title: Clinical longevity of removable partial dentures retained by telescopic crowns: outcome of the double crown with clearance fit.
abstract: OBJECTIVE
  It was the aim of this study to investigate the long-term success of a telescopic crown system that can be used for both rigid and resilient support and to evaluate by means of a literature review whether the use of resilient support may be advantageous compared to other double crown systems when the restoration is placed on only a few remaining teeth.
  
  
  METHODS
  Patient records were used to evaluate 125 dentures (with 460 abutment teeth) based on the Marburg double crown system. The loss of abutment teeth, endodontic treatment, and fracture of the metallic framework were investigated with regard to the different types of denture support.
  
  
  RESULTS
  The probability that a patient would have kept all abutment teeth was 84% after 5 years and 66% after 10 years. No significant differences were found for the two groups "resilient support" (< or = three abutment teeth) and "rigid support" (> or = four abutment teeth). For abutment teeth with a double crown with clearance fit, the risk of loss was 4% after 5 years and 15% after 10 years for rigid support, and 10% and 24%, respectively, for resilient support. The risk of endodontic treatment was 7% after 5 years and 9% after 10 years for rigid support, and 3% and 7%, respectively, for resilient support. None of the denture frameworks showed a fracture during the observation period.
  
  
  CONCLUSIONS
  Removable partial dentures retained by double crowns with clearance fit and constructed without major or minor connectors provide good clinical longevity. The survival rates of abutment teeth were comparable to those reported in the literature for other double crown systems. There was no significant increase of the risk of abutment loss when the restoration was placed on three or fewer remaining teeth and the concept of resilient support was applied.
authors.affiliation: Department of Preclinical and Maxillofacial Prosthodontics, Marburg School of Dental Medicine, Philipps University, Marburg, Germany. wenz@mailer.uni-marburg.de
authors.forename: H J
authors.initials: HJ
authors.lastname: Wenz
authors.forename: K
authors.initials: K
authors.lastname: Hertrampf
authors.forename: K M
authors.initials: KM
authors.lastname: Lehmann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016001:Confidence Intervals; D003442:Crowns; D000044:Dental Abutments; D003722:Dental Alloys; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003779:Denture Design; D003781:Denture Retention; D003828:Denture, Overlay; D003832:Denture, Partial, Removable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011336:Probability; D012189:Retrospective Studies; D012307:Risk Factors; D012390:Root Canal Therapy; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013499:Surface Properties; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D003722:Dental Alloys