title: Fatigue of the resin-dentin interface: a new approach for evaluating the durability of dentin bonds.
abstract: There are concerns regarding the longevity of resin composite restorations and the clinical relevance of in vitro bond strength testing to the durability of dentin bonds in vivo.
  
  
  OBJECTIVE
  The objectives of this investigation were to: (1) develop a new method of experimental evaluation for quantifying the durability of dentin bonds, (2) apply this method to characterize the interfacial strength of a selected commercial system under both monotonic and cyclic loading, and (3) distinguish mechanisms contributing to the interface degradation and failure.
  
  
  METHODS
  A new method for fatigue testing the resin-dentin interface was developed based on a four-point flexure arrangement that includes two identical bonded interfaces. Cyclic loading of specimens comprised of coronal dentin bonded to a commercial resin composite and controls of resin composite was performed to failure within a hydrated environment. Scanning electron microscopy and nanoscopic dynamic mechanical analysis were used to evaluate failure mechanisms.
  
  
  RESULTS
  The fatigue strength of the resin-dentin interface was significantly lower (p≤0.0001) than that of the resin composite and reported for dentin over the entire finite life regime. Defined at 1×10(7) cycles, the apparent endurance limit of the resin-dentin interface was 13MPa, in comparison to 48MPa and 44MPa for the resin composite and dentin, respectively. The ratio of fully reversed endurance limit to ultimate strength of the interface (0.26) was the lowest of the three materials.
  
  
  CONCLUSIONS
  The proposed approach for characterizing the fatigue strength of resin-dentin bonds may offer new insights concerning durability of the bonded interface.
authors: Adhesive Dentistry Research Group, Department of Cariology, Institute of Dentistry, University of Turku, Turku, Finland.
authors: Mustafa Murat
authors: MM
authors: Mutluay
authors: Mobin
authors: M
authors: Yahyazadehfar
authors: Heonjune
authors: H
authors: Ryou
authors: Hessam
authors: H
authors: Majd
authors: Dominic
authors: D
authors: Do
authors: Dwayne
authors: D
authors: Arola
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003804:Dentin / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements