Do simultaneous mandibular advancement and temporomandibular joint prosthesis impact the upper airway in TMJ ankylosis patients?

BACKGROUND: Ankylosis of the temporomandibular joint (TMJ) is a pathological disorder which results in patients’ limited or even complete failure of mouth opening. When TMJ ankylosis occurs during the growing age, moderate to severe micrognathia might be the proposed scenario of such cases, accompanied by obstructive sleep apnea and hypopnea syndrome (OSAHS). TMJ reconstruction using total TMJ prostheses with mandibular advancement (MA) can simultaneously improve the function and aesthetic profile of such patients. The purpose of this study was to determine whether the upper airway can be improved after TMJ reconstruction with total TMJ prostheses combined with or without MA in TMJ ankylosis patients. METHODS: Fourteen patients with pre-(T1) and post-(T2) operative CT scans were included. Patients were divided into two groups according to the operation with or without MA (MA/WoMA). The changes of the upper airway and jaw bones were comparatively analyzed within and between the two groups. RESULTS: In MA Group, the volume of the total upper airway (Vt) and palatopharynx (V1), together with the surface area (SA) of the total upper airway (SAt) and palatopharynx (SA1) increased significantly after the operation by 41.4%, 43.2%, 36.3% and 36.6%, respectively. In WoMA Group, V1, SAt and SA1 increased significantly by 21.0%, 19.0% and 23.1% following surgery. The changes of Point B (P<0.01), Y-axis angle (P<0.01), SNB (P<0.01), and ANB (P<0.01) were significantly greater in MA Group than in WoMA Group. Comparing both groups, the maxilla, and mandible were more backward in MA Group than in WoMA group before the operation, but there was no significant difference of the final position of the maxilla and mandible after the operation between both groups. CONCLUSIONS: Release of TMJ ankylosis and condylar reconstruction using total joint prostheses simultaneously with MA could significantly improve the total volume and other various parameters of the upper airway, while, only the dimension of the palatopharynx increased in cases without MA.