title: The effect of load cycling on the nanoleakage of dentin bonding systems.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effects of load cycling on nanoleakage of occlusal flat surface or cervical restorations bonded with three self-etching priming systems and a single bottle system.
  
  
  METHODS
  The dentin bonding systems used in this study were Clearfil SE Bond, Unifil Bond, Prompt L-Pop and Single Bond. Flat occlusal dentin surfaces and cervical cavities from extracted human molars were bonded with one of the dentin bonding systems. After load cycling of 90N for 5000 cycles, samples were immersed in a 50% w/v solution of silver nitrate for 24h, and exposed to photodeveloping solution for 8h. Specimens were sectioned, mounted on stubs, carbon-coated and observed in a Field Emission-SEM using backscattered electron mode. One-way ANOVA was used for statistical analysis of the leakage scores.
  
  
  RESULTS
  FE-SEM images showed that samples subjected to load cycling had leakage patterns similar to non-load-cycled samples for all dentin bonding systems. Load cycling did not affect leakage lengths in any system. Prompt L-Pop had greater silver deposition and leakage score than the other systems.
  
  
  CONCLUSIONS
  The dentin bonding systems tested were unable to prevent nanoleakage, and the extent of nanoleakage was not increased by load cycling.
authors.affiliation: School of Dental Science, The University of Melbourne, Melbourne, Victoria 3000, Australia. h.li3@pgrad.unimelb.edu.au
authors.forename: Heping
authors.initials: H
authors.lastname: Li
authors.forename: Michael F
authors.initials: MF
authors.lastname: Burrow
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Tyas
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification*; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements / Q000737:chemistry; D016622:Silver Staining; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D019237:Tooth Cervix / Q000648:ultrastructure; D016474:Weight-Bearing
chemical_list: C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C408584:Prompt L-Pop; D019279:Resin Cements; C407402:Unifil Bond; C115612:single bond; C074741:Silux Plus; D017438:Bisphenol A-Glycidyl Methacrylate