TY - JOUR
T1 - Influence of hydration on nanoindentation induced energy expenditure of dentin
AU - Bertassoni, Luiz Eduardo
AU - Swain, Michael Vincent
N1 - Funding Information:
This research was supported by the Australian Dental Research Foundation Grants nos. 46/2009 and 36/2010 and a Collin Cormie Scholarship. LEB also thanks the Australian Government for support in the form of an Endeavour International Postgraduate Award. The authors also thank Professor Michelle Oyen for insightful discussions of the effect of hydration on the indentation properties of dentin and bone.
PY - 2012/6/1
Y1 - 2012/6/1
N2 - Improved understanding of the effects of hydration and drying in mineralized tissues is highly desirable, particularly for physiologically hydrated biological materials such as dentin. We investigated the influence of hydration on the nanomechanical properties of healthy dentin and hypothesized that drying leads to an increase in indentation induced energy expenditure and hardness. Hydrated and dry dentin were tested with a UMIS set up with a Berkovich indenter at a maximum load of 50mN. Values representative of the energy expenditure behavior were presented as dissipated energy, U d, recovered energy, U e, normalized energy expenditure index, ψ, and hardness, H. Energy expenditure index results, which normalize the energy expenditure for each test and describe the relative energy dissipation-recovery behavior of a material, suggested that, for the relatively severe contact strains about a sharp Berkovich indenter, dissipation dominates the mechanical response of both the hydrated and dry dentin. In support of our initial hypothesis, dry dentin presented a significantly higher energy expenditure index than hydrated dentin (p<0.0001). These results were primarily associated with a lower U e that was found upon drying. Hydration also decreased H significantly (p<0.0001). In summary, this study presents the first direct measurements of the energy expenditure behavior of hydrated and dry dentin using instrumented nanoindentation.
AB - Improved understanding of the effects of hydration and drying in mineralized tissues is highly desirable, particularly for physiologically hydrated biological materials such as dentin. We investigated the influence of hydration on the nanomechanical properties of healthy dentin and hypothesized that drying leads to an increase in indentation induced energy expenditure and hardness. Hydrated and dry dentin were tested with a UMIS set up with a Berkovich indenter at a maximum load of 50mN. Values representative of the energy expenditure behavior were presented as dissipated energy, U d, recovered energy, U e, normalized energy expenditure index, ψ, and hardness, H. Energy expenditure index results, which normalize the energy expenditure for each test and describe the relative energy dissipation-recovery behavior of a material, suggested that, for the relatively severe contact strains about a sharp Berkovich indenter, dissipation dominates the mechanical response of both the hydrated and dry dentin. In support of our initial hypothesis, dry dentin presented a significantly higher energy expenditure index than hydrated dentin (p<0.0001). These results were primarily associated with a lower U e that was found upon drying. Hydration also decreased H significantly (p<0.0001). In summary, this study presents the first direct measurements of the energy expenditure behavior of hydrated and dry dentin using instrumented nanoindentation.
KW - Collagen
KW - Dentin
KW - Energy dissipation
KW - Energy expenditure
KW - Hardness
KW - Nanoindentation
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U2 - 10.1016/j.jbiomech.2012.03.021
DO - 10.1016/j.jbiomech.2012.03.021
M3 - Article
C2 - 22537569
AN - SCOPUS:84861188881
SN - 0021-9290
VL - 45
SP - 1679
EP - 1683
JO - Journal of Biomechanics
JF - Journal of Biomechanics
IS - 9
ER -