Interrod regions exist between the enamel rods and are known to have different crystallite orientations and a higher organic content compared to the enamel rods (the intrarod regions). This study aims to characterize the mechanical properties of both regions especially the time-dependent properties by using spherical indentation. Despite the very small amount of proteins, the interrod region shows statistically significantly higher inelastic energy dissipation than the intrarod region with increased deformation times. The total displacement under constant load (creep), viscosity, and stress relaxation behavior of both regions are also reported. Similar to the observation of previous studies, the elastic modulus and hardness in the intrarod region are significantly higher than in the interrod region.
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K.E. Healy: Dentin and enamel, in Handbook of Biomaterials Properties, edited by J. Black and G. Hastings (Chapman & Hall, London, 1995), p. 25.
P.D. Frazier: Adult human enamel: An electron microscopic study of crystallite size and morphology. J. Ultrastruct. Res. 22, 1 (1968).
G. Daculsi and B. Kerebel: High-resolution electron microscope study of human enamel crystallites: Size, shape, and growth. J. Ultrastruct. Res. 65, 163 (1978).
H. Gray, L.H. Bannister, M.M. Berry, and P.L. Williams: Gray’s Anatomy: The Anatomical Basis of Medicine & Surgery, 38th ed. (Churchill Livingstone, New York, 1995), p. 1710.
A. Nanci: Ten Cate’s Oral Histology: Development, Structure, and Function (Mosby, St Louis, 2003).
D. Bajaj and D.D. Arola: On the R-curve behavior of human tooth enamel. Biomaterials 30, 4037 (2009).
M.J. Glimcher, E.J. Daniel, D.F. Travis, and S. Kamhi: Electron optical and x-ray diffraction studies of the organization of the inorganic crystals in embryonic bovine enamel. J. Ultrastruct. Res. 50, 1 (1965).
M.C. Maas and E.R. Dumont: Built to last: The structure, function and evolution of primate dental enamel. Evol. Anthropol. 8, 133 (1999).
C.R. Carlisle, C. Coulais, and M. Guthold: The mechanical stress-strain properties of single electrospun collagen type I nanofibers. Acta Biomater. 6, 2997 (2010).
S. Habelitz, S.J. Marshall, G.W. Marshall Jr., and M. Balooch: Mechanical properties of human dental enamel on the nanometre scale. Arch. Oral Biol. 46, 173 (2001).
J. Ge, F.Z. Cui, X.M. Wang, and H.L. Feng: Property variations in the prism and the organic sheath within enamel by nanoindentation. Biomaterials 26, 3333 (2005).
M. Oyen and R.F. Cook: A practical guide for analysis of nanoindentation data. J. Mech. Behav. Biomed. Mater. 2(4), 396 (2009).
J. Mencik, L.H. He, and M.V. Swain: Determination of viscoelastic-plastic material parameters of biomaterials by instrumented indentation. J. Mech. Behav. Biomed. Mater. 2, 318 (2009).
M.L. Oyen: Spherical indentation creep following ramp loading. J. Mater. Res. 20(8), 2094 (2005).
M.L. Oyen and R.F. Cook: Load–displacement behavior during sharp indentation of viscous–elastic–plastic materials. J. Mater. Res. 18(1), 139 (2003).
S.E. Olesiak, M.L. Oyen, and V.L. Ferguson: Viscous-elastic-plastic behavior of bone using Berkovich nanoindentation. Mech. Time-Depend. Mater. 14, 111 (2010).
H.R. Hertz: Miscellaneous Papers (Macmillan, London, 1896).
J.S. Field and M.V. Swain: A simple predictive model for spherical indentation. J. Mater. Res. 8, 297 (1993).
W.C. Oliver and G.M. Pharr: An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J. Mater. Res. 7, 1564 (1992).
L.H. He and M.V. Swain: Energy absorption characterization of human enamel using nanoindentation. J. Biomat. Mater. Res. 81, 484 (2007).
E.H. Lee and J.R.M. Radok: The contact problem for viscoelastic bodies. J. Appl. Mech. 27, 438 (1960).
K.L. Johnson: Contact Mechanics (Cambridge University Press, Cambridge, 1985).
M.L. Oyen: Analytical techniques for indentation of viscoelastic materials. Philos. Mag. 86, 5625 (2006).
M. Sakai and S. Shimizu: Indentation rheometry for glass-forming materials. J. Non-Cryst. Solids 282, 236 (2001).
L.H. He and M.V. Swain: Nanoindentation creep behavior of human enamel. J. Mech. Behav. Biomed. Mater. 91, 352 (2009).
G. Williams and D.C. Watts: Non-symmetrical dielectric relaxation behavior arising from a simple empirical decay function. Trans. Faraday Soc. 66, 80 (1970).
K.L. Dorrington: The theory of viscoelasticity in biomaterials. Symp. Soc. Exp. Biol. 34, 289 (1980).
S.F. Ang, E.L. Bortel, M.V. Swain, A. Klocke, and G.A. Schneider: Size-dependent elastic/inelastic behavior of enamel over millimeter and nanometer length scales. Biomaterials 31, 1955 (2010).
S. Habelitz, G.W. Marshall, M. Balooch, and S.J. Marshall: Nanoindentation and storage of teeth. J. Biomech. 35(7), 995 (2002).
B. Viswanath, R. Raghavan, U. Ramamurty, and N. Ravishankar: Mechanical properties and anisotropy in hydroxyapatite single crystals. Scr. Mater. 57, 361 (2007).
L. Dougan, A.S. Koti, G. Genchev, H. Lu, and J.M. Fernandez: A single-molecule perspective on the role of solvent hydrogen bonds in protein folding and chemical reactions. ChemPhysChem. 9, 2836 (2008).
J. Zhang, M.M. Michalenko, E. Kuhl, and T.C. Ovaert: Characterization of indentation response and stiffness reduction of bone using a continuum damage model. J. Mech. Behav. Biomed. Mater. 3, 189 (2010).
L.H. He and M.V. Swain: Influence of environment on the mechanical behaviour of mature human enamel. Biomaterials 28, 4512 (2007).
G.A. Schneider, L.H. He, and M.V. Swain: Viscous flow model of creep in enamel. J. Appl. Phys. 103, 014701 (2008).
The authors express gratitude to German Research Foundation for financial support. We also appreciate teeth samples collection from Dr. Carmen Gottstein and Mr. Peter Stutz from University of Hamburg.
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Ang, S.F., Saadatmand, M., Swain, M.V. et al. Comparison of mechanical behaviors of enamel rod and interrod regions in enamel. Journal of Materials Research 27, 448–456 (2012). https://doi.org/10.1557/jmr.2011.409