Do different orthodontic archwires alter the biomechanical effects of open coil springs on dentoalveolar structures? A finite element analysis.

BACKGROUND

In this study, the effect of open-arch mechanics on the displacement and von Mises stress distributions in mandibular teeth was investigated using a finite element analysis.

METHODS

After mandibular bone, teeth, and periodontal ligament formation, 0.022-in brackets and 0.016 × 0.022-in tubes were placed on the buccal equatorial line. Four scenarios were modeled using 2 materials (nickel-titanium [NiTi] and stainless steel [SS]) and 2 arch wire sizes (0.016-in and 0.016 × 0.022-in). Displacement and von Mises stresses were analyzed via finite element analysis (Algor Fempro, ALGOR Inc, Pittsburgh, Pa) in models including teeth up to the second molar, with the mandibular left first premolar missing.

RESULTS

The highest von Mises stress was found in the 0.016-in NiTi wire, and the lowest in the 0.016-in SS wire. Across scenarios, peak root surface stress was at the apical region of the mandibular left second premolar, whereas the highest periodontal ligament stress was in its gingival third. The buccal tubercle of this tooth showed the greatest displacement. Among archwires, the highest stress occurred in the 0.016-in SS wire.

CONCLUSIONS

Von Mises stresses decreased with distance from the missing tooth site. The highest stress occurred at the apical end of the mandibular left second premolar. Except for the 0.016-in round NiTi wire, this tooth showed the greatest tubercle apex displacement. In all scenarios, except the mandibular left first molar, mesial root stresses were greater in the mandibular roots than in the distal roots.