Improvement of Apatite-Forming Ability of Titanium Metal Enriched with Calcium Ion on its Surface

It has been shown that titanium metal subjected to NaOH and heat treatments spontaneously forms a bonelike apatite on its surface in the living body and bonds to living bone. However, its apatite-forming ability was liable to decrease when the treated titanium metal was stored in humid environment. In the present study, the NaOH-treated titanium metal was soaked in a CaCl2 solution at 40°C for 24h, heat-treated at 600°C for 1h, and then soaked in ultrapure water at 80°C for 24h. Calcium titanate was formed on the surface of the titanium metal 1µm in thickness by these treatments. The resultant titanium metal showed high scratch resistance and high apatite-forming ability in a simulated body fluid. This high apatite-forming ability was maintained even after the titanium metal was kept in 95% relative humidity at 80°C for 1 week.

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Mechanism of Apatite Formation on Bioactive Titanium Metal

MRS Proceedings ◽

10.1557/proc-599-129 ◽

1999 ◽

Vol 599 ◽

Cited By ~ 2

Author(s):

T. Kokubo ◽

H.-M. Kim ◽

H. Takadama ◽

M. Uchida ◽

S. Nishiguchi ◽

...

Keyword(s):

Sol Gel ◽

Sodium Titanate ◽

Amorphous Structure ◽

Apatite Layer ◽

Apatite Formation ◽

Titanium Metal ◽

Oh Groups ◽

Living Body ◽

Heat Treated ◽

Bonelike Apatite

AbstractThe present authors previously showed that titanium metal, which was exposed to 5.OMNaOH solution at 60°C for 24 h and heat-treated at 600°C for 1 h, spontaneously forms a bonelike apatite layer on its surface in the living body, and tightly bonds to the bone through the apatite layer. In the present study, mechanism of the apatite formation on the bioactive titanium metal was investigated in an acellular simulated body fluid (SBF). A thin sodium titanate layer was formed on the surface of the titanium metal by the NaOH and heat treatments. The sodium titanate layer released Na+ ions via exchange with H3O+ ions in SBF, to form a lot of Ti-OH groups on its surface. The Ti-OH groups first combined with Ca2+ ions in SBF, and then later with PO43- ions to form the apatite. Titania and Na2O-TiO2 gels prepared by a sol-gel method as model substances of the sodium titanate layer on the surface of the titanium metal showed that Ti-OH groups of anatase structure are effective for the apatite nucleation, whereas those of amorphous structure and Na2Ti5O11 crystal are not effective.

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Bioactive Ti Metal with Ca-Enriched Surface Layer Able to Release Sr Ions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.587.269 ◽

2013 ◽

Vol 587 ◽

pp. 269-274 ◽

Cited By ~ 1

Author(s):

Seiji Yamaguchi ◽

Shekhar Nath ◽

Tomiharu Matsushita ◽

Tadashi Kokubo

Keyword(s):

Calcium Titanate ◽

Apatite Formation ◽

Mixed Solution ◽

Living Body ◽

Sodium Hydrogen ◽

Heat Treated ◽

Living Bone ◽

Naoh Solution ◽

Na Ions ◽

Phosphate Buffered Saline

Bioactive Ti metal able to release Sr ions was prepared by chemical and heat treatments of Ti metal. Ti metal was initially soaked in 5M NaOH solution to form sodium hydrogen titanate. It was soaked in a mixed solution of CaCl2 and SrCl2 to replace its Na ions with Ca and Sr ions at a given range from 0.18 to 1.62 in Sr/Ca ratio. When it was heat-treated at 600 oC, it formed Sr-containing calcium titanate (SrCT) and rutile. The apatite formation in SBF of the treated metal was low, but increased markedly by subsequently soaking the metal in 1 M SrCl2 solution at 80 oC. Thus, the treated metal gradually released Sr ions into phosphate-buffered saline up to 0.9 ppm. It is expected that the Ti metal formed with the bioactive SrCT layer could release Sr ions in a living body to promote bone formation, and bond to a living bone through an apatite.

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Apatite-forming ability of titanium in terms of pH of the exposed solution

Journal of The Royal Society Interface ◽

10.1098/rsif.2012.0107 ◽

2012 ◽

Vol 9 (74) ◽

pp. 2145-2155 ◽

Cited By ~ 57

Author(s):

Deepak K. Pattanayak ◽

Seiji Yamaguchi ◽

Tomiharu Matsushita ◽

Takashi Nakamura ◽

Tadashi Kokubo

Keyword(s):

Surface Charge ◽

Ph Value ◽

Alkaline Solutions ◽

Apatite Formation ◽

Living Body ◽

Heat Treated ◽

Living Bone ◽

Negative Surface ◽

Negative Surface Charge ◽

Main Factor

In order to elucidate the main factor governing the capacity for apatite formation of titanium (Ti), Ti was exposed to HCl or NaOH solutions with different pH values ranging from approximately 0 to 14 and then heat-treated at 600°C. Apatite formed on the metal surface in a simulated body fluid, when Ti was exposed to solutions with a pH less than 1.1 or higher than 13.6, while no apatite formed upon exposure to solutions with an intermediate pH value. The apatite formation on Ti exposed to strongly acidic or alkaline solutions is attributed to the magnitude of the positive or negative surface charge, respectively, while the absence of apatite formation at an intermediate pH is attributed to its neutral surface charge. The positive or negative surface charge was produced by the effect of either the acidic or alkaline ions on Ti, respectively. It is predicted from the present results that the bone bonding of Ti depends upon the pH of the solution to which it is exposed, i.e. Ti forms a bone-like apatite on its surface in the living body and bonds to living bone through the apatite layer upon heat treatment after exposure to a strongly acidic or alkaline solution.

