title: A randomized, prospective, open-ended clinical trial of zirconia fixed partial dentures on teeth and implants: interim results.
abstract: OBJECTIVE
  The aim of this randomized controlled clinical trial was to compare the outcomes of zirconia crowns and fixed partial dentures (FPDs) supported by teeth or implants.
  
  
  METHODS
  Patients were recruited based on inclusion/exclusion criteria, and 59 eligible subjects were assigned randomly to treatment by one of four zirconia systems (Cercon, ZirkonZahn, Lava, and Katana). One hundred seven single-tooth and 160 three- to six-unit FPDs were fabricated on teeth and implants and cemented using composite resin cement. Californian Dental Association (CDA) quality evaluation, Plaque Index, and Gingival Index scores were recorded, and radiographic assessment of the restorations was performed using periapical and panoramic radiographs at baseline and annually up to 4 years.
  
  
  RESULTS
  Five failures (1.9%) were recorded. The 4-year Kaplan-Meier survival probabilities of FPDs were higher than those of single-tooth restorations (P = .046). The highest survival probability for crowns was observed for Katana and the lowest for Cercon (P < .05). For FPDs, the survival probabilities of Lava restorations were similar to those of Cercon but lower than those of ZirkonZahn and Katana (P < .05). The 4-year survival probabilities of implant- and tooth-supported crowns were comparable (P = .182). Regarding CDA ratings, the slight marginal discrepancy scores for the Cercon restorations were higher than for the other systems at 1 year (P < .05). In FPDs, 94.5% of Katana FPDs had slight or gross color mismatch scores, and the difference between color and surface ratings among zirconia systems was significant (P < .05). FPDs had better periodontal scores than crowns over the 4-year observation period (P < .05).
  
  
  CONCLUSIONS
  The 4-year interim results of this study suggest that zirconia systems used to fabricate FPDs have predictably high survival rates on teeth and implants and may exhibit differences, particularly in terms of mechanical failures, marginal adaptation, and color matching.
authors.affiliation: Department of Prosthodontics, Ordu University, Ordu, Turkey.
authors.forename: Elcin
authors.initials: E
authors.lastname: Sagirkaya
authors.forename: Serdar
authors.initials: S
authors.lastname: Arikan
authors.forename: Burak
authors.initials: B
authors.lastname: Sadik
authors.forename: Cankat
authors.initials: C
authors.lastname: Kara
authors.forename: Durdu
authors.initials: D
authors.lastname: Karasoy
authors.forename: Murat
authors.initials: M
authors.lastname: Cehreli
mesh_terms: D000328:Adult; D002484:Cementation; D003442:Crowns; D000044:Dental Abutments; D018772:Dental Marginal Adaptation; D003774:Dental Plaque Index; D003776:Dental Porcelain; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003779:Denture Design; D003830:Denture, Partial, Fixed; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D010512:Periodontal Index; D011446:Prospective Studies; D016037:Single-Blind Method; D012953:Societies, Dental; D014070:Tooth / Q000502:physiology; D019231:Tooth Preparation, Prosthodontic; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide