In this study, we proposed a powder-layered manufacturing process, a type of rapid prototyping technique, to produce desired bone shapes for transplants using biomaterial powder. In the experiments, we used conventional inkjet-type equipment and orthopedic filling-paste powder (BIOPEX), mainly containing alpha-tribasic calcium phosphate as the forming material. To solidify the powder, we used a sodium chondroitin sulfate + dibasic sodium succinate anhydride aqueous solution as the binder liquid. This paper discusses the results of investigations on the internal and surface chemical characteristics of formed artificial bones, formed artificial bones hardened by immersion process, and paste type artificial bones used in clinical applications, to determine the suitability of the immersion conditions. The bones were immersed for five hours in immersion fluid made of water and binder liquid at 90°C. To analyze the chemical constituent, X-ray diffraction and X-ray photoelectron spectroscopy were used. The results showed that the hydrate reaction caused by the application of the binder fluid during forming enhances hydroxyapatite (HA) concentration by about 6.5 times. With samples immersed in water, HA was found internally as well as from the surface, the quantity of which was about 80%, 11 times more than conventional paste type artificial bone. On the other hand, with the samples immersed in the binder fluid, no HA crystals were detected internally. The percentages of P and Ca present on the surface were minute. Given the high quantities of C, O, and Na present, the immersion process is thought to have formed a thin layer of binder fluid. These results from the experimental samples indicate that immersion in binder fluid which showed no problems in terms of chemistry and strength is most appropriate for clinical applications.
