Biomedical Engineering Reference
In-Depth Information
FIGURE 20.3
The organization of dental enamel. Scanning electron micrograph of the surface of an acid-etched ground
section of mature mouse incisal dental enamel. Ordered arrays of enamel prisms are each constructed of
parallel bundles of carbonated HA enamel crystallites.
Adapted from Ref.
[47]
. Reprinted with permission from Elsevier.
However, enamel cannot heal itself by a cellular repair as enamel is both acellular and avascu-
lar. It loses mineral substances due to caries, trauma, and erosion. Restorations of damaged tooth
tissues with artificial materials represent the traditional therapeutic solutions. Although many
sophisticated materials are now available for restoration, their use is not yet completely satisfactory.
A combination of tissue bioengineering with the development of genetically designed trigger nano-
particles which are biomimetic with mineralized tissues, have begun to bear fruit in the manufactur-
ing of in vitro teeth tissue even the whole teeth. For example the amelogenin gene has been
manipulated to adhere to HA nanoparticles. When these are directly shot to pluripotential cells
encapsulated in nanohydrogels they begin to work on the formation of the enamel tissue
[48]
.The
previous attempts to engineer enamel focused mainly on chemical synthesis. Chen et al.
[49]
syn-
thesized and modified the HA nanorod surface with monolayers of surfactants to create specific
surface characteristics that allowed the nanorods to self-assemble into an enamel prism-like struc-
ture at a water/air interface. The size of the synthetic HA nanorods can be controlled, and synthe-
sized nanorods were similar in size to both human and rat enamel crystals. In other studies, prism-
like structures, consisting of fluoroapatite crystals similar to the dimensions of those seen in human
enamel have been synthesized using hydrothermal method
[50]
. This method is a widely adopted
nanotechnology to create nanorods, nanowires, and whiskers and has already been shown to be an
effective way to create different kinds of nanomaterials
[51
53]
. However, the majority of these
synthesis methods were developed using high temperature, high pressure, and extremely acidic pH
or in the presence of a concentrated solution of surfactants. It is generally accepted that the biomi-
metic synthesis of enamel-like apatite structures under physiological condition is an alternative
restorative pathway. Recently, Li et al.
[54]
reported that a bioinspired cooperative effect of
an amino acid (glutamic acid, Glu) and nano-apatite particles can result in the regeneration of
