title: 10-year clinical outcomes of fixed dental prostheses with zirconia frameworks.
abstract: OBJECTIVE
  The aim of this prospective clinical study was to assess the long-term clinical survival rate and the technical and biological complication rates of zirconia-based posterior FDPs.
  
  
  METHODS
  Forty-five patients in need of one or more posterior FDPs received 57 three- to five-unit zirconia-based FDPs. The frameworks were fabricated by means of a prototype computer-aided manufacturing (CAM) system (direct ceramic machining, DCM), first processing zirconia in the white stage. The frameworks were veneered with a prototype veneering ceramic.The FDPs were adhesively placed. At baseline, 6 months, and 1,2, 3, 5, 8 and 10 years of function, the FDPs were examined for technical and/or biological complications. Furthermore, the periodontal health of the abutment teeth (test) and untreated control teeth was analyzed. Statistical analysis was performed applying descriptive statistics, Kaplan-Meier survival and multiple mixed effects regression tests.
  
  
  RESULTS
  Twenty-one patients with 26 FDPs were examined at a mean observation time of 10.7 +/- 1.3 years. A total of 16 FDPs were lost to follow-up. Fifteen FDPs had to be replaced due to technical/biological complications; hence, the 10-year survival rate of the FDPs was 67%. Three framework fractures occurred, resulting in a 10-year survival rate for the zirconia frameworks of 91.5%. Chipping/fracture of the veneering ceramic was detected in 16 FDPs over 10 years (complication rate 32%). A significant correlation of the span of the FDPs and the incidence of chipping was observed: 4- and 5-unit FDPs had a 4.9 times higher probability for chipping than 3-unit FDPs. Marginal discrepancy/degradation was found in 90.7% of the FDPs over 10 years. At 11 of the FDPs (complication rate 27%), secondary caries occurred. No difference of the periodontal health was found around test and control teeth.
  
  
  CONCLUSIONS
  The zirconia frameworks exhibited very good long-term stability. However, the zirconia-based FDPs frequently exhibited problems such as marginal deficiency or chipping of the veneering ceramic. Both problems may be associated with the prototype status of the system.
authors.affiliation: Clinic for Fixed and Removable Prosthodontics and Dental Materials, School of Dental Medicine, University of Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Sax
authors.forename: C H F
authors.initials: CH
authors.lastname: Hämmerle
authors.forename: I
authors.initials: I
authors.lastname: Sailer
mesh_terms: D002484:Cementation; D017076:Computer-Aided Design; D003731:Dental Caries / Q000209:etiology; D003763:Dental Leakage / Q000150:complications; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003801:Dental Veneers; D003779:Denture Design; D003830:Denture, Partial, Fixed; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D016016:Proportional Hazards Models; D011446:Prospective Studies; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide