title: Prolonged exposure times of one-step self-etch adhesives on adhesive properties and durability of dentine bonds.
abstract: OBJECTIVE
  To evaluate the effect of prolonged exposure times on immediate and 6-month adhesive properties: degree of conversion (DC), nanoleakage (NL) and resin-dentine bond strength (μTBS) of three one-step self-etch adhesive systems (Adper Easy One [EO], Clearfil S(3) Bond [CS3] and Go [GO]).
  
  
  METHODS
  The adhesives were applied on exposed dentine surfaces of 90 human molars according to manufacturers' instructions and light polymerized for 10, 20, and 40 s at 600 mW/cm(2). Bonded teeth were sectioned to obtain stick-shaped specimens (0.8 mm(2)) and tested under tensile stress (0.5 mm/min) immediately (IM) or after 6 months of water storage. Two bonded sticks from each tooth at each storage time interval were analysed by SEM for NL evaluation. The in situ DC was evaluated by micro-Raman spectroscopy. Data were analysed by appropriate ANOVA and Tukey's test (α = 0.05).
  
  
  RESULTS
  Prolonged exposure times significantly increased the DC (%) (10 s [67.4 ± 17.3]; 20 s [85.9 ± 8.9] and 40 s [85.2 ± 9.0]) and decreased the NL (%) (10 s [24.8 ± 13.2]; 20 s [13.3 ± 7.5] and 40 s [13.5 ± 9.3]) for all adhesives; however it did not increase the IM μTBS for two (EO, GO) out of the three adhesives. Furthermore, this technique did not minimize dentine bond degradation.
  
  
  CONCLUSIONS
  Although longer exposure times than those recommended could not prevent degradation of dentine bonds, they could increase DC within the hybrid layer and reduced NL for all adhesives tested.
authors.affiliation: Department of Restorative Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil.
authors.forename: Viviane
authors.initials: V
authors.lastname: Hass
authors.forename: Issis
authors.initials: I
authors.lastname: Luque-Martinez
authors.forename: Nilson Biagini
authors.initials: NB
authors.lastname: Sabino
authors.forename: Alessandro D
authors.initials: AD
authors.lastname: Loguercio
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
mesh_terms: D000268:Adhesiveness; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D058105:Polymerization; D019279:Resin Cements / Q000737:chemistry; D016622:Silver Staining; D013059:Spectrum Analysis, Raman; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C505694:Clearfil S3 Bond; D017220:Dentin-Bonding Agents; C532472:Go self-etching primer; D008689:Methacrylates; D019279:Resin Cements; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; C049840:2-(dimethylamino)ethyl methacrylate; C090921:1,6-hexanediol dimethacrylate