Changes of hyoid and tongue position after mandibular setback surgery by intraoral vertical ramus osteotomy

Abstract

The aim of this study was to assess changes in hyoid, tongue position, oropharyngeal airway and head posture in patients who had mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) and to investigate the influence of Le Fort I osteotomy.60 patients with skeletal Class III malocclusion were evaluated. All patients had mandibular setback surgery via IVRO and 45 patients had additional maxillary impaction surgery via Le Fort I osteotomy. Lateral cephalograms were taken before (T1), immediately after (T2), approximately 1 month after (T3), and at least 1 year after (T4) surgery. Parameters indicating the hyoid, tongue position and head posture were evaluated. The hyoid significantly moved inferoposteriorly immediately after surgery and relapsed superoanteriorly during observation periods. The tongue significantly moved posteriorly during all periods. The final position of the hyoid and tongue was significantly posterior compared to its presurgical position. Significant cervical hyperflection occurred during observation periods and was strongly correlated with anterior movement of the hyoid. The hyoid and tongue showed similar positions regardless of the presence of different factors such as gender or Le Fort I osteotomy after the long term observation period.The hyoid and tongue moved posteriorly after mandibular setback surgery via IVRO. However, there was a tendency to relapse back to its original position in the long term observation period. Based on our results, careful monitoring of the airway maybe needed after mandibular setback surgery via IVRO.