3D biomechanical intrusion effects of infra zygomatic bone screws and temporary anchorage device on total maxillary dentition in treatment of vertical maxillary excess: A FEM study

Abstract

Many studies have reported on the application and clinical efficiency of full arch maxillary dentition intrusion mechanics; however, studies about biomechanical effects such as stress, strain, and displacements on the teeth and the surrounding tissues are limited. The objectives of study was to evaluate and compare the stress distribution and displacement of total maxillary dentition under intrusion mechanics using a three-dimensional finite element analysisA three-dimensional finite element model was constructed based on computed tomography scan data, and it served basic model. The geometric model was converted to finite element model using Altair HyperMesh software. Model A with pre-adjusted edgewise appliance (PEA) setup and Model B with occlusal Splint setup was evaluated and compared for von mises stress distribution and displacement of total (full arch) maxillary dentition by using three dimensional finite element analysis; with force delivered from infrazygomatic screws and miniscrew. Force levels for Model A and Model B includes a total of 300grams of intrusive force (each side) on maxillary posterior segment from IZC bone screw and 100grams of intrusive force on anterior segment from miniscrew.In the model A; with PEA setup reinforced with two trans-palatal arches, highest von Mises stress of 0.970 Mpa was produced on second molar roots followed by molar roots and premolars and central and lateral incisors roots. In the Model A, maximum intrusive values was seen on crown tip of central and lateral incisors (8.671µm), and lowest displacement values on second molars (2.230µm). Similar pattern of von Mises stress distribution and displacement was observed in the Model B. Model A and Model B provided an effective en masse vertical control of the full arch maxillary dentition. Higher intrusion displacement values were seen in anterior segment than the posterior segments