Design and localization algorithm of flap guide plate for jaw defect based on digital 3D printing

The anterolateral thigh flap is often used to repair the wound tissue defect. Because it is difficult to carry out the perforating vessels before and after the operation, it is considered to use digital design combined with 3D printing technology to prepare the digital three-dimensional guide plate, and at the same time, the guide plate positioning algorithm is designed according to the error caused by the different placement of the guide plate at the site to be transplanted. First of all, select the patients with jaw defect, make the patient's jaw model, obtain the corresponding plaster working model through 3D scanning, obtain STL data, design the guide plate in combination with Rihnoceros and other software, and print the flap guide plate corresponding to jaw defect with the help of metal powder using 3D printer. Based on sequential CT images, the localization algorithm takes the improved genetic algorithm as the research object, extracts the information of the transplantation area as the parameter space, codes the parameters such as the coordinates of the end points of the flap transplantation, and constructs the target function and fitness function of the transplantation. In the experiment, the soft tissue of the patients with jaw defects can be well repaired based on the guide plate. The positioning algorithm locates the flap graft under the condition of less environmental parameters, and obtains the corresponding diameter parameters.

Impacts of residual 3D printing metal powders on immunological response and bone regeneration: an in vivo study

Residual powder is a defect in powder bed fusion-based additive manufacturing (3D printing), and it is difficult to completely remove it from as-printed materials. In addition, it is not necessary to apply 3D printed implants with residual powder in the clinic. The immunological response triggered by the residual powder is an important area of study in medical research. To further understand the possible immunological reactions and hidden dangers caused by residual powders in vivo, this study compared the immunological reactions and osteolysis caused by typical powders for four implant materials: 316 L stainless steel, CoCrMo, CP-Ti, and Ti-6Al-4V (particle size range of 15-45 μm), in a mouse skull model. Furthermore, the possible immunological responses and bone regeneration induced by the four 3D printed implants with residual powder in a rat femur model were compared. In the mouse skull model, it was found that the 316L-S, CoCrMo-S, and especially the 316L-M powders, upregulated the expression of pro-inflammatory factors, increased the ratio of RANKL/OPG, and activated more functional osteoclasts, resulting in more severe bone resorption compared with those in other groups. In the rat femur model, which is more suitable for clinical practice, there is no bone resorption in implants with residual powders, but they show good bone regeneration and integration ability because of their original roughness. The results indicate that the expressions of inflammatory cytokines in all experimental groups were the same as those in the control group, showing good biological safety. The results answered some critical questions related to additively manufactured medical materials in vivo and indicated that as-printed implants may have great potential in future clinical applications.

Fabrication of Al and Al-Si alloy microspheres by ultrasonic irradiating the molten salt-aluminum immiscible system

Microspheres of pure aluminum and Al-7wt%Si alloy were successfully fabricated by ultrasonic irradiating the molten NaCl-KCl-Al and NaCl-KCl-(Al-Si) systems respectively. Ultrasonic cavitation is mainly responsible for the formation of metal microspheres. A minimum diameter of ∼15 μm of the microspheres can be achieved. The final morphology and size of the metal spheres are determined by both the irradiation process and the subsequent solidification condition. Under the protection of molten salt, this process provides a novel way to fabricate spherical metal powder that has relative high activity and melting point.

A large dataset of synthetic SEM images of powder materials and their ground truth 3D structures

This data article presents a data set comprised of 2048 synthetic scanning electron microscope (SEM) images of powder materials and descriptions of the corresponding 3D structures that they represent. These images were created using open source rendering software, and the generating scripts are included with the data set. Eight particle size distributions are represented with 256 independent images from each. The particle size distributions are relatively similar to each other, so that the dataset offers a useful benchmark to assess the fidelity of image analysis techniques. The characteristics of the PSDs and the resulting images are described and analyzed in more detail in the research article "Characterizing powder materials using keypoint-based computer vision methods" (B.L. DeCost, E.A. Holm, 2016) [1]. These data are freely available in a Mendeley Data archive "A large dataset of synthetic SEM images of powder materials and their ground truth 3D structures" (B.L. DeCost, E.A. Holm, 2016) located at http://dx.doi.org/10.17632/tj4syyj9mr.1[2] for any academic, educational, or research purposes.