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

为了制作人造牙根，我们提出了一种基于过滤操作的形成牙根绿体的新方法。在该方法中，在滤板上放置用于成型的圆柱形模具，在模具的中心部分安装圆柱杆。然后将羟基磷灰石(Hap)-丙酮悬浮液送入模具并过滤，得到环状蛋糕。然后取出棒子，然后过滤氧化铝-丙酮悬浮液。将Hap-Al_2O_3蛋糕在125 Mpa的压力下压缩，在1273~1473K的温度下烧结，从而形成由氧化铝形成的中心轴和牙冠安装部分，而嵌入牙槽骨的部分由Hap形成的人工牙根。X射线衍射和热分析结果表明，在1473K的烧结温度下，氧化铝/Hap连接区发生了部分反应，Hap分解为磷酸钙。EPMA观察表明，铝离子、钙离子和磷离子在接合区几乎没有扩散，接合区的厚度超过几十微米。在1473K下烧结的Hap和Al_2O_3区域的维氏硬度值分别为230和1060(VHN)，沿坯体轴向的抗压强度为86 Mpa。在1473K和122 Mpa热等静压处理1h后，Hap和Al_2O_3区域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.