We report a case of Pruzansky grade II hemifacial microsomia, where a patient had improved facial asymmetry with modified simultaneous maxillomandibular distraction, so-called hybrid osteodistraction.
A female patient was diagnosed with first and second branchial arch syndrome and was followed up at another pediatric hospital. She came to our hospital to receive treatment for facial asymmetry with jaw deformity at the age of 9 years. She had right hemifacial microsomia with her chin distorted on the right side. Examination of her oral cavity revealed occlusal plane inclination and an Angle Class II occlusion. The patient underwent corrective surgery at the age of 14 years after pre-surgical orthodontic treatment was finished.
The first step for this corrective surgery involved Le Fort I osteotomy of the maxilla and removal of a 5 mm cuneiform bone fragment of the left side. Next, the left piriform aperture was loosely wired. This step was followed by right horizontal osteotomy and left sagittal osteotomy of the mandibular ramus. The mandible body was advanced 5 mm in order to improve the Angle Class II occlusion, and an intraoral distractor was placed parallel to the right mandibular ramus. From the third day after surgery, the distractor device was lengthened while the occlusion was maintained by intermaxillary fixation. Using this approach, the integrated maxillomandibular bone could be extended on the right side and shortened on the left side as it rotated. Thus, the patient's mandible was gradually distracted in a vertical vector after instantaneous advance. As a result, facial asymmetry and the tilt of the occlusal plane improved with completed functional occlusion.
