Finite element analysis on different types of rigid internal fixation for preventing postoperative fractures in cystic lesions of the mandibular angle

Abstract

Objective To build a model of postoperative pathological fracture of the mandibular angular cystic lesions through 3D finite element analysis (FEA), to compare and analyze the biomechanical changes of the mandible after treatment with 8 types of titanium plates, and explore the reliability of titanium plate fixation in preventing pathological fracture of large mandibular cysts. Methods A 30-year-old healthy male was volunteered and the scans of cone beam computed tomography of his mandible were collected to establish a unilateral cystic lesion model of the mandibular angle region to mimic the pathological fracture caused by occlusal force loading. On the basis of the maximum critical cystic lesion size, the biomechanical characteristics and changes in the mandible with 8 different types of titanium plate fixation under the same mechanical conditions were compared. Results The risk of pathological fracture existed when the cystic lesion size in the mandibular angle exceeds 24 mm×30 mm×30 mm. The stress in the lesion area was the lowest when the upper edge was fixed with 1 mm thick titanium plate and bilateral 3 screws, and the lower edge was fixed with 2 mm thick titanium plate and bilateral 4 screws. At the same time the maximum yield strength of the mandible was not exceeded and no pathological fracture of the mandible occurred. Conclusion The incidence of pathological fracture can be reduced by using titanium plate fixation on the upper and lower margins of the mandibular angle after extraoral surgical curettage for large cystic lesions.

Keywords

• cystic lesion of the jaw
• pathological fracture
• rigid internal fixation
• finite element analysis