Biomedical Engineering Reference
In-Depth Information
orthodontic forces and periodontal diseases on the mechanical properties
of cementum.
3.7.
Nanoindentation of carious lesions
Dental caries may be defined as a bacterial disease of the calcified tissues
of the teeth characterized by demineralization of the inorganic and
destruction of the organic substance of the tooth.
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Due to its long history
and wide prevalence, dental caries has attracted considerable attention of
both clinical practitioners and researchers.
From a materials science point of view, caries and pre-caries lesions
(
e.g
. white spot lesions in clinic) will have inferior mechanical properties
compared to their healthy counterparts. By considering the above
mentioned hierarchical microstructures of both enamel and dentin and
the natural procedure of acid invasion, the changes of mechanical
properties may have defining characteristics and features, which may
allow us to understand the formation and development of the lesion
such that remineralization treatments may be developed. In this field,
nanoindentation is obviously a powerful tool.
Recently, a nano-indentation characterization of artificially generated
white spot lesions (WSLs) has been reported.
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After a period of time
soaking in a mild acidic solution, sound teeth samples showed degrees of
subsurface demineralization. The partially demineralized lesion areas
have lower elastic modulus and hardness than sound areas, due to the
loss of mineral crystals. At the surface of the lesion, a less demineralized
surface zone was found.
Very recently, our group has undertaken nanoindentation
number of specific mechanical property features:
•
There is a rapid reduction in mechanical properties from sound
enamel to the WSL body;
•
The body of the lesion appears inhomogeneous with some islands that
show higher or lower elastic modulus and hardness;
•
The surface layer of the lesion showed higher elastic modulus and
hardness than the lesion body.
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