title: Time dependent deformation behavior of dentin.
abstract: OBJECTIVE
  The viscoelastic behavior of dentin and its ability to undergo time dependent deformation are considered to be important to oral functions and its capacity to resist fracture. There are spatial variations in the microstructure of dentin within the crown, which could be important to the viscous behavior. However, a spatially resolved description for the viscoelastic behavior of coronal dentin has not been reported.
  
  
  METHODS
  In this investigation spherical indentations were made in three regions of coronal dentin including the outer, middle and inner regions. Power law relations were developed to quantitatively describe the stress-strain responses of the tissue.
  
  
  RESULTS
  Results showed that the deformation behavior was strongly dependent on the composition (mineral to collagen ratio) and microstructure (tubule density), which contributed to an increase in the rate of viscous deformation with increasing proximity to the pulp.
  
  
  CONCLUSIONS
  A model accounting for spatial variations in composition and microstructure was developed to describe the steady-state time dependent deformation behavior of coronal dentin, and a good agreement was found with the experimental results.
authors.affiliation: School of Engineering, Universidad Eafit, Medellín, Colombia.
authors.forename: C
authors.initials: C
authors.lastname: Montoya
authors.affiliation: Department of Materials Science & Engineering, University of Washington, Seattle, WA, USA; Departments of Restorative Dentistry and Oral Health Sciences, School of Dentistry, University of Washington, Seattle, WA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Arola
authors.affiliation: School of Engineering, Universidad Eafit, Medellín, Colombia. Electronic address: eossa@eafit.edu.co.
authors.forename: E A
authors.initials: EA
authors.lastname: Ossa
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003804:Dentin / Q000737:chemistry* / Q000648:ultrastructure*; D005260:Female; D006244:Hardness; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008964:Molar, Third; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014783:Viscosity
keywords: Creep; Dentin; Lumen area fraction; Mineral-to-collagen ratio; Spherical indentation