title: Hydromechanics in dentine: role of dentinal tubules and hydrostatic pressure on mechanical stress-strain distribution.
abstract: OBJECTIVE
  This investigation is to understand the role of free water in the dentinal tubules on the mechanical integrity of bulk dentine.
  
  
  METHODS
  Three different experiments were conducted in this study. In experiment 1, three-dimensional models of dentine with gradient elastic modulus, homogenous elastic modulus, and with and without hydrostatic pressure were simulated using the finite element method. Static compressive loads of 15, 50 and 100 N were applied and the distribution of the principal stresses, von Mises stresses, and strains in loading direction were determined. In experiment 2, experimental compression testing of fully hydrated and partially dehydrated dentine (21 degrees C for 72 h) was conducted using a Universal testing machine. In experiment 3, Fourier transform infrared spectroscopic analysis of hydrated and partially dehydrated dentine was carried out.
  
  
  RESULTS
  The finite element analysis revealed that the dentine model with simulated hydrostatic pressure displayed residual tensile stresses and strains in the inner region adjacent to the root canal. When external compressive loads were applied to the model, the residual stresses and strains counteracted the applied loads. Similarly the hydrated specimens subjected to experimental compression loads showed greater toughness when compared to the partially dehydrated specimens. The stress at fracture was significantly higher in partially dehydrated specimens (p=0.014), while the strain at fracture was significantly higher in hydrated dentine specimens (p=0.037).
  
  
  CONCLUSIONS
  These experiments highlighted the distinct role of free water in the dentinal tubules and hydrostatic pressure on the stress-strain distribution within the bulk dentine.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074, Republic of Singapore. rsdak@nus.edu.sg
authors.forename: A
authors.initials: A
authors.lastname: Kishen
authors.forename: S
authors.initials: S
authors.lastname: Vedantam
mesh_terms: D001696:Biomechanical Phenomena; D003799:Dental Stress Analysis / Q000379:methods*; D003804:Dentin / Q000737:chemistry / Q000648:ultrastructure*; D020342:Finite Element Analysis; D006874:Hydrostatic Pressure; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water
chemical_list: D014867:Water