title: Randomized controlled clinical trial of zirconia-ceramic and metal-ceramic posterior fixed dental prostheses: a 3-year follow-up.
abstract: OBJECTIVE
  The aim of this study was to test whether posterior fixed dental prostheses (FDPs) with zirconia frameworks exhibit similar survival rates and technical and biologic outcomes as those with metal frameworks.
  
  
  METHODS
  Fifty-nine patients in need of 76 FDPs replacing one to three posterior teeth (molars and premolars) were included in the study. The three- to five-unit FDPs were randomly assigned to 38 zirconia-ceramic and 38 metal-ceramic FDPs. At baseline, 6 months, and 1 to 3 years after cementation, the technical outcome of the reconstructions was examined using the United States Public Health Service (USPHS) criteria. The biologic outcome was analyzed at test (abutment) and control (contralateral) teeth by assessing: probing pocket depth (PPD), probing attachment level (PAL), plaque control record (PCR), bleeding on probing (BOP), and tooth vitality. Radiographs of the FDPs were made. Statistical analysis was performed by applying Kaplan-Meier, Pearson chi-square, Fisher exact, and Mann-Whitney U tests.
  
  
  RESULTS
  Fifty-three patients with 67 FDPs (36 zirconia-ceramic, 31 metal-ceramic) were examined after a mean observation period of 40.3 +/- 2.8 months. Six patients with 9 FDPs were lost to follow-up. The survival of both kinds of FDPs was 100%. No significant differences regarding the technical and biologic outcomes were found. Minor chipping of the veneering ceramic was found in 25% of the zirconia-ceramic and 19.4% of the metal-ceramic FDPs. Extended fracturing of the veneering ceramic occurred solely in zirconia-ceramic FDPs (C: 8.6%, D: 2.8% [USPHS criteria]). Few biologic complications were found. Both types of FDPs rendered the same mean values for the biologic parameters (mean PPD, PCR, and BOP for zirconia-ceramic FDPs = 2.4 +/- 0.3, 0.1 +/- 0.1, and 0.3 +/- 0.2, respectively; mean PPD, PCR, and BOP for metal-ceramic FDPs = 2.4 +/- 0.3, 0.1 +/- 0.1, and 0.3 +/- 0.2, respectively).
  
  
  CONCLUSIONS
  Zirconia-ceramic FDPs exhibited a similar survival rate to metal-ceramic FDPs at 3 years of function.
authors.affiliation: Clinic for Fised and Removable Prosthodontics and Dental Material Science, Center for Dental and Oral Medicina, University of Zürich, Zürich, Switzerland. irena.sailer@zzmk.uzh.ch
authors.forename: Irena
authors.initials: I
authors.lastname: Sailer
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Gottnerb
authors.forename: Sarah
authors.initials: S
authors.lastname: Kanelb
authors.forename: Christoph Han Franz
authors.initials: CH
authors.lastname: Hammerle
mesh_terms: D001641:Bicuspid; D003776:Dental Porcelain; D003801:Dental Veneers; D003779:Denture Design; D003830:Denture, Partial, Fixed; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D016876:Metal Ceramic Alloys; D008875:Middle Aged; D008963:Molar; D019231:Tooth Preparation, Prosthodontic; D015040:Zirconium
chemical_list: D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide