title: Evaluation of Zirconia-Based All-Ceramic Single Crowns and Fixed Dental Prosthesis on Zirconia Implants: 5-Year Results of a Prospective Cohort Study.
abstract: OBJECTIVE
  The objective of this 5-year cohort investigation was to determine the survival and success rate of all-ceramic reconstructions on zirconia oral implants.
  
  
  METHODS
  Ninety-three patients received 122 one-piece zirconia implants. One hundred seventeen implants were restored with 63 single crowns (SCs) and 27 three-unit bridges (fixed dental prostheses, FDPs) fabricated using zirconia frameworks (Procera(®) Zirconia, Nobel Biocare(®), Göteborg, Sweden) hand-layered with a silicate ceramic (NobelRondo(™) Zirconia, Nobel Biocare(®)). With any occurrence of chipping regarded as an event, Kaplan-Meier success curves were plotted. Covariates (gender, location, manufacturing date) were estimated by the use of log-rank tests.
  
  
  RESULTS
  Eighty-nine patients received prosthetic reconstructions. Sixty-three of them were seen at the 5-year follow-up, with a mean observation time of 58.2 months (47 patients with SCs, 16 patients with FDPs). Reasons for the decreasing number of patients at the follow-up sessions included dropouts due to implant loss (n = 21), moving (n = 3), missed appointments (n = 1), and severe illness (n = 1). Over half of the SCs (57.2%) and 38% of the FDPs were successful after an observation time of 5 years (overall success rate of 51.7%). The performed log-rank tests revealed no statistically significant differences for the success curves regarding the above-mentioned covariates. Among the 63 restorations that completed the study, 11 of 47 SCs and one of 16 FDPs had to be replaced due to the severity of the observed chipping. This results in survival rates of 76.6% for the SCs and 93.8% for the FDPs. No framework fractures or decementations were observed in any group.
  
  
  CONCLUSIONS
  Hand-layering of zirconia-based SCs and FDPs with NobelRondo(™) Zirconia restoring one-piece zirconia implants did not show acceptable survival and success rates. Meanwhile, the material has been recalled from the market. It is advised that new materials should undergo adequate preclinical evaluation before coming to the market.
authors: Clinic of Prosthodontics, School of Dentistry, Albert-Ludwigs-University, Freiburg, Germany.
authors: Benedikt Christopher
authors: BC
authors: Spies
authors: Center for Medical Biometry and Medical Informatics, Medical Center - University of Freiburg, Freiburg, Germany.
authors: Susanne
authors: S
authors: Stampf
authors: Clinic of Prosthodontics, School of Dentistry, Albert-Ludwigs-University, Freiburg, Germany.
authors: Ralf-Joachim
authors: RJ
authors: Kohal
mesh_terms: D000328:Adult; D000368:Aged; D002516:Ceramics / Q000032:analysis*; D003442:Crowns; D003776:Dental Porcelain / Q000032:analysis; D003830:Denture, Partial, Fixed; D005260:Female; D006801:Humans; D008297:Male; D016876:Metal Ceramic Alloys / Q000032:analysis; D008875:Middle Aged; D011446:Prospective Studies; D014025:Titanium / Q000032:analysis; D055815:Young Adult; D015040:Zirconium / Q000032:analysis*
chemical_list: D016876:Metal Ceramic Alloys; C077451:Procera; D003776:Dental Porcelain; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide
keywords: all-ceramic; chipping; clinical study; zirconia implants