Biomedical Engineering Reference
In-Depth Information
Presently, there are only a few studies of nanotechnology as to what has been demonstrated at a
larger scale. Smith et al.
[96]
examined the development of nanostructured polymer scaffolds for
regeneration and bioengineering. The study focused on nanofibrous (NF) scaffolds with the incor-
poration of other components. Since extracellular matrices (ECM) are composed of collagen fibers
between 50 and 500 nm, a biodegradable polymer was cast into a porous scaffold resulting in a NF
pore-wall structure with nanofibers of the same diameter as found in ECM. In both NF and com-
posite control scaffolds, cell adhesion, proliferation, and differentiation improved. The creation of a
synthetic replica of the naturally occurring ECM has the potential to promote new tissue formation
and is a huge step in understanding the enhanced biological regulation of cell behavior for tissue
repair and regeneration
[96]
.
The behavior of dental pulp stem cells on NF/gelatin/nano-hydroxyapatite NHA scaffolds was
investigated. Dental pulp stem cells (DPSCs) were seeded on electrospun poly(epsilon caprolac-
tone)/gelatin scaffolds with or without nanohydroxyapatite (NHA). Various tests (in vitro DNA
content, ALP activity, and osteocalcin measurements) showed that the scaffolds supported DPSC
adhesion, proliferation, and odontoblast differentiation. The presence of NHA upregulated ALP
activity and promoted OC expression. Both scaffolds seeded with DPSCs were subcutaneously
implanted into immunocompromised nude mice. Controls consisted of scaffolds with NHA but not
seeded with DPSCs. Results showed that the combination of NHA on scaffolds upregulated expres-
sion of specific odontogenic genes and NHAs on nanofibers enhanced DPSC differentiation toward
and odontoblast-like phenotype (-like cell) both in vitro and in vivo
[97]
. Wang et al.
[98]
exam-
ined the odontogenic differentiation of human DPSCs on NF poly(
L
-lactic acid) PLLA scaffolds.
Highly porous NF-PLLA scaffolds mimicking collagen, type-I fibers were fabricated and seeded
with DPSCs with and without Bone Morphogenic Protein-7 (BMP-7) growth factors and DXM
-Dexamethasone(DXM) medium containing an assortment of other molecules. The combination of
BMP-7 and DXM induced odontogenic differentiation more effectively than DXM alone. The
nanoscaffolds provide an excellent environment for DPSCs to regenerate dental pulp and dentin. In
a recent review, Gupta and Ma
[99]
used a multiscale scaffold incorporating nanofibrous features
to mimic ECM with a porous network for regeneration of tissues. Results showed that creation of a
microenvironment using nanofibrous scaffolds led to the formation of cartilage, enamel, dentin, and
periodontal ligament regeneration. The authors state, however, that more studies are needed to
understand the mechanisms of the nanofiber effects. There remains a significant technical challenge
for the synthetic integration of structural mechanisms with biologic mechanisms to achieve func-
tional tissue regeneration.
21.6
Conclusion
As may be seen by the above text, the full impact of nanotechnology in endodontics is still not real-
ized. There seems to be nanoapplication for all aspects of routine root canal procedures. Whether it
is the instruments and irrigants that are used to clean and shape root canals, or materials used to
seal the cleaned root canal system, nanomaterials show potential to further improve their physical
and chemical characteristics. In addition to these physical and chemical improvements, perhaps a
major outcome of nanoenhancement would be the development of “smart” materials. “Smart” by
