title: Effect of fibre post length and adhesive strategy on fracture resistance of endodontically treated teeth after fatigue loading.
abstract: OBJECTIVE
  To evaluate the effect of the length of fibre-posts(1) and type of adhesive cement(2) on the fracture resistance of endodontically treated teeth, after fatigue loading.
  
  
  METHODS
  Eighty extracted upper pre-molars were sectioned at the CEJ and endodontically treated. After 24 h of water storage at 37°C, RelyX Posts (3M-ESPE) were cemented with Panavia F 2.0 (Kuraray) or RelyX Unicem (3M-ESPE). A standardized composite core was built. Specimens were divided into four groups depending on the post-core ratio: (A) 2/1 (control); (B) 3/2; (C) 1/1 (small diameter); (D) 1/1(large diameter) and submitted to 1,200,000 cycles using a chewing simulator (Willytech). Immediately afterwards, all specimens that survived fatigue loading were fractured using a universal loading device (Micro-tester, Instron). Data were analysed with ANOVA.
  
  
  RESULTS
  Four percent of the specimens failed during fatigue loading. The length of the post into the root affected the fracture resistance. The statistical outcome varied according to the inclusion of specimens failed during fatigue loading. However, the control group always had the lowest fracture resistance. The type of adhesive cement did not affect the fracture resistance. A prevalence of not-repairable failures was observed in specimens restored with the longest posts, whilst shorter posts led to more repairable failures.
  
  
  CONCLUSIONS
  Shortening the post length and the ensuing preservation of more tooth structure, offer the potential for reparability through an in-built fail safe mechanism and may thus reduce the occurrence of catastrophic failures.
authors.affiliation: Leuven BIOMAT Research Cluster, Department of Prosthetic Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Belgium. francesca.zicari@med.kuleuven.be
authors.forename: F
authors.initials: F
authors.lastname: Zicari
authors.forename: B
authors.initials: B
authors.lastname: Van Meerbeek
authors.forename: R
authors.initials: R
authors.lastname: Scotti
authors.forename: I
authors.initials: I
authors.lastname: Naert
mesh_terms: D001641:Bicuspid / Q000503:physiopathology; D001732:Bite Force; D002484:Cementation / Q000379:methods*; D003188:Composite Resins / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005898:Glass / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation*; D019279:Resin Cements / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014082:Tooth Fractures / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000503:physiopathology / Q000628:therapy*; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C500742:ED Primer II; D008689:Methacrylates; C438843:Panavia-Fluoro; C483701:Rely X Unicem; D019279:Resin Cements; C009753:fiberglass; D014867:Water