Al-Murshedi, Hanan Ali Hameed
(2018)
Antibacterial, biocompatibility and nanomechanical properties of TI-6AL-7NB alloy coated with copper, hydroxyapatite and copper ion doped hydroxyapatite for dental implants.
Masters thesis, Universiti Sains Malaysia.
Abstract
Implant-associated infection has been a serious clinical problem. An effective
absence of surgical associated infection is one of the keys for a successful oral
implant therapy. The aims of this study were to evaluate the antibacterial,
cytotoxicity, cell attachment and nanoindentation of titanium-6 aluminium-7 niobium
(Ti-6Al-7Nb) alloy coated with synthesized copper, hydroxyapatite and copper ion
doped hydroxyapatite. The antibacterial performance of coated and uncoated samples
on Staphylococcus aureus and Staphylococcus epidermidis was performed using two
types of agar (Mannitol Salt Agar (MSA) and Mueller Hinton Agar (MHA)) that was
evaluated after day 1, 2 and 3 by disk diffusion test. In addition, antibacterial
properties of coated and uncoated samples on Porphyromonas gingivalis, S. aureus
and S. epidermidis were compared after day 1, 2 and 3 by disk diffusion and broth
culture tests. Statistical analysis was performed using repeated-ANOVA (P< 0.05).
The effect of cell toxicity and function of coated and uncoated samples were assessed
using methyl-thiazol-diphenyltetrazolium (MTT) assay on human fetal osteoblast
(hFOB) cells after 24 and 72 hours. One-way analysis of variance (ANOVA)
followed by post-hoc multiple comparisons analysis using Scheffe test were used.
The cell morphology and attachment were evaluated after 24 and 72 hours using
inverted microscope and observed under SEM respectively. Furthermore, the effectsof nCu addition on hardness and elastic modulus of coated layer was investigated by
nanoindentation. Statistical analysis was completed using Kruskal-Wallis test (P<
0.05). The results showed that the antibacterial evaluation using agar diffusion and
broth culture tests indicated that Ti Cu and Ti Cu/HA significantly inhibit the growth
of S. aureus, S. epidermidis and P. gingivalis while Ti and Ti HA demonstrated no
antibacterial effect. Additionally, MSA yielded comparable result to MHA when
used as the medium for testing bacterial susceptibility using agar diffusion test. The
MTT assay showed that Cu content on the surface of Ti-6Al-7Nb alloys has no
cytotoxic effect on cell viability. The cell viability rate for Ti Cu/HA was kept at
significantly higher value on day 3 as compared to day 1, indicating that hFOB cells
grow at a high proliferation rate. Microscopic evaluation indicated no differences in
the cell morphology among all samples. Under SEM, the cell attachment properties
for all samples were favourable. Nevertheless, hFOB cells attached and formed more
bridges on Ti HA and Ti Cu/HA compared to Ti and Ti Cu groups. The
nanoindentation results confirmed that the hardness and elastic modulus of HA were
significantly improved by incorporating nCu. In conclusion, the results suggest that
the surface modification of Ti-6Al-7Nb alloy with nCu/HA may be good for local
control of infection for dental implant with no adverse effect on the cytotoxicity of
hFOB cells. Also, the addition of nCu may be recommended to improve the
nanomechanical properties of the coating layer to Ti-6Al-7Nb alloy.
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