Evaluation of stress and strain on surgical screws and plates in mandibular trunk fractures at different positions of plates and screws: Finite Element Analysis

Abstract

Introduction: To determine the most appropriate method for placement of plates and screws in terms of stress in mandibular body fractures using finite element analysis. Methods: First a model of the mandible reconstructed with Mimics software. This study employed various methods, including plates positioned parallel to the inferior border of the mandible with screws perpendicular to the bone; plates parallel to the inferior border of the mandible fixed with screws oriented at a 45-degree to the fracture line; plates positioned perpendicular to the fracture line fixed with screws perpendicular to the bone; plates perpendicular to the fracture line and fixed with screws oriented at a 45-degree to the fracture line. Then the software measured the stress within the screws and plates in each condition under the maximum bite force. Results: It was observed that in cases of favorable horizontal fractures, the stress exerted on the plates and bones is greater when the plates are aligned parallel to the lower border of mandible, compared to when the plates are positioned perpendicular to the fracture line. In the study of unfavorable horizontal fractures, when the plates were fixed perpendicular to the fracture line, higher magnitudes of stress were recorded compared to the stress observed in the plates positioned parallel to the inferior border of the mandible. Conclusion: In cases of mandibular body fractures with favorable horizontal orientations, the use of fixation techniques involving plates perpendicular to the fracture line is preferred due to the reduced stress exerted on the plates. In the unfavorable horizontal fractures, the stress levels do not exhibit significant variation between different fixations. Finally, it is not advisable to utilize screws positioned at a 45-degree angle to the fracture line, as it can lead to an increase in the displacement of the plates.