Browsing by Subject "Biomaterial"

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    Determining the Effects of Varying Blood Storage Conditions on Clot Formation and Digestion Under Shear
    (Wiley, 2024) Christodoulides, Alexei; Zeng, Ziqian; Hall, Abigail R.; Alves, Nathan J.; Emergency Medicine, School of Medicine
    Studies aiming to understand the effects of storage on whole blood clotting often rely on characterizing coagulation under static conditions. Minimal work has explored the effects of physiologic shear on clot formation and thrombolysis utilizing fractionated and reconstituted whole blood products. Whole blood (WB) was fractionated into platelet free plasma (PFP), packed red blood cells (pRBCs), and platelets storing each component under its ideal conditions - including platelet cryopreservation. Recombination at their native ratios was accomplished over 91-days of storage and clotting/thrombolysis was analyzed utilizing thromboelastography (TEG) and Chandler loop. Reconstituted whole blood (rWB) preserved clot strength through 91 days with minimal deviation from baseline, in contrast to WB stored at 4°C which experienced a significant decline by storage day-42. Clot formation under shear for both rWB and WB led to increased clot mass through storage. No significant deviation from baseline was appreciated until day-70 of storage in rWB. Increasing degrees of thrombolysis were seen in both groups, with rWB significantly deviating from baseline at day-70. No significant changes in overall clot architecture occurred throughout storage and recombination. This fractionation and recombination protocol serves as a method to further develop reproducible in vitro clot analogs for preclinical thrombolytic therapy screening.
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    Potential Application of 4D Technology in Fabrication of Orthodontic Aligners
    (Frontiers Media, 2022) Elshazly, Tarek M.; Keilig, Ludger; Alkabani, Yasmine; Ghoneima, Ahmed; Abuzayda, Moosa; Talaat, Wael; Talaat, Sameh; Bourauel, Christoph P.; Orthodontics and Oral Facial Genetics, School of Dentistry
    Objectives: To investigate and quantify forces generated by three-dimensional-printed aligners made of shape memory polymers (four-dimensional [4D] aligner). Methods: Clear X v1.1 material was used in this study. On a custom-made typodont model, correction of maxillary central incisor (tooth 21) malposition by 4D aligners with thicknesses of 0.8 and 1.0 mm was measured by superimposition of subsequent scans. Maximum deflection forces generated by foil sheet specimens were measured at different temperatures in three-point bending (3-PB) tests. In a biomechanical system (orthodontic measurement and simulation system [OMSS]), forces generated on movements of tooth 21 by the 4D aligners were measured at different temperatures. Results: 4D aligners succeeded to achieve a significant tooth movement (2.5 ± 0.5 mm) on the typodont, with insignificant difference between different thicknesses. In the 3-PB test, the maximum deflection forces measured at 20, 30, 37, 45, and 55°C, were 3.8 ± 1.1, 2.5 ± 0.9, 1.7 ± 0.6, 1.0 ± 0.4, and 0.5 ± 0.4 N, respectively. Forces delivered on palatal displacement of tooth 21 at 37, 45, and 55°C by 0.8-mm aligners were 0.3 ± 0.1, 0.2 ± 0.1, and 0.7 ± 0.2 N, respectively, whereas those by 1.0-mm aligners were 0.3 ± 0.1, 0.3 ± 0.1, and 0.6 ± 0.2 N, respectively. A good concordance with movement on the typodont model was shown in OMSS. Conclusion: An initial study of 4D-printed aligner shows its ability to move a tooth by biocompatible orthodontic forces, after a suitable thermal stimulus within the oral temperature range.