Examination of changes in the pharyngeal airway space under anterior traction of the mandible: Influence of detachment of the periosteum during orthognathic surgery

ObjectiveMaxillo-mandibular advancement (MMA) has attracted attention as a treatment for obstructive sleep apnea syndrome (OSAS) in recent years. We previously evaluated the breathing status during sleep before and after orthognathic surgery and found that maxillary advancement has a greater effect compared with mandibular advancement (J Jaw Deform 2007;17:9–15). The pharyngeal air space, however, exists within the soft tissue surrounded by the jaw bone and the cervical spine, and it can easily be speculated that mandibular advancement will affect its morphology. In this study, changes in the pharyngeal air space before and after periosteal detachment of the inferior and posterior margin of the distal bone fragment of the mandible were investigated.Subjects and methodsThe subjects were orthognathic surgery patients whose chief complaint was malocclusion. We compared the pharyngeal air space before and after detachment of the periosteum in the same patients. The evaluation method measured the anteroposterior diameter of the pharyngeal air space under endoscopy during anterior traction of the mandible.Results and discussionThe anterior range of motion of the mandible increased after the periosteal detachment. Compared with the periosteum before detachment, there was a tendency for the pharyngeal air space not to be enlarged with mandibular advancement after the detachment. These results show that detachment of the periosteum distal bone fragment during mandibular advancement maintains the pharyngeal airway space. Therefore the change would not appear to affect the sleep breathing status.