title: Electroplated and cast double crown-retained removable dental prostheses: 6-year results from a randomized clinical trial.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the clinical performance of removable dental prostheses (RDP) supported by either electroplated (EP-RDP) or cast (C-RDP) double crowns.
  
  
  METHODS
  Fifty-four participants received a total of 60 RDP. Two hundred and seventeen abutment teeth were provided with double crowns. The participants were randomly assigned to two groups (EP-RDP or C-RDP). Re-evaluations took place after 6 months and then once a year up to 6 years. Primary endpoint was survival time for RDP and abutment teeth; secondary endpoints were failure of facing, decementation of primary crown, and post-prosthetic endodontic treatment. T, U, and chi-squared tests were used to assess the homogeneity of the EP-RDP and C-RDP groups. Survival differences were analyzed with log-rank tests and Cox regression models; secondary endpoints were assessed by the use of logistic regression.
  
  
  RESULTS
  Six-year survival was 77 % for EP-RDP and 97 % for C-RDP. Cumulative survival of abutment teeth was 85 % for EP-RDP and 91 % for C-RDP; differences between survivals in the two groups did not reach statistical significance. Survival of abutment teeth depended on tooth vitality. Failures of facings, decementations, or post-prosthetic endodontic treatments were not different between groups.
  
  
  CONCLUSIONS
  To identify possible differences between different double crown systems, longer follow-up periods and/or larger numbers of patients are needed.
  
  
  CONCLUSIONS
  Survival of teeth supporting double crown-retained RDP is affected by their vitality. Clinical performance was acceptable for both RDP supported by electroplated or cast double crowns.
authors.affiliation: Department of Prosthodontics, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany, thomas.stober@med.uni-heidelberg.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stober
authors.forename: Justo Lorenzo
authors.initials: JL
authors.lastname: Bermejo
authors.forename: Anne-Christiane
authors.initials: AC
authors.lastname: Séché
authors.forename: Franziska
authors.initials: F
authors.lastname: Lehmann
authors.forename: Peter
authors.initials: P
authors.lastname: Rammelsberg
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bömicke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003442:Crowns; D000044:Dental Abutments; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D003832:Denture, Partial, Removable; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged