title: [Relationship between the microstructure and nanohardness of dentin and enamel of human teeth].
abstract: OBJECTIVE
  To investigate the relationship between the nanohardness and microstructure of the dentin and enamel of human teeth.
  
  
  METHODS
  Nano indentation was used to determine the nanohardness of enamel and dentin; TEM and IR were utilized to observe the microstructure and crystalline characteristic.
  
  
  RESULTS
  The mean nanohardness of the enamel [(4.92 +/- 0.40) GPa] was significantly higher than that of dentin [(1.17 +/- 0.14) GPa]. A large quantity of hydroxyapatite (HA) crystals and uniform lattice stripe were found in enamel but not in dentin.
  
  
  CONCLUSIONS
  The difference of nanohardness between enamel and dentin is related to their density, the inorganic morphology and phase structure.
authors.affiliation: State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Long
authors.initials: L
authors.lastname: Chen
authors.forename: Xi-ping
authors.initials: XP
authors.lastname: Song
authors.forename: Bei
authors.initials: B
authors.lastname: Zhang
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.forename: Yu-xing
authors.initials: YX
authors.lastname: Bai
mesh_terms: D000328:Adult; D003743:Dental Enamel / Q000502:physiology* / Q000648:ultrastructure*; D003804:Dentin / Q000502:physiology* / Q000648:ultrastructure*; D006244:Hardness; D006801:Humans; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures