Chang C K, Wu J S, Mao D L, Ding C X
Open Laboratory for High Temperature Materials and High Temperature Tests, Shanghai Jiao Tong University, P.R. China.
J Biomed Mater Res. 2001 Jul;56(1):17-23. doi: 10.1002/1097-4636(200107)56:1<17::aid-jbm1063>3.0.co;2-t.
This paper evaluates the behavior of hydroxyapatite (HAP) coated and noncoated Ti6Al4V implants in dog tibia after 3 and 5 months implantation. HPA-coated implants were obtained by plasma spraying. XRD, SEM, and EPMA were employed to estimate the coating characteristics and their behavior in vivo. Investigation of material characteristics showed that the as-received coatings consisted mainly of amorphism and HAP phase. Other phases such as TCP and CaO were identified due to thermal changes of HAP particles in plasma flame. SEM micrographs showed a typical microstructure of plasma-sprayed coating. The as-received coating was formed by well-melted pancake-like splats that lead to a dense coating with a rough surface. Lamellar structure, micropores, and microcracks, observed inside the coating, are characteristic of plasma spraying. Push-out tests revealed that HAP coating had a significant promotion of interfacial shear strength. The shear strength between bone and HAP-coated implants was much higher than that between bone and noncoated implants due to the different bone-implant interfaces formed after implantation. SEM observation revealed a direct attachment between HAP coating and newly formed bone. However, noncoated implants were separated from newly formed bone by fibrous tissues. Ti ions were found to be released into the surrounding environment after long time immersion in body fluid, and thus caused low shear strength. Prolongation of implantation time had different effects on shear strength. It improved the shear strength between HAP-coated implant and newly formed bone. However, it had little effect on that between noncoated implant and surrounding tissues.
本文评估了羟基磷灰石（HAP）涂层和未涂层的Ti6Al4V植入物在犬胫骨中植入3个月和5个月后的行为。HPA涂层植入物通过等离子喷涂获得。采用X射线衍射（XRD）、扫描电子显微镜（SEM）和电子探针微分析（EPMA）来评估涂层特性及其在体内的行为。材料特性研究表明，接收的涂层主要由非晶态和HAP相组成。由于等离子火焰中HAP颗粒的热变化，还鉴定出了其他相，如磷酸三钙（TCP）和氧化钙（CaO）。SEM显微照片显示了等离子喷涂涂层的典型微观结构。接收的涂层由充分熔化的薄饼状扁平颗粒形成，形成了致密且表面粗糙的涂层。涂层内部观察到的层状结构、微孔和微裂纹是等离子喷涂的特征。推出试验表明，HAP涂层显著提高了界面剪切强度。由于植入后形成的骨 - 植入物界面不同，骨与HAP涂层植入物之间的剪切强度远高于骨与未涂层植入物之间的剪切强度。SEM观察显示HAP涂层与新形成的骨之间存在直接附着。然而，未涂层的植入物被纤维组织与新形成的骨隔开。发现Ti离子在长时间浸入体液后会释放到周围环境中，从而导致剪切强度较低。延长植入时间对剪切强度有不同影响。它提高了HAP涂层植入物与新形成的骨之间的剪切强度。然而，对未涂层植入物与周围组织之间的剪切强度影响不大。
