title: Clinical evaluation of zirconia-based restorations on implants: a retrospective cohort study from the AIOP clinical research group.
abstract: OBJECTIVE
  The aim of this retrospective cohort study was to evaluate the clinical performance of zirconia-based implant-supported single crowns and fixed dental prostheses (FDPs) made by 15 members of the Italian Academy of Prosthetic Dentistry (AIOP) over a time period of up to 5 years.
  
  
  METHODS
  One hundred thirty-one patients were treated with a total of 210 zirconia-based single crowns and FDPs on implants in anterior and posterior regions. A cohort group with parafunctional habits was compared with patients without parafunctional habits according to the esthetic, functional, and biologic United States Public Health Service criteria modified by the FDI World Dental Federation.
  
  
  RESULTS
  The estimated cumulative survival (ECS) and standard error (SE) of all restorations on implants was 91.95% ± 1.39%, and the estimated cumulative success (ECSs) and SE was 88.37% ± 1.72%. The ECS of single crowns and FDPs was 91.25% ± 3.69% and 95.23% ± 2.28%, respectively, and the estimated cumulative success rates were 88.84% ± 2.05% and 87.96% ± 3.16%, respectively. Mechanical failures, including four zirconia core fractures, three hairline cracks, four chippings, and five delaminations of the ceramic veneering material, were recorded during a 1- to 5-year observation period. The odds ratio of 3.39 (95% confidence interval: 1.18 to 9.73) showed a moderate association between parafunction and failure.
  
  
  CONCLUSIONS
  Zirconiabased implant-supported restorations showed encouraging clinical results over a period of up to 5 years, but more clinical data are needed before these restorations can be considered a viable treatment alternative. Mechanical failures were primarily observed in patients with parafunctions.
authors.forename: Carlo
authors.initials: C
authors.lastname: Monaco
authors.forename: Mauro
authors.initials: M
authors.lastname: Caldari
authors.forename: Roberto
authors.initials: R
authors.lastname: Scotti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D003769:Dental Occlusion, Traumatic / Q000503:physiopathology; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003801:Dental Veneers; D003830:Denture, Partial, Fixed; D004955:Esthetics, Dental; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D017060:Patient Satisfaction; D012189:Retrospective Studies; D013499:Surface Properties; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide