Five-year follow up on risk factors for condylar resorption after maxillomandibular advancement surgery

Limited long-term 3-dimensional (3D) studies exist evaluating risk factors for condylar resorption following orthognathic surgery. Our aim was to evaluate patient demographics, clinical and radiographic characteristics, and orthognathic surgical effects on long-term postoperative condylar volume and height, and horizontal skeletal stability, using a 3D approach. Analysis of clinical data and cone-beam computed tomography before, and approximately two weeks and five years after surgery was carried out on 50 subjects (17 male, 33 female), mean (range) age 25.62 (18-51) years. Multiple significant predictive factors for horizontal skeletal relapse and loss of condylar volume and height were identified which, when combined, were indicative of progressive condylar resorption. The magnitude of mandibular advancement, vertical movement, and preoperative body mass index (BMI) explained 50% of the variance in horizontal skeletal relapse, with mandibular horizontal advancement being the most important factor (31%). Significant predictive factors for long-term loss of condylar volume comprised preoperative BMI and mandibular plane angle, mandibular horizontal advancement, and vertical movement. Loss of condylar height was significantly associated with preoperative condylar volume, condylar neck inclination, and horizontal mandibular advancement. In conclusion, horizontal skeletal relapse and loss of condylar volume and height were affected by multiple predictive factors indicating a multifactorial correlation. The magnitude of mandibular advancement had the largest effect on long-term horizontal skeletal relapse, however, it also had a significant impact on loss of condylar volume and height. Preoperative BMI, mandibular plane angle, condylar volume, condylar neck inclination, and surgical vertical movement were also identified as significant predictive factors for long-term horizontal skeletal relapse and loss of condylar volume and height.