NANOINDENTATION OF BONE - Nanoindentation with Biological Applications - page 224

in mineral composition or crystallinity such as increase in crystal size,
shape, and perfection. During fossilization, a general increase in mineral
volume fraction is commonly observed along with changes in
crystallinity and composition. The process of fossilization is extremely
complex and can include loss of organic material, partial or complete
dissolution of minerals, recrystallization, collagen loss, uptake of trace
elements, and changes in porosity. 174,175 This naturally creates a wide
range of bio- and geo-mineralized, heterogeneous samples in which to
investigate variations of mineral content, composition, and crystallinity.

5. Conclusions and Future Outlook

Nanoindentation of bone and associated mineralized tissues has enabled
the mechanical study of bone at the tissue-level. Researchers have
long sought ways to evaluate bone at very small length scales,
by mechanically testing individual lamellae or a single trabecula or
through attempts to correlate non-invasive imaging or high-resolution
spectroscopic data with mechanical properties. Nanoindentation has been
demonstrated to overcome limitations of larger scale testing methods,
where researchers have previously lacked the ability to physically probe
bone material at sub-micrometer scales.
Nanoindentation serves as an ideal tool for mechanically testing bone
and bone's structural features from tens to thousands of nanometers in
depth and indent width. In combination with adjunctive techniques,
nanoindentation has and continues to prove its utility in revealing new
insight into the microstructural and compositional characteristics of bone
across types of mineralized tissues, in health and disease, in response to
altered mechanical loading, and in experimentally altered conditions.
There is also a tremendous potential for using nanoindentation to
evaluate the quality of bone that forms in or adjacent to bone
replacement materials and within small volumes of engineered bone
tissue.
Because of the potential to collect large, statistically relevant
populations of data by indenting many sites within a small region,
nanoindentation is an obvious choice for evaluation of precious samples
that may exist only in small numbers or volumes of tissue such as human