title: Microtensile bond strength of dual-polymerizing cementing systems to dentin using different polymerizing modes.
abstract: BACKGROUND
  The effectiveness of bond strength using dual-polymerizing cementing systems ([DCSs] defined as the combination of dual-polymerizing bonding agents and resin cements) used with indirect restorations has not been evaluated when used solely with the autopolymerizing mode.
  
  
  OBJECTIVE
  This study evaluated the in vitro microtensile bond strength (MTBS) of fourth- and fifth-generation DCSs with indirect composite restorations either light polymerized or autopolymerized.
  
  
  METHODS
  Occlusal dentin surfaces of 48 human third molars were exposed and flattened. Teeth were assigned to 8 groups (n=6) according to the DCS and polymerizing modes: All-Bond2/Duolink (AB2), Optibond/Nexus2 (OPT), Bond1/Lute-it (B1), and Optibond Solo Dual Cure/Nexus2 (SOLO). Bonding agents were applied to dentin surfaces and left in the unpolymerized state. Resin cements were applied to prepolymerized resin discs (2 mm thick/Z250), which were subsequently bonded to the dentin surfaces. The restored teeth were light polymerized according to manufacturers' instructions (PP/XL 3000) or allowed to autopolymerize (AP). Restored teeth were stored in water at 37 degrees C for 24 hours and were both mesio-distally and bucco-lingually sectioned to obtain multiple bonded beams (1.2 mm2 of cross-sectional area). Each specimen was tested in tension at a crosshead speed of 0.6 mm/min until failure. Data (MPa) were analyzed by 2-way analysis of variance and the Tukey post hoc test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy.
  
  
  RESULTS
  The mean (SD) MTBS values (MPa) were: AB2/PP: 36.9 (6.5); AB2/AP: 32.7 (7.3); B1/PP: 38.2 (7.0); B1/AP: 13.0 (4.2); SOLO/PP: 33.2 (7.2); SOLO/AP: 23.4 (3.4); OPT/PP: 30.8 (7.5); OPT/AP: 13.1 (5.8). The AP groups showed significantly lower MTBS than the PP groups (P<.0001), except for AB2, which showed no difference between polymerization modes (P=.2608).
  
  
  CONCLUSIONS
  The autopolymerizing mode of some dual-polymerizing cement systems may not be effective in promoting bond strength.
authors.affiliation: Department of Restorative Dentistry, Piracicaba School of Dentistry, University of Campinas, Piracicaba, Brazil.
authors.forename: Cesar A G
authors.initials: CA
authors.lastname: Arrais
authors.forename: Marcelo
authors.initials: M
authors.lastname: Giannini
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Rueggeberg
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D000704:Analysis of Variance; D001840:Dental Bonding / Q000379:methods*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000379:methods; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008027:Light; D008964:Molar, Third / Q000737:chemistry*; D013718:Tensile Strength
chemical_list: D017220:Dentin-Bonding Agents