Selective demineralisation of dentine extrafibrillar minerals—A potential method to eliminate water-wet bonding in the etch-and-rinse technique

Bingqing Li, Xiaoming Zhu, Lin Ma, Fangping Wang, Xiaoqiang Liu, Xu Yang, Jianfeng Zhou, Jianguo Tan, David Henry Pashley, Franklin Chi Meng Tay

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Objective 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. Methods Dentine surfaces were etched with different concentrations of phosphoric acid (1, 5, 10, 20, 30 or 40 wt%). 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. Results 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. Conclusions Selective demineralisation of the dentine matrix may be achieved by lowering the H3PO4 concentration to 5 wt%, to achieve better bonding performance. Clinical relevance 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.

Original languageEnglish (US)
Pages (from-to)55-62
Number of pages8
JournalJournal of Dentistry
StatePublished - Sep 1 2016


  • Collagen matrix
  • Etch-and-rinse
  • Interfibrillar space
  • Intrafibrillar mineral
  • Selective demineralisation

ASJC Scopus subject areas

  • General Dentistry


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