title: Clinical performance of conical and electroplated telescopic double crown-retained partial dentures: a randomized clinical study.
abstract: OBJECTIVE
  The aim of this study was to quantify and compare the clinical performance of cast conical double crown-retained removable partial dentures (C-RPDs) and electroplated double crown-retained removable partial dentures (EP-RPDs).
  
  
  METHODS
  A total of 60 RPDs were placed in 54 patients. Participants were randomly assigned to two study groups (C-RPD and EP-RPD). Altogether, 217 abutment teeth were provided with double crowns. Patients were reexamined after 6, 12, 24, and 36 months. The main endpoints were the survival times of RPDs and abutment teeth; secondary endpoints included failure of the facing, loss of cementation of primary crowns, and postprosthetic endodontic treatment. Chi-square tests were used to evaluate group differences regarding characteristics of patients and RPDs. Survival differences were investigated using the log-rank test and Cox regression; secondary endpoints were assessed using logistic regression.
  
  
  RESULTS
  After 36 months, survival was 100% for C-RPDs and 93.3% for EP-RPDs. Cumulative survival for abutment teeth was 97.3% (C-RPDs) and 96.2% (EP-RPDs). Survival differences between the two study groups did not reach statistical significance. The survival of abutments depended on tooth vitality and position; for example, the hazard of tooth loss was 676% higher for nonvital teeth. No differences were found between study groups regarding facing failure, decementation of primary crowns, or postprosthetic endodontic treatment.
  
  
  CONCLUSIONS
  Vitality and position are important to the survival of teeth supporting partial dentures. Longer follow-up and larger patient collectives are needed to evaluate possible differences between cast conical and electroplated telescopic double crown-retained partial dentures.
authors.affiliation: Department of Prosthodontics, University Hospital, 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: Joachim
authors.initials: J
authors.lastname: Beck-Mussoter
authors.forename: Anne-Christiane
authors.initials: AC
authors.lastname: Seche
authors.forename: Franziska
authors.initials: F
authors.lastname: Lehmann
authors.forename: Juanita
authors.initials: J
authors.lastname: Koob
authors.forename: Peter
authors.initials: P
authors.lastname: Rammelsberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003442:Crowns; D000044:Dental Abutments; D003735:Dental Casting Technique; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003781:Denture Retention / Q000295:instrumentation / Q000379:methods; D003828:Denture, Overlay; D003832:Denture, Partial, Removable; D004595:Electroplating; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies