title: Effect of storage media and time on the fracture toughness of resin-based luting cements.
abstract: BACKGROUND
  Resin-based cements are brittle materials and the major shortcomings of these materials are manifested in their sensitivity to flaws and defects. Although various mechanical properties of resin luting cements have been described, few fracture toughness test data for resin-based luting cements using the short rod design have been published.
  
  
  METHODS
  Specimens were prepared from five resin luting cements. For each material a total of 36 disc-shaped specimens were prepared using a custom-made mould. Specimens were randomly divided into six groups of six, immersed in two solutions: distilled water and 0.01 mol/L lactic acid at 37 °C for 24 hours, 1 month or 3 months. The specimens were loaded using a universal testing machine. The maximum load at specimen failure was recorded and the K(Ic) (MPa. M 0.5) was calculated.
  
  
  RESULTS
  There was a relationship between material, storage solution and time (p < 0.05). Nexus 3 showed the highest K(Ic) followed by Panavia F, Calibra, Smart Cem2 and seT.
  
  
  CONCLUSIONS
  The fracture toughness of the resin luting cements was affected by both time and storage solution. Comparable fracture toughness of conventional resin cement and self-adhesive resin cements was observed.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: M R
authors.initials: MR
authors.lastname: Azar
authors.forename: R
authors.initials: R
authors.lastname: Bagheri
authors.forename: M F
authors.initials: MF
authors.lastname: Burrow
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003799:Dental Stress Analysis; D007101:Immersion; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry*; D013997:Time Factors
chemical_list: D003188:Composite Resins; D008689:Methacrylates; D019279:Resin Cements; D019344:Lactic Acid