Kokubo Tadashi, Yamaguchi Seiji
Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University 1200 Matsumoto-chow, Kasugai, Aichi 487-8501 Japan.
Open Biomed Eng J. 2015 Feb 27;9:29-41. doi: 10.2174/1874120701509010029. eCollection 2015.
To reveal general principles for obtaining bone-bonding bioactive metallic titanium, Ti metal was heat-treated after exposure to a solution with different pH. The material formed an apatite layer at its surface in simulated body fluid when heat-treated after exposure to a strong acid or alkali solution, because it formed a positively charged titanium oxide and negatively charged sodium titanate film on its surface, respectively. Such treated these Ti metals tightly bonded to living bone. Porous Ti metal heat-treated after exposure to an acidic solution exhibited not only osteoconductive, but also osteoinductive behavior. Porous Ti metal exposed to an alkaline solution also exhibits osteoconductivity as well as osteoinductivity, if it was subsequently subjected to acid and heat treatments. These acid and heat treatments were not effective for most Ti-based alloys. However, even those alloys exhibited apatite formation when they were subjected to acid and heat treatment after a NaOH treatment, since the alloying elements were removed from the surface by the latter. The NaOH and heat treatments were also not effective for Ti-Zr-Nb-Ta alloys. These alloys displayed apatite formation when subjected to CaCl2 treatment after NaOH treatment, forming Ca-deficient calcium titanate at their surfaces after subsequent heat and hot water treatments. The bioactive Ti metal subjected to NaOH and heat treatments has been clinically used as an artificial hip joint material in Japan since 2007. A porous Ti metal subjected to NaOH, HCl and heat treatments has successfully undergone clinical trials as a spinal fusion device.
为了揭示获得具有骨结合能力的生物活性金属钛的一般原理，对钛金属在暴露于不同pH值的溶液后进行了热处理。当在暴露于强酸或强碱溶液后进行热处理时，该材料在模拟体液中其表面形成了磷灰石层，这是因为它分别在其表面形成了带正电荷的氧化钛和带负电荷的钛酸钠薄膜。经过这样处理的这些钛金属与活骨紧密结合。暴露于酸性溶液后进行热处理的多孔钛金属不仅表现出骨传导性，还表现出骨诱导行为。暴露于碱性溶液的多孔钛金属如果随后进行酸处理和热处理，也表现出骨传导性和骨诱导性。这些酸处理和热处理对大多数钛基合金无效。然而，即使是那些合金在经过氢氧化钠处理后再进行酸处理和热处理时也会形成磷灰石，因为合金元素被氢氧化钠处理从表面去除了。氢氧化钠处理和热处理对Ti-Zr-Nb-Ta合金也无效。这些合金在氢氧化钠处理后进行氯化钙处理，随后经过热处理和热水处理后在其表面形成缺钙钛酸钙时会显示出磷灰石形成。经过氢氧化钠处理和热处理的生物活性钛金属自2007年以来在日本已被临床用作人工髋关节材料。经过氢氧化钠、盐酸和热处理的多孔钛金属作为脊柱融合装置已成功进行了临床试验。
