title: Up to 17-year controlled clinical study on post-and-cores and covering crowns.
abstract: OBJECTIVE
  The aim of this long-term follow-up was to collect up to 17-year survival data of different metal post-and-core restorations with a covering crown.
  
  
  METHODS
  At initiation of the study, a controlled clinical trial, single tooth was provided with an artificial covering crown, by 18 operators. Restorations under investigation were the post-and-core restorations: cast post-and-core restorations, prefabricated metal post and resin composite core restorations, and post-free all-composite core restorations. Before treatment allocation, the recipient tooth was categorized according to the expected dentin height after tooth preparation. A tooth was assessed to have "substantial dentin height" (Trial 1) or "minimal dentin height" (Trial 2). The study sample consisted of 257 patients that received 307 core restorations. The performance of the restorations was based on data collected from the files of the current dentists monitoring the oral health of the patients. The survival probability was analyzed at different levels: on the restoration level (S(R)), and on the level of the tooth carrying the restoration (S(T)). Kaplan Meier analyses were used to compare survival probabilities.
  
  
  RESULTS
  "Type of post-and-core restoration" showed no influence on the survival probability (at both levels) in both trials (P-value>0.05). The 17-year survival rates at restoration level varied from 71% to 80%, and at tooth level from 83% to 92%.
  
  
  CONCLUSIONS
  The results of this study showed no difference in survival probabilities among different core restorations under a covering crown of endodontically treated teeth. The preservation of substantial remaining coronal tooth structure seems to be critical to the long-term survival of endodontically treated crowned teeth.
authors: Department of Oral Function and Prosthetic Dentistry, College of Dental Science, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. w.fokkinga@dent.umcn.nl
authors: Wietske A
authors: WA
authors: Fokkinga
authors: Cees M
authors: CM
authors: Kreulen
authors: Ewald M
authors: EM
authors: Bronkhorst
authors: Nico H J
authors: NH
authors: Creugers
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003442:Crowns / Q000706:statistics & numerical data*; D019232:Dental Restoration Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011176:Post and Core Technique / Q000706:statistics & numerical data*; D018709:Statistics, Nonparametric; D016019:Survival Analysis