title: Defying ageing: An expectation for dentine bonding with universal adhesives?
abstract: OBJECTIVE
  The present study evaluated the long-term dentine bonding effectiveness of five universal adhesives in etch-and-rinse or self-etch mode after 12 months of water-ageing.
  
  
  METHODS
  The adhesives evaluated included All-Bond Universal, Clearfil Universal Bond, Futurabond U Prime&Bond Elect and Scotchbond Universal. Microtensile bond strength and transmission electron microscopy of the resin-dentine interfaces created in human coronal dentine were examined after 24h or 12 months.
  
  
  RESULTS
  Microtensile bond strength were significantly affected by bonding strategy (etch-and-rinse vs self-etch) and ageing (24h vs 12 months). All subgroups showed significantly decreased bond strength after ageing except for Prime&Bond Elect and Scotchbond Universal used in self-etch mode. All five adhesives employed in etch-and-rinse mode exhibited ultrastructural features characteristic of collagen degradation and resin hydrolysis. A previously-unobserved inside-out collagen degradation pattern was identified in hybrid layers created by 10-MDP containing adhesives (All-Bond Universal, Scotchbond Universal and Clearfil Universal Bond) in the etch-and-rinse mode, producing partially degraded collagen fibrils with intact periphery and a hollow core. In the self-etch mode, all adhesives except for Prime&Bond Elect exhibited degradation of the collagen fibrils along the thin hybrid layers. The three 10-MDP containing universal adhesives did not protect surface collagen fibrils from degradation when bonding was performed in the self-etch mode.
  
  
  CONCLUSIONS
  Despite the adjunctive conclusion that bonds created by universal adhesives in the self-etch bonding mode are more resistant to decline in bond strength when compared with those bonds created using the etch-and-rinse mode, bonds created by universal adhesives are generally incapable of defying ageing.
authors.affiliation: Department of Prosthodontics, School & Hospital of Stomatology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Zheng-yi
authors.initials: ZY
authors.lastname: Zhang
authors.affiliation: Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, China.
authors.forename: Fu-cong
authors.initials: FC
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, Shaanxi, China. Electronic address: niulina831013@126.com.
authors.forename: Li-na
authors.initials: LN
authors.lastname: Niu
authors.affiliation: The Dental College of Georgia, Augusta University, Augusta, GA, USA.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Ochala
authors.affiliation: Department of Operative Dentistry & Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Prosthodontics, School & Hospital of Stomatology, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Bai-ping
authors.initials: BP
authors.lastname: Fu
authors.affiliation: Department of Cariology and Endodontology, School and Hospital of Stomatology, Peking University, Beijing, China.
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Wang
authors.affiliation: The Dental College of Georgia, Augusta University, Augusta, GA, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Pashley
authors.affiliation: The Dental College of Georgia, Augusta University, Augusta, GA, USA. Electronic address: ftay@gru.edu.
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003094:Collagen / Q000378:metabolism; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D003743:Dental Enamel / Q000648:ultrastructure*; D003804:Dentin / Q000000981:diagnostic imaging / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry* / Q000145:classification; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C103500:Prime & Bond; D019279:Resin Cements; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; D003094:Collagen; C041330:Scotchbond