Browsing by Subject "Tooth movement"

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    Effects of minor tooth movements on occlusal forces
    (2014-07-15) Hernandez-Garcia, Manuel B.; Katona, Thomas R.; Eckert, George J.
    SUMMARY The aim of this study was to assess if minor tooth shifts, common with dental restorations and during orthodontic treatment, can substantially affect occlusal contact forces. Matched pairs of Dentsply Portrait IPN denture teeth with cuspal angulations of 0°, 20°, 33° and 40° were brought into occlusion by a weighted maxillary tooth. Each pair of teeth was positioned in three interocclusal molar relationships (Angle Class I, Class II and Class III) and 5 relative angulations, for a total of 60 control measurements. From each control position, the mandibular tooth, supported by a load cell, was moved 0.2 mm to the mesial, and in turn, 0.2 mm to the buccal. In each configuration, the three-dimensional loads (3 force and 3 moment components) on the lower tooth were measured by the load cell. It was found that the 0.2 mm tooth shifts substantially affected the occlusal contact forces with all interocclusal configurations and cusps. Current clinical concepts and guidelines oversimplify the complexity of the interactions of occlusal contact forces. Because the relationships between occlusal anatomy and tooth loads are so complex, more investigations are needed to establish the full extent of their potential clinical implications.
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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.