RESUMEN
BACKGROUND: Based on excellent hydration ability, the materials for repairing bone defects could be fabricated by three-dimensional printing from amorphous calcium phosphate simply with pure water as adhesive solution; and more importantly, the printed products could be directly used in clinical medicine without high temperature sintering, so amorphous calcium phosphate fits well with technical features of three-dimensional printing. OBJECTIVE: To prepare bone repair materials of amorphous calcium phosphate with mechanical property and printing accuracy to meet practical application requirements by three-dimensional printing. METHODS: Amorphous calcium phosphate used as prototyping powder was prepared by coprecipitation method, and then the viscosity and surface tension of the deionized water as adhesive solution were adjusted by thickening agent and leveling agent, respectively. Afterwards, the three-dimensional printing productions for repairing bone defects were fabricated, and the effects of the viscosity and surface tension of adhesive solution on the forming of droplet, liquid-solid interaction and the mechanical property as well as printing accuracy of three-dimensional printing productions were investigated. RESULTS AND CONCLUSION: By investigating the forming of droplet and liquid-solid interaction, the optimal physicochemical parameters of the adhesive solution were obtained. The viscosity and surface tension of the optimal adhesive solution were 8.0 × 10-3 Pa•s and 40.0 × 10-3 N/m separately, and at this point, not only droplet could form stably and controllably (Z=5.06), but also it smoothly struck the powder layer during spraying (K=14.29), and then it infiltrated into the powder layer uniformly and spread in time (We=36.86). The corresponding three-dimensional printing production has good mechanical properties (compressive strength is 30.4 MPa), high printing accuracy (forming error is 0.9 mm), and a large number of pores indicating good bone conductivity, which partially meets clinical demands of repairing bone defects.