title: Effects of cyclic loading on selected post-and-core systems.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the resistance of selected post-and-core systems to fatigue testing.
  
  
  METHODS
  A fatigue-testing machine and data acquisition software were developed for this in vitro test. Pulpless mandibular second premolars were treated with three different types of post-and-core system: (1) two different prefabricated posts with amalgam cores, (2) the same two prefabricated posts with resin composite cores, and (3) cast post and cores, which served as the control group. The fatigue-testing machine applied alternating buccal and lingual forces to the core until lateral movement of 0.0025 inches (63.5 microns) was detected by a transducer contacting the surface of the core. This criterion represented initial cement failure.
  
  
  RESULTS
  Although groups using the resin composite core material exhibited a higher number of cycles prior to failure, there was no statistically significant difference between the different post-and-core systems.
  
  
  CONCLUSIONS
  All of the post-and-core systems that were tested may be acceptable for restoring endodontically treated teeth.
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D016009:Chi-Square Distribution; D003188:Composite Resins; D003723:Dental Amalgam; D006801:Humans; D008334:Mandible; D008422:Materials Testing / Q000295:instrumentation; D011176:Post and Core Technique / Q000295:instrumentation*; D013718:Tensile Strength