title: Electroplated telescopic retainers with zirconia primary crowns: 3-year results from a randomized clinical trial.
abstract: OBJECTIVE
  The objective of the study was to investigate the clinical outcome for electroplated telescopic removable dental prostheses (E-RDPs) with zirconia primary crowns.
  
  
  METHODS
  Sixty E-RDPs, with primary crowns manufactured from either cobalt-chromium alloy or zirconia, were fabricated for 56 participants. Electroplating was used to produce gold copings directly on the telescopic primary crowns. These copings were bonded intra-orally to the prosthesis framework. After 36 months, prosthesis survival and number of complications were assessed. Statistical analysis was performed by the use of Kaplan-Meier modeling and the log-rank test.
  
  
  RESULTS
  Survival of the E-RDPs, 96.4% after 3 years, was identical in both groups. The need for aftercare was high but not significantly different: technical complications were observed for 37% and 42.9% of the prostheses for the zirconia and cobalt-chromium alloy primary crowns, respectively. Fracture of composite veneer was the most frequent complication (59.1%). The incidence of fractured abutment teeth, decementation, and endodontic problems was 7.9% in the zirconia group and 14% in the control group. The majority of abutment-level complications were treated restoratively. A significant difference was found for maximum probing depth at the abutment teeth: In the zirconia group, it decreased by 0.2 mm, whereas it increased by 0.8 mm in the control group (p = 0.04).
  
  
  CONCLUSIONS
  After 3 years of observation, survival of zirconia E-RDPs was favorable and comparable with that of established double-crown-retained prostheses. Further studies must clarify whether there are benefits of zirconia primary crowns for periodontal health.
  
  
  CONCLUSIONS
  Although these results encourage the use of zirconia primary crowns, more research is necessary to reduce the number of complications observed for secondary telescopic crowns, for example, failure of the veneer.
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. Sebastian.Schwindling@med.uni-heidelberg.de.
authors.forename: Franz Sebastian
authors.initials: FS
authors.lastname: Schwindling
authors.affiliation: Private practice, Landshut, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Lehmann
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Sophia
authors.initials: S
authors.lastname: Terebesi
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Corcodel
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zenthöfer
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Rammelsberg
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stober
mesh_terms: D000328:Adult; D000368:Aged; D002858:Chromium Alloys / Q000737:chemistry*; D003442:Crowns; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D003832:Denture, Partial, Removable; D004595:Electroplating; D005260:Female; D006047:Gold Alloys / Q000737:chemistry*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
chemical_list: D002858:Chromium Alloys; D006047:Gold Alloys; D015040:Zirconium; C028541:zirconium oxide
keywords: Cobalt–chromium; Electroplating; Prosthetic dentistry; Removable dental prostheses; Zirconia