Evaluation of stresses and displacement in the craniofacial region as a reaction to bone-anchored maxillary protraction in conjugation with posterior bite plane and rapid maxillary expansion in patients with Class III malocclusion: A finite element analysis study

Abstract

Introduction: Treating a Class III malocclusion is often challenging for orthodontists. Bone-anchored maxillary protraction (BAMP) is known for achieving a significant maxillary protraction. The study aimed to evaluate the stress distribution and displacement of craniofacial bones as a reaction to the forces of BAMP, along with rapid maxillary expander and the posterior bite plane, in growing patients with skeletal Class III malocclusion using a finite element method.

Methods: An finite element model was constructed from the spiral computed tomographic images of a skull from an 11-year-old growing patient with skeletal Class III malocclusion along with BAMP, rapid maxillary expander, and the posterior bite plane. The created model had 105,189 nodes and 481,066 elements. After assigning the appropriate material properties and the boundary condition, 800 g of transverse force per side and a Class III intraoral elastic 250 g of force per side were applied to the model, and after the postprocessing, the results were obtained in the form of color bands.

Results: The maxilla and the attached structures were displaced and expanded transversely. The maxilla was displaced anteriorly by 0.692 mm, and the mandible was displaced backward by 0.204 mm in the sagittal direction. The anterior region of the maxilla and mandible, dentition, and nasal bone were rotated counterclockwise. Displacement in an upward direction was greatest at the symphysis region of the mandible. The stresses experienced by most of the bones were tensile, with the maxilla and maxillary dentition experiencing the maximum.

Conclusions: Favorable changes were appreciated with maxillary forward and mandibular backward displacement, with appreciable tensile stresses in all the bones.