title: Surface characteristics of zirconia-based posterior restorations: clinical and scanning electron microscopic analysis.
abstract: OBJECTIVE
  The aim of this prospective clinical trial was to evaluate the performance of zirconia-based all-ceramic posterior fixed partial dentures (FPDs) after 4 years of clinical use.
  
  
  METHODS
  Fifteen patients who needed 3- or 4-unit posterior FPDs were enrolled in the study. One manufacturer fabricated all restorations, following established clinical protocols and using computer-aided design/computer-aided manufacturing technology and one veneering material. Survival and success were evaluated clinically. Impressions were taken immediately after definitive cementation and after 48 months. Gold-coated epoxy replicas of the restorations were analyzed with scanning electron microscopy (SEM). Surface alterations were also evaluated clinically.
  
  
  RESULTS
  After 48 months, the survival rate for the FPDs was 100%. Three restorations exhibited minor chipping, for a fracture rate of 20% after 4 years. Thirty (59%) of the 51 individual restoration units revealed clinically rough occlusal surfaces, a finding that was confirmed by SEM.
  
  
  CONCLUSIONS
  The placement of 3- and 4-unit zirconia-based posterior FPDs can be considered a reliable treatment modality for medium-term clinical use. However, surface alterations of the veneering ceramics were observed after 4 years and are of notable clinical concern.
authors.affiliation: Department of Prosthodontics, Friedrich-Alexander University of Erlangen-Nuremberg, Germany. johannes.schmitt@uk-erlangen.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Schmitt
authors.forename: Manfred
authors.initials: M
authors.lastname: Wichmann
authors.forename: Matthias
authors.initials: M
authors.lastname: Karl
authors.forename: Matthias
authors.initials: M
authors.lastname: Göllner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Lohbauer
authors.forename: Stefan
authors.initials: S
authors.lastname: Holst
mesh_terms: D000328:Adult; D000368:Aged; D002484:Cementation; D017076:Computer-Aided Design; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003801:Dental Veneers; D003779:Denture Design; D003830:Denture, Partial, Fixed; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D011446:Prospective Studies; D016628:Replica Techniques; D013499:Surface Properties; D016019:Survival Analysis; D016896:Treatment Outcome; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide