CBCT Analysis Of Upper Airway In Adult Patients With Skeletal Malocclusion

Objectives:Application of CBCT and Invivo5to compare upper airway of patients with different skeletal malocclusion on airway volume, shape, direction and hyoid position, analysis the influence of the maxillary or mandibular position. Discuss causal relationships and impact mechanism of airway and craniofacial morphology, in order to fault diagnosis of and provide guidance for reasonable and effective treatment.Methods:Screening CBCT data from November2011to February2014, tianjin medical university stomatological hospital radiology department, randomly selecte300cases,divided into five groups, each group including60cases,30male and30female, average age is24.5±3.6. Using Invivo5rebuild3d image data, establish a3d coordinate system, measuring NPV, OPV, Smin, observation the most narrow area and morphology, measure the sagittal and transverse distance;Take sagittal position to measurement∠OP, craniocervical angle, H-OP, H-VPS, H-PS;Take on the3d image to measure effectively length of maxillary and mandibular. The oneway ANOVA analysis of SPSS19.0was used to compare variance between each group, then take LSD-t comparison and Pearson correlation analysis.Results:1. Nasopharynx airway volume have no statistical difference (P>0.05). Mandibular retraction of Skeletal Class II has the minimum value.2. OPV have statistical difference (P<0.05). Mandibular retraction of class II compaired with class I, maxillary retrusion of class Ⅲ, mandibular protrusion of class III were all have statistically significance (P<0.05), with the minimum OPV of8.89±3.51cm3; mandibular protrusion of class Ⅲ compared with others have statistically difference (P<0.05),with the maximum of23.46±5.56cm3.3. Smin, sagittal and transverse distance, have statistically difference (P<0.05). The ratio of sagittal and transverse distance and H-OP have no statistical difference (P>0.05). Mandibular retraction of skeletal class II has the minimum Smin, sagittal and transverse distance value with an average of103.40±57.83mm2、6.22±2.03mm、21.99±5.02mm; mandibular protrusion of skeletal class Ⅲhas the maximum value of 381.57±115.95mm2、11.75±2.50mm、34.88±4.38mm.4.∠OP have statistically difference (P<0.05). Mandibular retraction of class Ⅱ is larger than the others, present a more lean back airway; mandibular protrusion of class Ⅲhas the minimum angle, present a more upright airway. Craniocervical angle have no statistically difference. Class II have larger craniocervical angle, present a more stretch head position, craniocervical angle and∠OP are positive related.5. H-VPS have statistically difference (P<0.05). H-VPS in mandibular retraction of class II significantly reduced with retraction position, H-VPS in mandibular protrusion of class Ⅲis mostly in the front. H-PS have no statistical difference.6. Significant differences airway measuring project within five groups between male and femalehave no statistical difference (P>0.05), male value is larger.7. OPV and Smin were positively correlated with Co-Po, SNB, NP-FH, H-VPS, sagittal and transverse distance, while negatively with ANB, NA-PA, the most relevant variables with OPV is Smin (r=0.912). The correlation in mandibular position is more closely than maxilla, especially the size and length of mandibular.Conclusion:1.3D characteristics of opharynx airway are differences, mandibular sagittal position and size have more significant impact on OPV, shape, direction, hyoid position.2. Oropharynx minimum cross-sectional zone mainly in velopharynx the area after soft palate, overall present ellipse since transverse distance is greater than the sagittal.3. In the sagittal view,∠OP are different, craniocervical angle and oblique angle of oropharynx are related.4. H-VPS are different in adult patients with different skeletal malocclusion, hyoid position change have a link to mandibular, airway volume and craniocervical angle.5. Craniofacial skeleton with abnormal morphology and position will influence on the airway, detailed and valuable diagnostic program should be added to the orthodontics.6. CBCT and Invivo5measure OPV airway volume is more accurate and reliable than NPV, especially for Smin has a certain advantage.