title: Fatigue behavior of resin composites in aqueous environments.
abstract: OBJECTIVE
  Interaction between mechanical and chemical fatigue of resin composites was investigated.
  
  
  METHODS
  Fatigue fracture resistance of composites after (1) water immersion and under (2) dry and (3) aqueous conditions was analyzed using a fatigue crack propagation test. The characteristics of fatigue crack propagation were expressed as the correlation between the fatigue crack growth rate (da/dN) and stress intensity factor range (DeltaK) and by the fatigue crack growth threshold (DeltaKth). Following the fatigue test, a fractographic examination was performed by scanning electron microscopy.
  
  
  RESULTS
  Contrary to common perception, fatigue crack propagation was retarded under aqueous conditions but accelerated after water immersion. In addition, fatigue cracks detoured around inorganic macro-fillers, but penetrated organic fillers.
  
  
  CONCLUSIONS
  It was concluded that the inverse effects of water on fatigue resistance of composites are dependent on the experimental conditions. Moreover, inorganic macro-fillers were shown to be functional in retarding fatigue cracks in composites.
authors.affiliation: Osaka University Graduate School of Dentistry, Department of Restorative Dentistry and Endodontology, 1-8, Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Takeshige
authors.forename: Y
authors.initials: Y
authors.lastname: Kawakami
authors.forename: M
authors.initials: M
authors.lastname: Hayashi
authors.forename: S
authors.initials: S
authors.lastname: Ebisu
mesh_terms: D003188:Composite Resins / Q000737:chemistry; D003799:Dental Stress Analysis; D019544:Equipment Failure Analysis; D006868:Hydrolysis; D007101:Immersion; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D012822:Silicon Dioxide; D013997:Time Factors; D014867:Water; D015040:Zirconium
chemical_list: D003188:Composite Resins; C083568:Z100 composite resin; D014867:Water; C092420:Clearfil Photo Posterior; C091838:Clearfil Photo Anterior; D012822:Silicon Dioxide; D015040:Zirconium