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Abstract：
Interfaces between AISI 304 stainless steel screws and cranial bone were investigated after long-term implantation lasting for 42 years. Samples containing the interface regions were analyzed using state-of-the-art analytical techniques including secondary ion mass, Fourier-transform infrared, Raman, and X-ray photoelectron spectroscopies. Local samples for scanning transmission electron microscopy were cut from the interface regions using the focused ion beam technique. A chemical composition across the interface was recorded in length scales covering micrometric and nanometric resolutions and relevant differences were found between peri-implant and the distant cranial bone, indicating generally younger bone tissue in the peri-implant area. Furthermore, the energy dispersive spectroscopy revealed an 80 nm thick steel surface layer enriched by oxygen suggesting that the AISI 304 material undergoes a corrosion attack. The attack is associated with transport of metallic ions, namely, ferrous and ferric iron, into the bone layer adjacent to the implant. The results comply with an anticipated interplay between released iron ions and osteoclast proliferation. The interplay gives rise to an autocatalytic process in which the iron ions stimulate the osteoclast activity while a formation of fresh bone resorption sites boosts the corrosion process through interactions between acidic osteoclast extracellular compartments and the implant surface. The autocatalytic process thus may account for an accelerated turnover of the peri-implant bone.
摘要：
经过持续42年的长期植入，研究了AISI304不锈钢螺钉与颅骨之间的界面。使用最先进的分析技术分析包含界面区域的样品，包括二次离子质量，傅里叶变换红外,拉曼,和X射线光电子能谱。使用聚焦离子束技术从界面区域切割用于扫描透射电子显微镜的局部样品。以涵盖微米和纳米级分辨率的长度尺度记录了整个界面的化学成分，并且在植入物周围和远端颅骨之间发现了相关差异，表明种植体周围区域通常较年轻的骨组织。此外，能量色散光谱显示出80nm厚的富含氧的钢表面层，表明AISI304材料经历了腐蚀攻击。攻击与金属离子的运输有关，即,亚铁和三价铁，进入邻近植入物的骨层。结果符合释放的铁离子和破骨细胞增殖之间的预期相互作用。相互作用产生自催化过程,其中铁离子刺激破骨细胞活性,而新鲜骨吸收位点的形成通过酸性破骨细胞细胞外区室与植入物表面之间的相互作用促进腐蚀过程。因此,自催化过程可导致种植体周围骨的加速周转。
