title: In vitro demineralisation of the cervical region of human teeth.
abstract: OBJECTIVE
  The aim of this study was to investigate a possible role for demineralisation of the cervical region of human teeth in the development of non-carious cervical lesions (NCCLs).
  
  
  METHODS
  Freshly extracted human premolars were demineralised and prepared for nanoindentation and scanning electron microscope (SEM) observation. After 1 day or 2 days demineralisation in a solution of pH 4.5, specimens were embedded, cut and polished to 1 μm diamond paste. Nanoindentation was done at the cementum-enamel junction (CEJ) region with an interval of 30 μm, to develop mechanical properties maps. After the indentation, SEM with back-scatter detector was employed to observe the degree of demineralisation at the CEJ.
  
  
  RESULTS
  After 1 day and 2 days demineralisation, the mechanical properties of enamel and dentine at the CEJ decreased by ∼50% and ∼90%, respectively. SEM images illustrate that artificial demineralisation generated typical demineralised zones in enamel near the CEJ. Moreover, 2 days demineralisation penetrated the sound enamel at the CEJ, and the dentine beneath was undermined.
  
  
  CONCLUSIONS
  One day and 2 days demineralisation reduced the mechanical properties of teeth at the CEJ significantly. Demineralised enamel and dentine with low mechanical properties are prone to wear and abrasion. The findings of the investigation indicate that acid typical of that produced by dental plaque may compromise the mechanical properties of enamel and dentine at the CEJ to the extent that they would be susceptible to tooth brush abrasion, producing NCCLs.
authors.affiliation: Sir John Walsh Research Institute, School of Dentistry, University of Otago, New Zealand. Lihong.he@otago.ac.nz
authors.forename: Li-Hong
authors.initials: LH
authors.lastname: He
authors.forename: Yingzhi
authors.initials: Y
authors.lastname: Xu
authors.forename: David G
authors.initials: DG
authors.lastname: Purton
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D001641:Bicuspid / Q000648:ultrastructure*; D002122:Calcium Chloride / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D012996:Solutions / Q000737:chemistry*; D013499:Surface Properties; D019237:Tooth Cervix / Q000648:ultrastructure*; D017001:Tooth Demineralization
chemical_list: D010710:Phosphates; D017680:Potassium Compounds; D012996:Solutions; C013216:potassium phosphate; D002122:Calcium Chloride; D019342:Acetic Acid