Biomedical Engineering Reference
In-Depth Information
Cells are sufficiently sensitive and nano-scale alterations in
topography might elicit diverse cell behavior [586-588]. How cells
can recognize the particle size and other very small differences in the
properties of nano-sized HA in these experiments remains unclear.
Actually, determining the mechanisms whereby nano-sized particles
of calcium orthophosphates and their sizes exert effects on bone-
related cells will require further systematic studies.
3.7.3
Dental Applications
Dental caries is a ubiquitous and worldwide oral disease. At the
initial stage of caries lesions, bacteria cause damage of dental enamel,
which is the exterior coating of teeth and possesses remarkable
hardness and resistance. As the most highly mineralized structure
in vertebrate bodies, enamel is composed of numerous needle-
like apatite crystals of nanodimensional sizes, which are bundled
in parallel ordered prisms to ensure unique mechanical strength
and biological protection (see section 1.4.2 of this topic). As a non-
living tissue, the main constituent (~97 wt. %) of mature enamel
is inorganic nanodimensional apatite so that enamel is scarcely
self-repaired by living organisms after substantial mineral loss.
Filling with artificial materials is a conventional treatment to repair
damaged enamel. However, secondary caries frequently arise at the
interfaces between the tooth and foreign materials [589].
Nanodimensional HA and CDHA are often considered as model
compounds of dental enamel due to the chemical and phase
similarities [123, 174, 175]. Therefore, enamel remineralization by
using nanodimensional apatite or other calcium orthophosphates is
suggested in dental research. For example, toothpastes containing
nanodimentional apatite could promote a partial remineralization of
demineralized enamel [590-592], as well as possess some whitening
effect [593]. Furthermore, nano-sized HA might be added to a
fluoride-containing mouthrinse [594]. A remineralization potential
of sports drink, containing nano-sized HA, was also investigated
[595]. A positive influence of addition of nanodimensional β-TCP
against acid demineralization and promoted remineralization of
enamel surface was detected as well [596]. Unfortunately, these
chemically analogous compounds of enamel are not widely applied
in clinical practices. The native structure of dental enamel is too
complex to be remodeled and the synthesized apatite crystallites
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