Three dimensional (3D) forces are the key factors for determining movement of teeth during orthodontic treatment. Designing precise forces and torques on tooth before treatment can result accurate tooth movements, but it is too difficult to realize. In orthodontic biomechanical systems, the periodontal tissues, including bones, teeth, and periodontal ligaments (PDL), are affected by braces, and measuring the forces applied on the teeth by braces should be based on a simulated model composed of these three types of tissues. This study explores the design and fabrication of a simulated oral model for 3D orthodontic force measurements. Based on medical image processing, tissue reconstruction, 3D printing, and PDL simulation and testing, a model for measuring force was designed and fabricated, which can potentially be used for force prediction, design of treatment plans, and precise clinical operation. The experiment illustrated that bi-component silicones with 2:8 ratios had similar mechanical properties to PDL, and with a positioning guide, the teeth were assembled in the mandible sockets accurately, and so a customized oral model for 3D orthodontic force measurement was created.

This paper aims at a simple preparation method of nanocrystalline copper powders through copper sulfate reduction by potassium borohydride in aqueous solution. The product powders obtained in various conditions were investigated by X-ray powder diffraction, transmission electron microscope and particle size distribution analyzer. The parameters that influence the preparation process of copper crystalline were researched, such as the effect of complexing agent, the molar ratio of copper sulfate to potassium borohydride and the quantity of protective polymer. Finally, the preferable reaction conditions were determined, and well-dispersed nanocrystalline copper powders with average diameter of 28.4nm were obtained.