title: Comparison of an analog and digital quantitative and qualitative analysis for the fit of dental copings.
abstract: BACKGROUND
  Precision in fit is crucial for dental crowns and bridges. Most analyses of fit are based on analog 2D techniques. Aim of this in-vitro study was to compare an analog and a digital quantitative and qualitative analysis for the fit of CAD/CAM fabricated dental copings.
  
  
  METHODS
  A prepared steel canine served as master die. CAD surface models, varying in data density, were purposely enlarged in height (Ez), circumference (Exy) and both of these aspects at once (Exyz). Two titanium copings for each variation were produced. The silicone-replica-technique was applied to analyze the fit by means of a 2D analog light microscope measurement (LMM) and a 3D computer-assisted measurement using an optical digitizing system (ODKM97), respectively.
  
  
  RESULTS
  In most cases, restorations based on the low data density showed a better fit than those based on high data density. Original size low density data showed the lowest marginal and axial values in the quantitative 2D analyses (LMM and ODKM97). The 3D measurements (ODKM97) revealed best fit of the low density original size specimens, whereas the Ez specimens showed the highest values. Noticeable variations in fit were detected marginally and axially depending on the specific measurement point (mesial, distal, oral, or buccal) for both measurement systems.
  
  
  CONCLUSIONS
  The analog 2D replica technique revealed a loss of information due to the necessary cutting process. By contrast, the digital computer-based method provided 3D quantitative and qualitative results without data loss over the complete surface.
authors.affiliation: Center of Dentistry, Department of Prosthetic Dentistry, Ulm University, 89081 Ulm, Germany. Electronic address: katharina.kuhn@uniklinik-ulm.de.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kuhn
authors.affiliation: Department of Prosthetic Dentistry, Dresden University of Technology, University Hospital Carl Gustav Carus, Dental School, Fetscherstrasse 74, 01309 Dresden, Germany. Electronic address: ostertagbenzinger@yahoo.de.
authors.forename: Silke
authors.initials: S
authors.lastname: Ostertag
authors.affiliation: Department of Prosthetic Dentistry, Dresden University of Technology, University Hospital Carl Gustav Carus, Dental School, Fetscherstrasse 74, 01309 Dresden, Germany. Electronic address: computerzaehne@computerzaehne.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Ostertag
authors.affiliation: Department of Prosthetic Dentistry, Dresden University of Technology, University Hospital Carl Gustav Carus, Dental School, Fetscherstrasse 74, 01309 Dresden, Germany. Electronic address: michael.walter@uniklinikum-dresden.de.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Walter
authors.affiliation: Center of Dentistry, Department of Prosthetic Dentistry, Ulm University, 89081 Ulm, Germany; Department of Prosthetic Dentistry, Dresden University of Technology, University Hospital Carl Gustav Carus, Dental School, Fetscherstrasse 74, 01309 Dresden, Germany. Electronic address: ralph.luthardt@computerzaehne.de.
authors.forename: Ralph G
authors.initials: RG
authors.lastname: Luthardt
authors.affiliation: Center of Dentistry, Department of Prosthetic Dentistry, Ulm University, 89081 Ulm, Germany; Department of Prosthetic Dentistry, Dresden University of Technology, University Hospital Carl Gustav Carus, Dental School, Fetscherstrasse 74, 01309 Dresden, Germany. Electronic address: heike.rudolph@computerzaehne.de.
authors.forename: Heike
authors.initials: H
authors.lastname: Rudolph
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns; D003481:Cuspid / Q000033:anatomy & histology; D017267:Dental Prosthesis Design / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D003765:Models, Dental
keywords: CAD; CAM; Computer-assisted; Data density; Dental restoration fit; Digitizing; Point cloud; Replica-technique; Three-dimensional analysis