Stability of orthognathic surgery and condylar resorption in mild craniofacial microsomia compared to non-syndromic Class II asymmetry

This study was performed to compare skeletal stability and condylar resorption after bimaxillary surgery between adults with mild craniofacial microsomia (CFM) and those with non-syndromic skeletal Class II asymmetry. Cone-beam computed tomography images of two groups were analysed: CFM group (n = 20), Class II group (n = 20). Voxel- and landmark-based methods were used to quantify the translation and rotation of osteotomy segments during surgery and at follow-up. Changes in condylar volume were measured at follow-up. Compared to the Class II group, the surgical movements were significantly larger in the CFM group for several parameters (P < 0.05). The maxilla demonstrated similarly good stability in the CFM group as in the Class II group, except at A-point (P = 0.024). Similarly good stability in mandibular projection was also observed in the CFM group. Regarding symmetry, less stability was found on the non-affected side of the mandibular body in the CFM group (sagittal, P = 0.038; vertical, P = 0.018) and in the anterior mandible in the Class II group (P = 0.56; clinically relevant). The CFM group showed significantly less condylar resorption on the affected side (P = 0.042). In conclusion, the stability of mild CFM was clinically good and not inferior to that of non-CFM Class II asymmetry, despite the greater surgical movements in CFM. Moreover, the hypoplastic condyles in CFM were not vulnerable to resorption.