Abstract: Objective: To explore the factors related to the failure of mandibular angle fractures treated by internal fixation on the external oblique. Methods: A retrospective analysis was performed on 39 cases of mandibular angle fractures treated with internal fixation on the external oblique line from January 2013 to October 2023. The patients were divided into the successful group and the failed group according to the image at postoperative review, and compared in terms of age, gender, combined medical diseases, combined multiple fractures, combined mandibular third molar, time from injury to surgery, postoperative infection, postoperative bite relationship, poor bite relationship, and other factors. Results: All patients were followed up for more than 1 year, and 6 patients (15.38%) had internal fixation failure after surgery, including 2 cases of titanium nail drift, 2 cases of fracture suture enlargement, 1 case of internal fixation fracture, and 1 case of fracture end dislocation. The fractures of the remaining patients were healed. The results of univariate analysis showed that there were differences between the successful and failed groups in the combination of multiple fractures, postoperative infection, and poor recovery of postoperative occlusal relationship. Conclusion: The failure rate of mandibular angle fracture fixed on the lateral oblique line is still high. Patients with multiple fractures need to be carefully evaluated and determined before surgery. Attention should be paid to prevent wound infection after surgery, and intermaxillary traction should be persisted to adjust the occlusion, so as to reduce the failure rate of postoperative internal fixation.

Key words: mandibular angle fracture, internal fixation failure, risk factors