RESULTS
  MOL copings exhibited the highest RMS error value (9.22 ±1.56 μm), which was significantly different from values for CAN (3.33 ±2.65 μm) and PRE (4.00 ±2.40 μm; P<.001) copings. Color-difference maps revealed maximum errors in the line angles.
  
  
  CONCLUSIONS
  The highest reproducibility was observed for the CAN copings. The clinical reproducibility of the subtractive method can be improved by avoiding sharp angles during abutment preparation and careful reproduction of angles during prosthesis fabrication.
authors.affiliation: Doctoral student, Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, South Korea.
authors.forename: Chong-Myeong
authors.initials: CM
authors.lastname: Kim
authors.affiliation: Assistant professor, Department of Dental Technology, Medical Campus, KyungDong University, Gangwon-do, South Korea.
authors.forename: Jin-Hun
authors.initials: JH
authors.lastname: Jeon
authors.affiliation: Professor, Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, South Korea.
authors.forename: Ji-Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Associate Professor, Department of Dental Laboratory Science and Engineering, College of Health Science, and Department Public Health Sciences, Korea University, Seoul, South Korea.
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Kim
authors.affiliation: Professor, Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, South Korea. Electronic address: kuc2842@korea.ac.kr.
authors.forename: Woong-Chul
authors.initials: WC
authors.lastname: Kim
mesh_terms: D000180:Acrylic Resins; D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D017267:Dental Prosthesis Design; D006801:Humans; D021621:Imaging, Three-Dimensional; D015203:Reproducibility of Results; D015040:Zirconium
chemical_list: D000180:Acrylic Resins; D015040:Zirconium; C028541:zirconium oxide