Biomedical Engineering Reference
In-Depth Information
MTT assay
0.400
0.300
0.200
0.100
0.000
Control
nCS
95:5
90:10
50:50 nCS:alg
FIGURE 19.11
Periodontal cell viability tests with nCS and nCS alginate scaffolds. The MTT (3-(4,5-dimethyl-thiazol-2-yl)-
2,5-diphenyl tetrazolium bromide) cell assay was conducted according to the method described previously to
measure the metabolic cell activity as an assessment of viability in the presence of the nCS-alginate scaffolds
[49]
. Control represents cells grown in tissue culture wells without added scaffolds. Viability data are
expressed as average OD
standard deviation with n
4 samples per group.
6
5
alginate scaffold developed in our laboratory has not been yet tested in
clinical studies, on the basis of the in vitro work and the in vivo animal studies, there are no appar-
ent reasons why the material should not be biocompatible and effective in supporting bone regener-
ation in the craniofacial as well as other bony sites. We are presently in the process of optimizing
conditions of the nCS
Although the nCS
1
alginate mixture so that it can be used as an injectable product with or
without growth factors in a variety of clinical conditions.
Presently, there is a different nCS product that is available for clinical use. This material is
marketed and sold as NanoGen
s
(Orthogen) and has been approved for clinical use in the United
States. Since it is a proprietary product, the exact conditions of its fabrication are not known.
However, according to Orthogen's website,
2
it has unique microscopic structure and properties.
Although the material is described as a “nanocrystalline calcium sulfate bone graft,” it is also stated
on the company's website that in the fabrication of the material microcrystalline CS is converted to
grains of CS in the range of 200
1
900 nm that are then compressed to form granulates in the sizes
ranged from 400
m, clearly not in the range of nanosized particles as they are usually
defined. Although to date there does not appear to be studies yet published documenting the claims,
the website,
2
also states that NanoGen
s
undergoes controlled degradation over a period of 12
weeks in contrast to the 4
1000
μ
6 weeks for traditional CS. Moreover, there are claims that the material
is completely replaced with regenerated vital bone, critical to its success as a bone graft. The
material is purposed to be used as a stand-alone bone graft material, in combination with other
bone graft materials or to serve as a resorbable barrier over other bone grafts in postextraction sites,
periodontal infra-osseous defects, apicoectomy, root perforations, dehiscence and fenestrations,
mini and great sinus lifting. There is a published case report in which the NanoGen
s
material has
been shown to be effective in regeneration of bone in an extraction socket of a 55-year-old female
patient with histomorphometric analysis of the bone core extracted from the regenerated socket
6 months after grafting showing 47% vital bone volume with osteoclasts and osteoblastic remodel-
ing involvement
[61]
. Although this one case does suggest that the properties of the CS product
