title: Fracture toughness of conventional, resin-modified glass-ionomer and composite luting cements.
abstract: OBJECTIVE
  This study was conducted to determine if significant differences existed between the fracture toughness of three types of luting cement, and, if the method of mixing conventional glass-ionomer luting cements, hand-mixed or mechanically mixed, influenced the value obtained.
  
  
  METHODS
  Three types of luting cement were investigated: conventional glass-ionomer cement (two handmixed and two capsulated cements, KetacCem, Fuji I and KetacCem Maxicap, Fuji Cap I), a resin-modified glass-ionomer cement (Vitremer Luting Cement) and a resin composite cement (Scotchbond Resin Cement). Eleven specimens of each of the six cements were fabricated to determine the plane strain fracture toughness using the chevron notch short rod technique. After seven days the specimens were loaded in a water bath, at a crosshead speed of 4 microns/s and the fracture toughness values calculated.
  
  
  RESULTS
  ANOVA indicated significant differences between the cements (p < 0.0001) and each cement was compared with all others using Fishers PSLD test (p < 0.05). The rank order of results from highest fracture toughness value to lowest (mean +/- s.d.) was Scotchbond Resin Cement (1.31 +/- 0.17), Vitremer Luting Cement (1.08 +/- 0.1), Fuji Cap I (0.37 +/- 0.04), KetacCem Maxicap (0.37 +/- 0.05), Fuji I (0.34 +/- 0.04), KetacCem (0.27 +/- 0.03).
  
  
  CONCLUSIONS
  Of the cements tested, the resin composite cement is most likely to resist clinical failure by cement cohesive failure.
authors.affiliation: Divison of Restorative Dentistry School of Clinical Dentistry, Queen's University of Belfast, Royal Victoria Hospital, UK. c.mitchell@qub.ac.uk
authors.forename: C A
authors.initials: CA
authors.lastname: Mitchell
authors.forename: W H
authors.initials: WH
authors.lastname: Douglas
authors.forename: Y S
authors.initials: YS
authors.lastname: Cheng
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D004548:Elasticity; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008277:Magnesium Oxide; D008422:Materials Testing; D011076:Polycarboxylate Cement; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013718:Tensile Strength; D015034:Zinc Oxide
chemical_list: D003188:Composite Resins; D005899:Glass Ionomer Cements; D011076:Polycarboxylate Cement; D019279:Resin Cements; C084550:Vitremer; C084541:Fuji glass-ionomer lining cement; D008277:Magnesium Oxide; C040235:Ketac-cem; C041330:Scotchbond; D015034:Zinc Oxide