Efeito de configurações de attachments na distalização de dentes póstero-superiores com alinhadores: estudo de elementos finitos

Abstract

This study investigated the influence of attachments on distalization of upper posterior teeth using aligners and extra-alveolar orthodontic mini-screw anchorage. A computed tomography scan of an 18-year-old patient with complete permanent dentition and class II division 1 malocclusion was selected. Nine finite element models of the upper arch containing aligners and mini-screw anchorage were constructed to simulate the distalization of the second molar, altering attachment configurations (NA, no attachments; VA, vertical attachments; VHA, vertical + horizontal attachments) and devices for force application on the canine (BT, button; HO, hook; and PC, precision cut). Displacements were measured with reference to the mesiobuccal cusp tip of second molar, the cusp tip of canine, and the incisal edge of upper central incisor in the sagittal (Y-axis), vertical (Z axis), and coronal (X-axis) planes. In the sagittal axis, the second molar exhibited distal movement, as the canine and central incisor displayed buccal movement, with a tendency for models with VHA and VA to have greater buccal movement of anterior teeth. In the vertical axis, the teeth showed a tendency for intrusion, except for the VA+PC model, which tended to evident extrusion. In the coronal axis, the second molar tended to lingualize, and the anterior teeth to mesialize, except for the central incisor in the VA+PC model, which presented distalization. Therefore, not using attachments seems the best option, regardless of the anchorage device on the canine; using attachments, regardless of configuration, tends to increase vestibular movement of the anterior teeth, which is unfavorable for treatment.