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{"project":"2_test","denotations":[{"id":"20480036-9068891-52068697","span":{"begin":121,"end":124},"obj":"9068891"},{"id":"20480036-9068891-52068698","span":{"begin":634,"end":637},"obj":"9068891"},{"id":"20480036-15585228-52068699","span":{"begin":813,"end":816},"obj":"15585228"},{"id":"20480036-15585228-52068700","span":{"begin":1273,"end":1276},"obj":"15585228"},{"id":"20480036-10872775-52068701","span":{"begin":2141,"end":2144},"obj":"10872775"},{"id":"20480036-12109700-52068702","span":{"begin":2160,"end":2163},"obj":"12109700"},{"id":"20480036-12109700-52068703","span":{"begin":3055,"end":3058},"obj":"12109700"},{"id":"20480036-15603820-52068704","span":{"begin":3073,"end":3076},"obj":"15603820"},{"id":"20480036-15603820-52068705","span":{"begin":3695,"end":3698},"obj":"15603820"},{"id":"T10646","span":{"begin":121,"end":124},"obj":"9068891"},{"id":"T39323","span":{"begin":634,"end":637},"obj":"9068891"},{"id":"T67875","span":{"begin":813,"end":816},"obj":"15585228"},{"id":"T93316","span":{"begin":1273,"end":1276},"obj":"15585228"},{"id":"T34196","span":{"begin":2141,"end":2144},"obj":"10872775"},{"id":"T41282","span":{"begin":2160,"end":2163},"obj":"12109700"},{"id":"T84398","span":{"begin":3055,"end":3058},"obj":"12109700"},{"id":"T39147","span":{"begin":3073,"end":3076},"obj":"15603820"},{"id":"T85695","span":{"begin":3695,"end":3698},"obj":"15603820"}],"text":"3.4.1. Carbon, Glass, Ceramic Coating\nThe surface of Ti-6Al-4V has been modified by ion beam mixing a thin carbon film [148]. XPS analysis showed that after mixing, the surface film consists essentially of a Ti compound containing (Ti, O, and C), TiO2, Ti, and C. The composition of the surface modified film determined by Rutherford backscattering spectrometry is approximately Ti0.5O0.3C0.2 and its thickness is about 200 μm. It was also reported that after three months immersion in a simulated body fluid, the growth of calcium phosphate species containing both HPO4− and H2PO4− (probably CaHP4 and Ca(PO4)2) have been observed [148]. The corrosion resistance and other surface and biological properties of NiTi were enhanced using carbon plasma immersion ion implantation and deposition (PI3). Poon et al. [149] mentioned that either an ion-mixed amorphous carbon coating fabricated by plasma immersion ion implantation and deposition or direct carbon PI3 can drastically improve the corrosion resistance and block the out-diffusion on Ni from the metal. The tribo-logical tests showed that the treated surfaces are mechanically more superior and cytotoxicity tests revealed that both sets of plasma-treated samples favored adhesion and proliferation of osteoblasts [149]. With regard to potential toxicity of Ni, this is one of methods to prevent or shield the Ni element to diffuse out from NiTi surface. There is another way to achieve the similar outcome by selectively leaching out Ni from the NiTi surface layer by chemically etching the NiTi surface in mixed acid aqueous solution of HF + HNO3 + H2O (1:1:3 by volume) [66].\nBioactive glass (BAG) is a bioactive material with a high potential as implant material. Reactive plasma spraying produces a feasible BAG-coating for Ti-6Al-4V dental implants. It was shown that (i) the coating withstands, without any damage, an externally generated tensile stress of 47 MPa, and (ii) adhesion testing after two months of in vitro reaction in a simulated body fluid showed that coating adhesion strength decreased by 10%, but the implant was still adequate for load-bearing application [150].\nSaiz et al. [151] evaluated the in vitro response in simulated body fluid of silicate glass coating on Ti-6Al-4V. Glasses belonging to the SiO2-CaO-MgO-Na2O-K2O-P2O5 system were used to prepare 50–70 μm thick coatings by employing a simple enameling technique. It has been found that (i) coatings with silica content lower than 60 wt% are more susceptible to corrosion and precipitate carbonated HA on their surface during in vitro tests; however (ii) these coatings have a higher thermal expansion than the metal, (iii), after 2 month in simulated body fluid, crack grows in the coating, reaches the glass/metal interface and initiates delamination, and (iv) glasses with silica content higher than 60wt% are more resistant to corrosion and have lower thermal expansion, and these coatings do not crack, but such glasses with silica do not precipitate apatite even after two months in simulated body fluid [151]. Lee et al. [152] prepared calcium-phosphate, apatite-wollastonite (CaSiO3) (1:3 by volume fraction) glass ceramic, apatite-wollastonite (1:1) glass ceramic, and bioactive CaO-SiO2-B2O3 glass ceramic coatings by the dipping method. Coated and uncoated Ti-6Al-4V screws were inserted into the tibia of 18 adult mongrel male dogs for 2, 4 and 8 weeks. It was found that (i) at 2, 4, and 8 weeks, the extraction torque of these ceramic-coated screws was significantly higher than the corresponding insertion torque, and (ii) strong fixation was observed even at two weeks in all three coatings except CaO-SiO2-B2O3 glass ceramic coating [152]."}

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PMC:2871132 / 69378-73078 JSON TXT