title: Bi-layered zirconia/fluor-apatite bridges supported by ceramic dental implants: a prospective case series after thirty months of observation.
abstract: OBJECTIVE
  The aim of this study was to determine the success and survival rate of all-ceramic bi-layered implant-supported three-unit fixed dental prostheses (IS-FDPs) 3 years after implant placement.
  
  
  METHODS
  Thirteen patients (seven males, six females; age: 41-78 years) received two one-piece ceramic implants (alumina-toughened zirconia) each in the region of the premolars or the first molar and were finally restored with adhesively cemented bi-layered zirconia-based IS-FDPs (3 in the maxilla, 10 in the mandible) composed of CAD/CAM-fabricated zirconia frameworks pressed-over with fluor-apatite glass-ceramic ingots. At prosthetic delivery and the follow-ups after 1, 2 and 3 years, the restorations were evaluated using modified United States Public Health Service (USPHS) criteria. Restorations with minor veneer chippings, a small-area occlusal roughness, slightly soundable restoration margins, minimal contour deficiencies and tolerable color deviations were regarded as success. In case of more distinct defects that could, however, be repaired to a clinically acceptable level, IS-FDPs were regarded as surviving. Kaplan-Meier plots were used for the success/survival analyses. To verify an impact on subjective patients' perceptions, satisfaction was evaluated by visual analog scales (VAS).
  
  
  RESULTS
  All patients were seen 3 years after implant installation. No IS-FDP had to be replaced, resulting in 100% survival after a mean observation period of 29.5 months (median: 30.7). At the 3-year follow-up, 7/13 IS-FDPs showed a veneer chipping, 13/13 an occlusal roughness and 12/13 minimal deficiencies of contour/color. Since six restorations showed a major chipping and/or a major occlusal roughness, the Kaplan-Meier success rate was 53.8%. However, patients' significantly improved perceptions of function, esthetics, sense, and speech at prosthetic delivery remained stable over time.
  
  
  CONCLUSIONS
  Bi-layered zirconia/fluor-apatite IS-FDPs entirely survived the observation period but showed a high frequency of technical complications. Nevertheless, the treatment highly satisfied patients' expectations.
authors.affiliation: Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Freiburg, Germany. benedikt.spies@uniklinik-freiburg.de.
authors.forename: Benedikt Christopher
authors.initials: BC
authors.lastname: Spies
authors.affiliation: Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Freiburg, Germany.
authors.forename: Siegbert
authors.initials: S
authors.lastname: Witkowski
authors.affiliation: Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Freiburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Butz
authors.affiliation: Medical Center - University of Freiburg, Center for Medical Biometry and Medical Informatics, Institute for Medical Biometry and Statistics, Freiburg, Germany.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Vach
authors.affiliation: Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Freiburg, Germany.
authors.forename: Ralf-Joachim
authors.initials: RJ
authors.lastname: Kohal
mesh_terms: D000328:Adult; D000368:Aged; D001031:Apatites; D002516:Ceramics; D003738:Dental Cements; D015921:Dental Implants; D003764:Dental Materials; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D016876:Metal Ceramic Alloys; D008875:Middle Aged; D011446:Prospective Studies; D015040:Zirconium
chemical_list: D001031:Apatites; D003738:Dental Cements; D015921:Dental Implants; D003764:Dental Materials; D016876:Metal Ceramic Alloys; C023506:Glass ceramics; D015040:Zirconium; C025105:fluorapatite; C028541:zirconium oxide
keywords: CAD-CAM; ceramics; cohort study; dental implant; dental porcelain; fixed bridge; zirconia