A finite element analysis of the effects of different skeletal protraction and expansion methods used in class III malocclusion treatment

Abstract

This study aims to carry out an in-silico examination of the different skeletal advancement methods used in the treatment of maxillary retrusion patients. Computed tomography images of a young adolescent patient with maxillary retrusion were processed using three-dimensional medical image processing software to obtain a patient-specific model. Three different treatment scenarios were envisaged for the finite element analysis. In the first scenario, rapid maxillary expansion (RME) and face mask (FM); in the second, bone-assisted maxillary advancement and RME, and in the third, hybrid hyrax+mentoplate combination method were used. The hyrax screw was activated by 0.25mm in each model, with a force of 500g in the first scenario and 250g in the second and third scenario for each side. Von Mises stresses and the initial displacements were evaluated when different maxillary protraction methods were applied. We found that similar stress distributions were observed in the skull where the methods of RME/FM model and bone-assisted maxillary advancement were used. These stresses were higher than the hybrid hyrax+mentoplate combination method. When the displacement values were compared, anterior movement was found in the maxilla in the bone-supported model to include the middle face, while maxillary anterior movement of maxilla was detected on the Le Fort 1 level with the hybrid hyrax+mentoplate combination method. Dentoalveolar anterior movement was detected in the RME/FM model. Given the obtained stress distributions and displacement values, it has been observed that the bone-assisted maxillary advancement method provides more skeletal efficiency than the RME/FM and the hybrid hyrax+mentoplate combination methods. [Med-Science 2018; 7(4.000): 898-904]

Keywords

• Finite element
• Class III
• mentoplate
• hybrid hyrax
• facemask