Effect of Bracket Slot and Archwire Dimension on Posterior Tooth Movement in Sliding Mechanics: A Three-dimensional Finite Element Analysis

Abstract

IntroductionSpace closure by molar protraction has always been a challenge in orthodontic treatment due to larger root surface area which requires additional anchorage. Ideally, there should be little or no tipping. However, the protraction forces, being occlusal and buccal to the centre of resistance (CR) of the tooth, cause tipping and rotations.AimThe aim of the study was to assess the effect of bracket slot and archwire dimensions on posterior tooth movement during space closure in sliding mechanics and evaluate the length of power arm to bring about translatory movement of teeth using three-dimensional finite element analysis.Materials and methodsA model of the maxillary teeth was created and converted to a finite element format through a meshing software, Hypermesh. Two three-dimensional models, each with a combination of 0.017”× 0.022” archwire in 0.018” slot (model 1) and 0.019”×0.025” archwire in 0.022” slot (model 2), were generated. Power arms of different lengths were attached to the first molar. Miniscrew was inserted between the canine and first premolar.ResultsIn model one, the power arm of 10-mm height provided controlled tooth movement than the one with 6 mm height, and in model two, power arms of both 6-mm and 10-mm height produced controlled tooth movement.ConclusionsAs the force was raised apically from the slot, more translation was observed. Power arm of 6-mm height can be used due to anatomic limitation of the vestibule.

Fricción de brackets autoligado y convencionales en el cierre de espacios: revisión de la literatura

“…El cierre de espacios por medio de mecánica de deslizamiento sugirió ser más eficiente con diferencia clínica 1,5 meses con el uso de brackets con ranura 0.018 en comparación 0.022 (do Nascimento et al, 2020). En un estudio de elementos finitos tridimensional para el cierre de espacio por protracción de molar superior en diferentes tamaño de ranuras del brackets (0.018", 0.022"), más un brazo de poder en diferentes longitudes (2, 6, 10 mm) , con arco de acero inoxidable y como anclaje un miniimplante de 2,3 mm de diámetro por 8 mm de longitud colocado entre canino y premolar, concluyeron que en la ranura 0.018" (arco de acero 0.017x0.025) y brazo de poder de 10 mm fue equivalente al modelo con ranura 0.022" (arco de acero 0.019 x0.025) y brazo de poder de 6 mm, como resultado un movimiento controlado del molar (Ahmed et al, 2019). No se encontró estudios de la variación del tamaño de la ranura en los brackets autoligado y convencionales.…”