title: Effect of thermal stresses on the mechanism of tooth pain.
abstract: BACKGROUND
  Daily hot and cold thermal loadings on teeth may result in structural deformation, mechanical stress, and pain signaling. The aim of this study was to compare the adverse effects of hot and cold beverages on an intact tooth and, then, to provide physical evidence to support the hydrodynamic theory of tooth pain sensation mechanism.
  
  
  METHODS
  Three-dimensional finite element analysis was performed on a premolar model subjected to hot and cold thermal loadings. Elapsed times for heat diffusion and stress detection at the pulp-dentin junction were calculated as measures of the pain sensation.
  
  
  RESULTS
  Extreme tensile stress within the enamel resulted in damage in cold loadings. Also, extreme values of stress at the pulpal wall occurred 21.6 seconds earlier than extreme temperatures in hot and cold loadings.
  
  
  CONCLUSIONS
  The intact tooth was remarkably vulnerable to cold loading. Earlier changes in mechanical stress rather than temperature at the pulp-dentin junction indicate that the dental pain caused by hot or cold beverages may be based on the hydrodynamic theory.
authors.affiliation: Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran.
authors.forename: Iman Z
authors.initials: IZ
authors.lastname: Oskui
authors.affiliation: Faculty of Biomedical Engineering, Hamedan University of Technology, Hamedan.
authors.forename: Mohammed N
authors.initials: MN
authors.lastname: Ashtiani
authors.affiliation: Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran. Electronic address: a.hashemi@aut.ac.ir.
authors.forename: Ata
authors.initials: A
authors.lastname: Hashemi
authors.affiliation: Dental Research Center, Department of Endodontics, Faculty of Dentistry Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Jafarzadeh
mesh_terms: D001641:Bicuspid / Q000502:physiology; D001696:Biomechanical Phenomena; D003080:Cold Temperature; D003743:Dental Enamel / Q000502:physiology; D003782:Dental Pulp / Q000502:physiology; D003804:Dentin / Q000502:physiology; D004058:Diffusion; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006358:Hot Temperature; D006801:Humans; D057446:Hydrodynamics; D021621:Imaging, Three-Dimensional / Q000379:methods; D013314:Stress, Mechanical; D013816:Thermodynamics; D014098:Toothache / Q000503:physiopathology*
keywords: Finite element; mechanical stress; pain sensation; thermal load; tooth