School of Dentistry

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Browsing School of Dentistry by Author "Abuzayda, Moosa"

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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.
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    Primary Evaluation of Shape Recovery of Orthodontic Aligners Fabricated from Shape Memory Polymer (A Typodont Study)
    (MDPI, 2021-03-10) Elshazly, Tarek M.; Keilig, Ludger; Alkabani, Yasmine; Ghoneima, Ahmed; Abuzayda, Moosa; Talaat, Sameh; Bourauel, Christoph P.; Orthodontics and Oral Facial Genetics, School of Dentistry
    As an innovative approach to overcome the rate-limiting staging of conventional aligners, using shape memory polymers (SMPs) as aligners’ materials was investigated in this in vitro study. The ability of SMPs to shape recover and consequently move tooth, upon appropriate stimuli, was evaluated on a typodont model before clinical application. The study design was to achieve 1.9 mm correction movement of an upper central incisor by one aligner after multiple steps/activation. A custom-made aligned typodont model with a movable upper central incisor was scanned. Using an orthodontic software and a 3D printer, resin-models were generated. Seven aligners of ClearX sheets (SMPs) were fabricated by thermoforming on the resin aligned model. Each aligner was tested for repositioning of the central incisor in the typodont model. The model was scanned after each step and the corrective movement was measured through the superimposition of scans. Results showed that the total correction efficiency of the SMPs’ aligner was ≈93% (1.76 mm). The corrective movement was 0.94 ± 0.04 mm after the reforming step, 0.66 ± 0.07 mm after the first activation step, and 0.15 ± 0.10 mm after the second activation step. It was concluded that aligners made of SMPs could have a promising future-use in orthodontic aesthetic treatment.