Osteoblast Behavior on Nanostructured Implant Materials - Bionanomaterials for Dental Applications - page 373

Table 12.6 Quantiications of metallic elements in the extracts

Sample

Element 316L [mg/L] Fe 74 Cr 24 Mo 2 N [mg/L] Fe 54 Cr 24 Mn 21 Mo 1 N [mg/L]

4.6 ± 0.6 4.2 ± 0.5 4.3 ± 0.5

Fe 0.00 0.00 0.00

Mn 0.00 — 0.00

Mo 0.00 0.00 0.00

Ni 0.21 ± 0.03 0.10 ± 0.02 0.10 ± 0.02

The quantiication of the metallic elements in each extract of
the samples was undertaken for Cr, Fe, Mn, Mo and, Ni under the
optimum condition for each element and the results are shown in
Table 12.6.
In the extract of 316L, Ni was detected at a concentration of
0.21 ± 0.03 mg/L. Under dynamic conditions in the cell culture
medium, the presence Ni was also observed with Fe 74 Cr 24 Mo 2 N and
Fe 54 Cr 24 Mn 21 Mo 1 N, although nickel is not present as a constituent
element. It should be noted that the presence of Ni was also reported
from Ti-6Al-4V as an impurity at a concentration less than 0.01
mass% [150]. Iron and chromium oxides are the main component of
the surface oxide on 316L and Fe 74 Cr 24 Mo 2 N and Fe 54 Cr 24 Mn 21 Mo 1 N,
but small amounts of nickel, molybdenum, and manganese oxides
were also detected in the surface oxide layer. However, the stability
of nickel oxide is relatively low compared to chromium and other
oxides, thus the preferential release of nickel could occur.
Additionally, in all extracts of 316L, Fe 74 Cr 24 Mo 2 N, and
Fe 54 Cr 24 Mn 21 Mo 1 N chromium was detected at the concentration
of 4.6 ± 0.6, 4.2 ± 0.5, and 4.3±0.5 mg/L, respectively. Chromium is
one of the essential elements for humans, so a small amount of this
element may contribute to cell proliferation, resulting in higher cell
growth [148].
These results indicate that Fe 74 Cr 24 Mo 2 N and Fe 54 Cr 24 Mn 21 Mo 1 N
have superior cytocompatibility than the conventional metallic
biomaterial, 316L. Additionally, the nitrogen adsorption
treatment increases the corrosion resistance of Fe 74 Cr 24 Mo 2 N
and Fe 54 Cr 24 Mn 21 Mo 1 N. The addition of nitrogen to stainless
steel inluences the corrosion resistance of the steel. Recently,
microcrystalline Ni-free stainless steel was manufactured by the