title: Selective demineralisation of dentine extrafibrillar minerals-A potential method to eliminate water-wet bonding in the etch-and-rinse technique.
abstract: The present study tested the central hypothesis that selective demineralisation of dentine extrafibrillar minerals by lowering the phosphoric acid concentration improves the quality of the resin-dentine interface.
  
  
  
  Dentine surfaces were etched with different concentrations of phosphoric acid (1, 5, 10, 20, 30 or 40wt%). Scanning electron microscopy was used to observe the micromorphology of the etched dentine surfaces. Energy dispersive X-ray analysis was performed to determine the residual Ca-content of the demineralised dentine matrix. Atomic force microscopy-based nanoindentation was used to analyse the nanomechanical properties of the treated dentine surfaces. The influence of H3PO4 concentration on resin-dentine bond strength was evaluated by microtensile bond strength testing. One-way ANOVA was used to compare the residual Ca-content ratio, reduced elastic modulus (Er) of the treated dentine surfaces and microtensile bond strength among groups.
  
  
  
  Collagen fibrils appeared to be wider in diameter after etching with 5% and 10% H3PO4. The partially-demineralized collagen scaffold retained part of its rigidity to maintain an uncollapsed three-dimensional structure. Etching with 1% H3PO4 resulted in the highest residual Ca-content ratio and Er of demineralised dentine matrix, followed by 5% H3PO4. Those values were all significantly higher than values derived from the other groups. Etching with 30% H3PO4 resulted in the lowest Ca-content ratio and Er. Using 5% H3PO4 as etchant resulted in the highest resin-dentine bond strength.
  
  
  
  Selective demineralisation of the dentine matrix may be achieved by lowering the H3PO4 concentration to 5wt%, to achieve better bonding performance.
  
  
  
  By retaining intrafibrillar minerals, more through air-drying of the partially demineralised collagen matrix may be accomplished without the need to worry about collapsing a mineral-free collagen matrix during air-drying. This may result in the elimination of water-wet bonding during the application of etch-and-rinse adhesives.
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China.
authors.forename: Bingqing
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Stomatology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.affiliation: Department of Prosthodontics, Qingdao Stomatological Hospital, Qingdao, Shandong, PR China.
authors.forename: Fangping
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China.
authors.forename: Xu
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China. Electronic address: dentistzjf@163.com.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Prosthodontics, Peking University School and Hospital of Stomatology, Beijing, PR China. Electronic address: tanwume@vip.sina.com.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Tan
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@augusta.edu.
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
mesh_terms: D015519:Bone Density; D001840:Dental Bonding; D003804:Dentin; D017220:Dentin-Bonding Agents; D008855:Microscopy, Electron, Scanning; D019279:Resin Cements; D013718:Tensile Strength; D014867:Water
chemical_list: D017220:Dentin-Bonding Agents; D019279:Resin Cements; D014867:Water
keywords: Collagen matrix; Etch-and-rinse; Interfibrillar space; Intrafibrillar mineral; Selective demineralisation