title: Fit of 4-unit FDPs from CoCr and zirconia after conventional and digital impressions.
abstract: OBJECTIVE
  To evaluate the marginal and internal fit of CAD/CAM-generated frameworks for 4-unit, fixed dental prostheses (FDPs) from zirconia (Z) and cobalt-chromium alloy (C) made with conventional (CI) and digital impressions (DI).
  
  
  METHODS
  A titanium model was digitized with an intraoral scanner (DI, LAVA™ C.O.S.; 3M ESPE; Seefeld, Germany; n = 12). Additionally, 12 conventional impressions were taken, and referring plaster casts were digitized by a laboratory-scanner (CI, LAVA™ Scan ST; 3M ESPE; n = 12). Frameworks were fabricated (3M ESPE) from cobalt-chromium (DI-C, n = 12; CI-C, n = 12) and zirconia (DI-Z, n = 12; CI-Z, n = 12) from the same datasets. A replica technique was applied to measure the accuracy. The Mann-Whitney U statistical test was applied to detect statistical differences between each material and methodology groups in terms of fit.
  
  
  RESULTS
  Frameworks from DI-C (median 19.07 μm) showed significantly better marginal fit than CI-C (median 64.64 μm, p < 0.001). Frameworks from DI-Z (median 52.50 μm) showed significantly better marginal fit than CI-Z (median 72.94 μm, p = 0.001). Additionally, frameworks from DI-C showed a significantly better marginal fit than DI-Z (p < 0.001).
  
  
  CONCLUSIONS
  CI and DI led to a clinically acceptable marginal fit of 4-unit FDPs from cobalt-chromium and zirconia. DI leads to better marginal fit of the cobalt-chromium frameworks; however, no effect on zirconia was found.
  
  
  CONCLUSIONS
  The results indicate that DI is suitable for fabricating 4-unit, cobalt-chromium and zirconia frameworks with regard to fit requirements.
authors.affiliation: Comprehensive Dental Care, Oral Implant Center, Niigata Hospital, The Nippon Dental University, 1-8, Hamaura-cho, Chuo-ku, Niigata, 951-8580, Japan.|Department of Prosthodontics, Dental School of the Ludwig-Maximilian University of Munich, Goethestrasse 70, 80336, München, Germany.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Department of Prosthodontics, Charité UniversityMedicine Berlin, Assmanshauser Str. 4-6, 14197, Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Beuer
authors.affiliation: Department of Prosthodontics, Dental School of the Ludwig-Maximilian University of Munich, Goethestrasse 70, 80336, München, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Stimmelmayr
authors.affiliation: Department of Prosthodontics, Dental School of the Ludwig-Maximilian University of Munich, Goethestrasse 70, 80336, München, Germany.
authors.forename: Kurt
authors.initials: K
authors.lastname: Erdelt
authors.affiliation: Department of Prosthodontics, Dental School of the Ludwig-Maximilian University of Munich, Goethestrasse 70, 80336, München, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Keul
authors.affiliation: Department of Prosthodontics, Dental School of the Ludwig-Maximilian University of Munich, Goethestrasse 70, 80336, München, Germany. Jan_frederik.gueth@med.uni-muenchen.de.
authors.forename: Jan-Frederik
authors.initials: JF
authors.lastname: Güth
mesh_terms: D002858:Chromium Alloys; D017076:Computer-Aided Design; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D003779:Denture Design; D003830:Denture, Partial, Fixed; D055119:Elastic Modulus; D014025:Titanium; D015040:Zirconium
chemical_list: D002858:Chromium Alloys; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
keywords: CAD/CAM; Cobalt-chromium alloy; Digital impression; Fixed dental prostheses; Intraoral scanner; Marginal fit; Zirconia