title: Survival time of cast post and cores: a 10-year retrospective study.
abstract: OBJECTIVE
  The aim of this retrospective, longitudinal study was to examine the survival time of custom-fabricated, cast post and cores and to evaluate, which covariates influence the risk of failures over a period of up to 10 years based on a large patient collective.
  
  
  METHODS
  The files of 565 patients, who had been fitted with a total of 802 custom-fabricated, cast post and cores using a standardised technique, were analysed. The following parameters were used in the evaluation: age of the post and cores, fabrication technique (direct, indirect), type of prosthetic restoration, location (upper, lower jaw), type of tooth (anterior, premolar, molar), number of root posts, luting material, post and core alloy and cause of failure. The survival probability was assessed using Kaplan-Meyer analysis. Cox regression was used to assess the risk of failure and identify possible covariates.
  
  
  RESULTS
  The average survival time of the post and cores was 7.3 years. The cumulative failure rate was 11.2%. The most common complication was loss of retention of the post and cores. High-gold-content posts had a lower risk of failure than posts made from semi-precious alloy. The type of restoration fitted had a significant influence on the survival probability.
  
  
  CONCLUSIONS
  Post and cores custom-fabricated using a standardised fabrication technique have a good long-term prognosis. The most common cause of failure is loss of retention. The durability of posts with low friction at the try-in stage cannot be compensated for by using glass ionomer cement as the luting material.
authors.affiliation: Department of Prosthetic Dentistry, Justus-Liebig-University, Schlangenzahl 14, 35392 Giessen, Germany. markus.balkenhol@dentist.med.uni-giessen.de
authors.forename: Markus
authors.initials: M
authors.lastname: Balkenhol
authors.forename: Bernd
authors.initials: B
authors.lastname: Wöstmann
authors.forename: Christian
authors.initials: C
authors.lastname: Rein
authors.forename: Paul
authors.initials: P
authors.lastname: Ferger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003722:Dental Alloys / Q000737:chemistry*; D019232:Dental Restoration Failure; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011176:Post and Core Technique / Q000295:instrumentation*
chemical_list: D003722:Dental Alloys