Creation of an Artificial Hydroxyapatite-Alumina Tooth Root by Use of Filtration Method

为了制作人工牙根，我们提出了一种基于过滤操作的牙根绿色体生成新方法。在该方法中，将用于成型的圆柱形模具放置在过滤板上，在模具的中心部分安装圆柱形杆。然后将羟基磷灰石（Hap）-丙酮悬浮液进料到模具中并过滤，得到环形滤饼。然后取出棒，接着过滤氧化铝-丙酮悬浮液。将Hap-氧化铝饼在125 Mpa的压力下压缩并在1273至1473 K的温度下烧结。因此，制造了人造牙根，其中中心轴和牙冠安装部分由氧化铝形成，而嵌入牙槽骨中的部分由Hap形成。X射线衍射和热分析的结果表明，在烧结温度为1473 K的氧化铝/Hap连接区域的部分反应，和Hap的磷酸钙分解观察。EPMA观察表明，在接合区域几乎没有发生铝离子、钙离子或磷离子的扩散，并且接合发生在几十微米的厚度上。在1473 K下烧结的试验体中的Hap和氧化铝区域的维氏硬度值分别为230和1060（VHN），并且沿该体的轴向沿着的压缩强度为86 Mpa。在1473 K和122 MPa下热等静压处理1 h后，Hap区和Al 2 O3区的维氏硬度分别提高到280和1360（VHN），抗压强度提高到160 MPa。

To make an artificial tooth-root, we have proposed a novel method for forming a green body of the root based on filtration operation. In the method, a cylindrical die for molding is put on a filter plate; in the central part of the die a cylindrical rod is installed. Then a hydroxyapatite (Hap)-acetone suspension is fed to the die and filtered, resulting in a toroidal cake. The rod is thereafter removed, followed by filtration of an alumina-acetone suspension. The Hap-alumina cake is compressed under a pressure of 125 Mpa and sintered at a temperature of 1273 to 1473 K. Thus, an artificial tooth-root is created in which the center shaft and crown mounting part are formed from alumina, while the part to be embedded in the alveolar bone is formed from Hap. The results of X-ray diffraction and thermal analysis indicated partial reaction at a sintering temperature of 1473 K in the alumina/Hap joining region, and decomposition of Hap to calcium phosphate was observed. EPMA observations have indicated that almost no diffusion of aluminum ions, calcium ions or phosphorus ions occurred at the joining region, and that joining occurred over a thickness of several tens of micrometers. The Vickers hardness values of the Hap and alumina regions in the test body sintered at 1473 K were 230 and 1060(VHN) respectively, and the compressive strength along the axis of the body was 86 Mpa. When a HIP treatment was carried out for 1 h at 1473 K and 122 Mpa, the Vickers hardness values of the Hap and alumina regions were improved to 280 and 1360 (VHN) respectively, and the compressive strength improved to 160 Mpa.