A Three-dimensional Study Of Upper Airway In Adult Skeletal Class â…¡ Patients With Different Vertical Patterns

Craniomaxillary complex provided hard support for the upper airway form,and theairway was supposed to play a role in dentofacial development.According to the closerelationship between the pharyngeal structures and dentofacial structures in ObstructiveSleep Apnea and Hypopnea Syndrome (OSAHS) patients,a mutual association wasexpected to exist between the pharyngeal structures and the dentofacial pattern in thecommon population.A smaller pharyngeal area had been observed more often in patientswith skeletal Class Ⅱmalocclusion.The mutual association between sagittal skeletalpattern and pharyngeal structures had been studied throughly,but the effects of verticalskeletal pattern in patients with skeletal Class Ⅱmalocclusion on the upper airwaydimension was still unknown.Evaluation of the airway is an essential diagnostic step for patients with breathingdisorders.In these patients,airway assessment has been mostly performed ontwo-dimensional lateral cephalograms by identifying special landmarks and measuring limitations with the inherent errors of a2D representation of a3-dimensional (3D)structure being distortion, differences in magnifications, superimposition of the bilateralcraniofacial structures, and in addition, a low reproducibility as a result of difficulties inlandmark identification. Another important drawback of lateral and frontal cephalogramsis the lack of information about cross-sectional area and volume. As biomedical imagingtechnology progresses,Clinical studies of the upper airway are usually undertaken usingcone-beam computed tomography (CBCT).3D imaging techniques can provide valuableinformation to clinicians and researchers due to the trend away from traditional2Dcephalometric analysis to more advanced3D visualization techniques.Objective：Patients with OSAHS (obstructive sleep apnea and hypopnea syndrome) demonstratedecreased upper airway dimension and craniofacial skeletal abnormalities.The study wasperformed to analyze whether pharyngeal airway differed among nonsnoring adults ofdifferent vertical skeletal facial morpnoiogies,and to study the potential association ofvertical skeletal facial patterns with different parts of upper airway.Methods:Cone-beam computed tomography（CBCT）records of64adult skeletal Class Ⅱpatients (34male and30female) were used to evaluate the nasopharyngeal andpalatopharyngeal and glossopharyngeal airways dimensions and volumes.The sample witha Class Ⅱ sagittal facial pattern (ANB angle>5°) was divided into three subgroupsaccording to the GoGn-SN angle(low angle,normal angle,or high angle). All subgroupswere matched for age and sex.Upper airway differrences were measured and comparedamong different vertical facial type groups.Results:In the linear measurements of upper airways,a significant tendency for reduced upperairway dimension in the superior part (nasopharynx and palatopharynx) was found in thelow angle, normal angle, and high angle subgroups,in that order,with statisticallysignificant difference(p<0.05). No statistically significant difference for upper airwaywidth was observed among different vertical skeletal facial morphologies.There was no difference in upper airway total volume among different vertical skeletal patterns.The glossopharynx height(Hg)and volume(Vg) of the high angle groupwas statistically significant difference with that of the low and the normal angle group（P<0.05）,No difference between glossopharynx height (Hg) and volume(Vg) of the lowangle group and that of normal angle group was found.Vp,Vg, Hp, Hg,CSAp and CSAg were significantly positively correlated with ODI.Vp, Hp and CSAp were significantly negatively correlated with FMA angle as well asGoGn-SN angle.Conclusions:The vertical skeletal patterns may be contributory factors for the variation of thenasopharynx and palatopharynx,and the vertical skeletal patterns showed different effectson different parts of the upper airway.