Miniscrew ; Three-dimensional finite element analysis ; Mandibular anterior segment intrusion ; Stress distribution
Abstract
Objective: The purpose of this study was to analyze the stress distribution and the displacement pattern of mandibular
anterior teeth under various intrusive force vectors according to the position of orthodontic miniscrews
and hooks, using three-dimensional finite element analysis. Methods: A three-dimensional finite element model
was constructed to simulate mandibular teeth, periodontal ligament, and alveolar bone. The displacement of individual
tooth on three-dimensional planes and the von Mises stress distribution were compared when various
intrusion force vectors were applied. Results: Intrusive forces applied to 4 mandibular anterior teeth largely resulted
in remarkable labial tipping of the segment according to the miniscrew position. All 6 mandibular anterior
teeth were labially tipped and the stress concentrated on the labiogingival area by intrusive force from miniscrews
placed mesial to the canine. The distointrusive force vector led to pure intrusion and the stress was evenly distributed
in the whole periodontal ligament when the hook was placed between the central and lateral incisors
and the miniscrew was placed distal to the canine. Conclusions: Within the limits of this study, it can be concluded
that predictable pure intrusion of the 6 anterior teeth segment may be accomplished using miniscrews
placed distal to the canine and hooks located between the central and lateral incisors.