Volumetric changes in the upper airway after bimaxillary surgery for skeletal class III malocclusions: a case series study using 3-dimensional cone-beam computed tomography.
OBJECTIVE
Postsurgical changes of the airway have become a great point of interest and often have been reported to be a predisposing factor for obstructive sleep apnea after mandibular setback surgery. The purpose of this study was to evaluate the 3-dimensional volumetric changes in the upper airway space of patients who underwent bimaxillary surgery to correct Class III malocclusions.


METHODS
This study was performed retrospectively in a group of patients who underwent bimaxillary surgery for Class III malocclusion and had full cone-beam computed tomographic (CBCT) images taken before surgery and 1 day, 3 months, and 6 months after surgery. The upper and lower parts of the airway volume and the diameters of the airway were measured from 2 different levels. Presurgical measurements and the amount of surgical correction were evaluated for their effect on airway volume. Data analyses were performed by analysis of variance and multiple stepwise regression analysis.


RESULTS
The subjects included 21 patients (6 men and 15 women; mean age, 22.7 yrs). The surgeries were Le Fort I impaction (5.27 ± 2.58 mm impaction from the posterior nasal spine) and mandibular setback surgery (9.20 ± 4.60 mm set back from the pogonion). No statistically significant differences were found in the total airway volume for all time points. In contrast, the volume of the upper part showed an increase (12.35%) and the lower part showed a decrease (14.07%), with a statistically significant difference 6 months after surgery (P < .05). Predictor variables affecting the upper and lower parts of the airway volume were presurgical A point to Nasion-perpendicular (A to N-perp) and vertical surgical correction of the pogonion and the posterior nasal spine (P < .05).


CONCLUSIONS
Bimaxillary surgery for the correction of Class III malocclusion affected the morphology by increasing the upper part and decreasing the lower part of the airway, but not the total volume.
Division of Orthodontics, Department of Dentistry, School of Medicine, Ewha Womans University, Seoul, Korea.
Yoonjung
Y
Lee
Youn-Sic
YS
Chun
Nara
N
Kang
Minji
M
Kim
D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000379:methods; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging; D002680:Chin / Q000000981:diagnostic imaging; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004424:Ear Canal / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery*; D008334:Mandible / Q000000981:diagnostic imaging; D063168:Mandibular Osteotomy / Q000379:methods; D008437:Maxilla / Q000000981:diagnostic imaging; D063166:Maxillary Osteotomy / Q000379:methods; D009295:Nasal Bone / Q000000981:diagnostic imaging; D009915:Orbit / Q000000981:diagnostic imaging; D009960:Oropharynx / Q000000981:diagnostic imaging; D056948:Orthognathic Surgical Procedures / Q000379:methods*; D019340:Osteotomy, Le Fort / Q000379:methods; D059229:Osteotomy, Sagittal Split Ramus / Q000379:methods; D010614:Pharynx / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D055815:Young Adult