Changes of hyoid, tongue and pharyngeal airway after mandibular setback surgery by intraoral vertical ramus osteotomy.
OBJECTIVE
To assess changes in hyoid, tongue, pharyngeal airway, and head posture in patients who had mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) and to investigate the influence of LeFort I osteotomy.


METHODS
Sixty 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 LeFort I osteotomy. Lateral cephalograms were taken before, immediately after, approximately 1 month after, and at least 1 year after surgery. Parameters indicating the hyoid, tongue, pharyngeal airway, and head posture were evaluated.


RESULTS
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, and the final pharyngeal airway was significantly narrower compared with 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 genders or LeFort I osteotomy after the long-term observation period.


CONCLUSIONS
The hyoid and tongue moved posteriorly after mandibular setback surgery via IVRO, and there was a tendency to relapse back to its original position. However, the final pharyngeal airway width remained narrower after the long-term observation period. Based on our results, careful monitoring of the airway may be needed after mandibular setback surgery via IVRO.
Hwang
Soonshin
S
Department of Orthodontics, Gangnam Severance Dental Hospital, College of Dentistry, Institute of Craniofacial Deformity, Oral Science Research Center, Yonsei University, Seoul, South Korea.
Chung
Chooryung Judi
CJ
Choi
Yoon-Jeong
YJ
Huh
Jong-Ki
JK
Kim
Kyung-Ho
KH
D000402:Airway Obstruction / Q000209:etiology; D002508:Cephalometry; D002574:Cervical Vertebrae / Q000033:anatomy & histology; D016001:Confidence Intervals; D005260:Female; D006257:Head; D006801:Humans; D006928:Hyoid Bone / Q000033:anatomy & histology*; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery*; D008334:Mandible / Q000601:surgery*; D056948:Orthognathic Surgical Procedures / Q000009:adverse effects; D010027:Osteotomy; D019340:Osteotomy, Le Fort; D010614:Pharynx / Q000033:anatomy & histology*; D011187:Posture; D012008:Recurrence; D018709:Statistics, Nonparametric; D014059:Tongue / Q000033:anatomy & histology*; D016896:Treatment Outcome; D055815:Young Adult