Investigation of maxillary impacted canine eruption with the aid of two miniscrew-supported and conventional methods with finite element analysis

The aim of this study was to examine the force and stress distributions caused by eruption of the impacted canine via two different anchor mechanics (skeletal and dental) with finite element analysis. Two different models were created using finite element analysis. In both models, the impacted canine is modeled in the maxillary palatal region on the left side. The angle of canine was 45º with the midline. In the first model, 1,5x8 mm titanium miniscrew was placed to the maxillary palatal region on the left side. In the second model, a modified transpalatal arch (TPA) between the first molar teeth by adding a hook was modelled. 100 g of force was applied from the mini-screw in the first model and from the hook on the TPA in the second model to the impacted canine by Ni-Ti spiral springs. In the first model, the compressive and tensile stresses were almost zero since the force was not applied directly and in the second model, the stress concentrated in the first molars and the premolars on the left side. In the first model, the maximum Von Mises stress was observed in the cervix of the miniscrews due to the direct application of the force to the miniscrews. The greatest displacement was observed in the maxillary left quadrant teeth in the second model and while the displacements in the maxillary teeth in the first model was almost zero. Mesiopalatinal rotation in the left first molar, mesial movement in the left quadrant were observed in the second model and distal movement in the impacted canine was found in both models. In the first model, the mini screw provided an absolute anchorage without any adverse dental effect, while TPA may not be sufficient to control the maxillary arch in the three dimension.