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Bioactive Ti Metal with Ca-Enriched Surface Layer Able to Release Zn Ion

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.529-530.547 ◽

2012 ◽

Vol 529-530 ◽

pp. 547-552 ◽

Cited By ~ 5

Author(s):

Seiji Yamaguchi ◽

Tomiharu Matsushita ◽

Takashi Nakamura ◽

Tadashi Kokubo

Keyword(s):

Body Fluid ◽

Acetic Acid Solution ◽

Calcium Titanate ◽

Mixed Solution ◽

Sodium Hydrogen ◽

Heat Treated ◽

Living Bone ◽

Naoh Solution ◽

Hydrogen Titanate ◽

Surrounding Bone

Preparation of bioactive titanium (Ti) metal able to release Zn2+ ions was attempted by chemical and heat treatments of Ti metal. Ti metal was soaked in 5M NaOH solution at 60 °C to form sodium hydrogen titanate (SHT) on its surface. Then, it was soaked in a mixed solution of 100 mM Ca(CH3COO)2 and 0.01 - 1 mM Zn (CH3COO)2 at 40 °C for 24 h to replace Na+ ions in SHT with Ca2+ and Zn2+ ions at given range of 0.15 to 2.95 in Zn/Ca ratio. When it was heat-treated at 600 °C for 1 h, zinc-incorporated calcium titanate (ZCT) and rutile were formed on the surface of Ti metal. The ZCT partially replaced its Ca2+ and Zn2+ ions with H3O+ ions by subsequent soaking in 1 mM acetic acid solution at 80 °C. Thus treated Ti metal formed apatite on its surface in a simulated body fluid (SBF) within 3 days, and slowly released Zn2+ ions into phosphate-buffered solution (PBS) up to 0.03 ppm. The Ti metal formed with this kind of bioactive ZCT layer on its surface is expected to be useful as orthopedic and dental implants, since it could bond to living bone sooner, by promoting formation of the surrounding bone.

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Morphological Study of Apatite Formation on NaOH- and Heat-Treated Titanium Metal

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.396-398.361 ◽

2008 ◽

Vol 396-398 ◽

pp. 361-364 ◽

Cited By ~ 2

Author(s):

Seiji Yamaguchi ◽

Hiroaki Takadama ◽

Tomiharu Matsushita ◽

Takashi Nakamura ◽

Tadashi Kokubo

Keyword(s):

Cross Section ◽

Body Fluid ◽

Morphological Study ◽

Sodium Titanate ◽

Apatite Formation ◽

Titanium Metal ◽

Sodium Hydrogen ◽

Heat Treated ◽

Living Bone ◽

Hydrogen Titanate

Surface structural change of titanium metal with NaOH and heat treatments and the subsequent soaking in a simulated body fluid (SBF) was investigated by observing cross section of its surface layer by scanning electron microscope. A layer of lathlike phase of sodium hydrogen titanate was formed on the surface of the titanium metal 1 µm in thickness by the NaOH treatment. This was transformed into a layer of lathlike form a little densified of sodium titanate and rutile by the subsequent heat treatment. In SBF, apatite started to precipitate in the interior of the surface lathlike layer, filled the interspaces of the lathlike phases and grew over the surface. This integration of the apatite with the surface lathlike layer might be responsible for the strong bonding of the titanium metal to the living bone.

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Effect of HCl concentrations on apatite-forming ability of NaOH–HCl- and heat-treated titanium metal

Journal of Materials Science Materials in Medicine ◽

10.1007/s10856-009-3815-0 ◽

2009 ◽

Vol 20 (12) ◽

pp. 2401-2411 ◽

Cited By ~ 39

Author(s):

Deepak K. Pattanayak ◽

Takahiro Kawai ◽

Tomiharu Matsushita ◽

Hiroaki Takadama ◽

Takashi Nakamura ◽

...

Keyword(s):

Titanium Metal ◽

Heat Treated

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Bioactivity and Mechanical Property of Starch-Based Organic-Inorganic Hybrids

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.330-332.439 ◽

2007 ◽

Vol 330-332 ◽

pp. 439-442

Author(s):

Toshiki Miyazaki ◽

S. Yasunaga ◽

Eiichi Ishida ◽

Masahiro Ashizuka ◽

Chikara Ohtsuki

Keyword(s):

Mechanical Properties ◽

Calcium Ion ◽

Silanol Group ◽

The Body ◽

Cross Linking ◽

Bioactive Materials ◽

Human Cancellous Bone ◽

Living Bone ◽

Apatite Deposition ◽

High Flexibility

So-called bioactive ceramics bond to living bone through the apatite layer formed on their surfaces in the body. The apatite deposition is triggered by dissolution of calcium ion (Ca2+) and by silanol (Si-OH) group formed on the surfaces of the ceramics. It is expected that organic modification of these components would produce bioactive materials with high flexibility. In this study, we examined bioactivity and mechanical properties of the organic-inorganic hybrids from starch by modification with silanol group and calcium ion. Effect of cross-linking agent was also investigated. The obtained hybrids showed bioactivity and mechanical properties analogous to those of human cancellous bone by appropriate control in their compositions. Addition of cross-linking agent to improve mechanical strength of the hybrids did not decrease their bioactivity.

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