Effects of cyclic loading on selected post-and-core systems

Objective: The purpose of this study was to evaluate the resistance of sele cted post-and-core systems to fatigue testing. Method and materials: A fati gue-testing machine and data acquisition software were developed for this i n vitro test Pulpless mandibular second premolars were treated with three d ifferent types of post-and-core system:(1) two different prefabricated post s with amalgam cores, (2) the same two prefabricated posts with resin compo site 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 mu m) was detecte d by a transducer contacting the surface of the core. This criterion repres ented initial cement failure. Results: Although groups using the resin comp osite core material exhibited a higher number of cycles prior to failure, t here was no statistically significant difference between the different post -and-core systems. Conclusion: All of the post-and-core systems that were t ested may be acceptable for restoring endodontically treated teeth.