title: Fatigue susceptibility of an endodontic fibre post material.
abstract: OBJECTIVE
  To evaluate effects of ageing and fatigue on the elastic modulus and short-beam shear strength of a quartz fibre/epoxy resin post material.
  
  
  METHODS
  Cylindrical specimens (25 × 2.2 mm) were made. Elastic moduli were dynamically measured before immersion in water; after immersion in water; periodically during storage in water for up to 7 years; periodically during thermal cycling in water for up to 10 000 cycles to produce thermo-mechanical fatigue; and periodically during boiling in water for up to 100 h. After ageing, the specimens underwent short-beam shear strength testing.
  
  
  RESULTS
  Elastic modulus was significantly decreased by thermal cycling and by immersion in boiling water, but not by water storage. Short-beam shear strength was profoundly decreased by all three ageing processes. Short-beam shear strength was much more sensitive than elastic modulus to the ageing or fatigue processes applied in this study.
  
  
  CONCLUSIONS
  A representative endodontic fibre post material was susceptible to a variety of ageing and fatigue processes. The effects of ageing and fatigue had a more pronounced impact on short-beam shear strength than on elastic modulus. The effects of boiling in water and thermal cycling in water were considerably larger than those of simple storage in water.
authors.affiliation: School of Dentistry, University of California, Los Angeles, CA, USA.
authors.forename: J V B
authors.initials: JV
authors.lastname: Barbizam
authors.forename: S N
authors.initials: SN
authors.lastname: White
mesh_terms: D004548:Elasticity; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation*; D033081:Shear Strength
keywords: ageing; elastic modulus; endodontics; fatigue strength; fibre post; shear