3D Finite Element Analysis of the Effects of Lefort I Corticotomy on the Temporomandibular Joint (TMJ) and Maxilla in Skeletal Class III Malocclusion Patients

Abstract

Objective: The purpose of this study was to evaluate the influence of Lefort I corticotomy using two skeletally anchored maxillary protraction protocols on temporomandibular joint (TMJ) and maxilla of skeletal class III malocclusion patients using three-dimensional finite element analysis. Methods: Protraction forces of 500 gm per side were applied on maxilla with two different types of Lefort I corticotomy, type A and type B osteotomy using two skeletally anchored maxillary protraction appliances: skeletally anchored facemask and bone-anchored with class III traction. Results: For the facemask appliance the osteotomy types presented clockwise rotation in contrast with bone-anchored with class III traction which showed counter-clockwise rotation. Within the sagittal plane, the most significant amount of anterior displacement was associated with bone-anchored with class III traction type A osteotomy. For the temporomandibular joint, the maximum stress distribution was concentrated in the anterior aspect condyle and superior aspect of the glenoid fossa for the two appliances. However, the stress distribution in bone-anchored with class III traction was more than skeletally anchored facemask. Conclusion: Using Lefort I corticotomy can be a useful alternative for maxillary protraction in adult patients. Bone anchored with class III traction was more effective for maxillary forward displacement than skeletally anchored facemask. However, the stress distribution on TMJ in bone-anchored was more than that in the facemask. However, the amount of rotation in type A cutting was more than in type B cutting.