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Mechanical strength and biocompatibility of ultrafine-grained commercial purity titanium.

Estrin Y, Kim HE, Lapovok R, Ng HP, Jo JH - Biomed Res Int (2013)

Bottom Line: The effect of grain refinement of commercial purity titanium by equal channel angular pressing (ECAP) on its mechanical performance and bone tissue regeneration is reported.However, the observed combination of outstanding mechanical properties achieved by ECAP without a loss of biocompatibility suggests that this is a very promising processing route to bioimplant manufacturing.The study thus supports the expectation that commercial purity titanium modified by ECAP can be seen as an excellent candidate material for bone implants suitable for replacing conventional titanium alloy implants.

View Article: PubMed Central - PubMed

Affiliation: Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, VIC 3800, Australia. yuri.estrin@monash.edu

ABSTRACT
The effect of grain refinement of commercial purity titanium by equal channel angular pressing (ECAP) on its mechanical performance and bone tissue regeneration is reported. In vivo studies conducted on New Zealand white rabbits did not show an enhancement of biocompatibility of ECAP-modified titanium found earlier by in vitro testing. However, the observed combination of outstanding mechanical properties achieved by ECAP without a loss of biocompatibility suggests that this is a very promising processing route to bioimplant manufacturing. The study thus supports the expectation that commercial purity titanium modified by ECAP can be seen as an excellent candidate material for bone implants suitable for replacing conventional titanium alloy implants.

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Titanium screws implanted in the rabbit tibia. (Right: CT scan.)
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fig4: Titanium screws implanted in the rabbit tibia. (Right: CT scan.)

Mentions: Four New Zealand white rabbits were used as test objects. Screws made from the as-received and the ECAP-modified titanium were CNC machined and implanted in the tibia of the hind legs of a rabbit after ultrasonic cleaning in a distilled water bath for 1 h and sterilisation by γ-radiation. Figure 3 shows the surface morphologies of the screws imaged by a JEM-7001F FEG scanning electron microscope (SEM) operated at 5 kV. The machined surfaces of the as-received and ECAP-modified screws were characterised by a dense array of circumferential grooves, each having a width in the range of 80–110 nm. High resolution edge-on images of the screw surface profile further revealed that these nanoscale grooves typically had a peak-to-peak distance of the order of tens of nanometres. No significant difference could be identified between the two types of screws in terms of the extent of roughness in the micron-to-submicron range, that is, the microroughness. The animals were anesthetised with a combination of 1.5 cc of 2% xylazine HCl (Rompun, Bayer Korea) and 0.5 cc of tiletamine HCl (Zoletil, Virbac Laboratories, France) and lidocaine (Yuhan Corporation, Republic of Korea). Additionally, 1 : 100,000 epinephrine was injected for the local anesthesia. Two defects were made on each tibia using a 3 mm diameter trephine drill. The screw samples were implanted into the tibial bone defects. After the surgery, the wounds were sutured with Surgisorb (Samyang Ltd., Republic of Korea), and then cephradine (Bayer Korea), an antibiotic, was injected into the rabbit for 3 days. Only the screws implanted in the lower (distal) portion of the tibia, where the cortical bone thickness was sufficiently uniform, were used in the present test. (The screws implanted in the upper (proximal) parts of the tibia were not suitable, as the cortical bone thickness is not sufficiently uniform there. These were used for separate tests not reported here.) Hence, a total of four screws of each kind were investigated (Figure 4). While this cannot be considered as a statistically large sample, the animal ethics considerations had priority, and only four animals were sacrificed for the test. They were euthanised four weeks after surgery. The test was carried out in compliance with the strict animal ethics regulations of the Seoul National University.


Mechanical strength and biocompatibility of ultrafine-grained commercial purity titanium.

Estrin Y, Kim HE, Lapovok R, Ng HP, Jo JH - Biomed Res Int (2013)

Titanium screws implanted in the rabbit tibia. (Right: CT scan.)
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3713372&req=5

fig4: Titanium screws implanted in the rabbit tibia. (Right: CT scan.)
Mentions: Four New Zealand white rabbits were used as test objects. Screws made from the as-received and the ECAP-modified titanium were CNC machined and implanted in the tibia of the hind legs of a rabbit after ultrasonic cleaning in a distilled water bath for 1 h and sterilisation by γ-radiation. Figure 3 shows the surface morphologies of the screws imaged by a JEM-7001F FEG scanning electron microscope (SEM) operated at 5 kV. The machined surfaces of the as-received and ECAP-modified screws were characterised by a dense array of circumferential grooves, each having a width in the range of 80–110 nm. High resolution edge-on images of the screw surface profile further revealed that these nanoscale grooves typically had a peak-to-peak distance of the order of tens of nanometres. No significant difference could be identified between the two types of screws in terms of the extent of roughness in the micron-to-submicron range, that is, the microroughness. The animals were anesthetised with a combination of 1.5 cc of 2% xylazine HCl (Rompun, Bayer Korea) and 0.5 cc of tiletamine HCl (Zoletil, Virbac Laboratories, France) and lidocaine (Yuhan Corporation, Republic of Korea). Additionally, 1 : 100,000 epinephrine was injected for the local anesthesia. Two defects were made on each tibia using a 3 mm diameter trephine drill. The screw samples were implanted into the tibial bone defects. After the surgery, the wounds were sutured with Surgisorb (Samyang Ltd., Republic of Korea), and then cephradine (Bayer Korea), an antibiotic, was injected into the rabbit for 3 days. Only the screws implanted in the lower (distal) portion of the tibia, where the cortical bone thickness was sufficiently uniform, were used in the present test. (The screws implanted in the upper (proximal) parts of the tibia were not suitable, as the cortical bone thickness is not sufficiently uniform there. These were used for separate tests not reported here.) Hence, a total of four screws of each kind were investigated (Figure 4). While this cannot be considered as a statistically large sample, the animal ethics considerations had priority, and only four animals were sacrificed for the test. They were euthanised four weeks after surgery. The test was carried out in compliance with the strict animal ethics regulations of the Seoul National University.

Bottom Line: The effect of grain refinement of commercial purity titanium by equal channel angular pressing (ECAP) on its mechanical performance and bone tissue regeneration is reported.However, the observed combination of outstanding mechanical properties achieved by ECAP without a loss of biocompatibility suggests that this is a very promising processing route to bioimplant manufacturing.The study thus supports the expectation that commercial purity titanium modified by ECAP can be seen as an excellent candidate material for bone implants suitable for replacing conventional titanium alloy implants.

View Article: PubMed Central - PubMed

Affiliation: Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, VIC 3800, Australia. yuri.estrin@monash.edu

ABSTRACT
The effect of grain refinement of commercial purity titanium by equal channel angular pressing (ECAP) on its mechanical performance and bone tissue regeneration is reported. In vivo studies conducted on New Zealand white rabbits did not show an enhancement of biocompatibility of ECAP-modified titanium found earlier by in vitro testing. However, the observed combination of outstanding mechanical properties achieved by ECAP without a loss of biocompatibility suggests that this is a very promising processing route to bioimplant manufacturing. The study thus supports the expectation that commercial purity titanium modified by ECAP can be seen as an excellent candidate material for bone implants suitable for replacing conventional titanium alloy implants.

Show MeSH