Lead Author Affiliation

Doctor of Dental Surgery

Lead Author Program & Year

DDS Year 2

Presentation Category

Research

Introduction/Context/Diagnosis

● Studies have shown that airway dimension can be correlated to skeletal/dental malocclusion, including anterior open bites.1 ● Counter-clockwise rotation of mandible or extrusion of incisors can be used to correct anterior open bites; however, their subsequent effect on airway dimension has not been well studied. ● Studies have shown that both the inferior oropharyngeal airway volume and cross-sectional area increased as the mandibular position is advanced forward (decreased mandibular plane angle).2 ● Previous 3D MRI studies have shown that total airway volume, retropalatal and retroglossal airway volume increased following open bite closure.3

Methods/Treatment Plan

● Retrospective study of open bite adult patients treated at UOP from 2006 (n=196) ● All subjects had T1 (before orthodontic treatment) and T2 (end of orthodontic treatment) CBCT ● Exclusions: orthognathic surgery and craniofacial patients ● Fifty-three cases were collected. ● The sample was divided into growing (Female younger than 15 yrs, Male younger than 18 yrs) and non-growing (Female older than 15 yrs, Male older than 18 yrs) groups for further analysis. ● Used 3D tracings and airway measurements (using Invivo 6) to evaluate changes in airway dimensions in various skeletal patterns - tracings were done by 2 judges ● 19 skeletal and 12 dental landmarks were evaluated

● Areas measured: ○ Upper oropharynx - From palatal plane (ANS-PNS) to base of soft palate parallel to FH ○ Lower oropharynx - From base of soft palate to epiglottic vallecula parallel to FH

● Airway measurements include: ○ Minimum cross-sectional area (MCA, mm2) ○ Volume (cc)

Results/Outcome

Impact of skeletal and dental changes during open bite treatment on airway: (n=52, 1 outlier excluded from analysis)

● Correlations between airway dimension and mandibular size, ANB, L1 position changes were statistically significant

● The patients presented with hyperdivergent Class II skeletal pattern before treatment (T1).

● Mandibular length change had positive correlations with upper airway volume (U.VOL), lower airway volume (L.VOL), and lower airway minimal crosssectional area (L.MCA). ● Mandibular ramus length change showed positive correlations with L.VOL and L.MCA. ● ANB angle showed a negative correlation with upper airway size. ● B point and pogonion (Pog) position change in the anterior-posterior (AP) dimension showed positive correlation with airway size. ● Upper and lower incisor positions in the AP dimension showed positive correlations with airway size.

● When one outlier was excluded, mandibular plane angle had no significant correlation with airway size.

● Dental or skeletal changes during open bite treatment did not present any statistically significant correlation with airway change in adults.

Significance/Conclusions

● Change in airway dimension showed statistically significant, moderate, positive correlations with amount of mandibular growth and anterior movement of B point and Pog in the growing group. ● Airway size change after open bite treatment did not show any significant correlation with skeletal/dental changes in the adult group.

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Airway dimension change after open bite treatment – 3D CBCT study

● Studies have shown that airway dimension can be correlated to skeletal/dental malocclusion, including anterior open bites.1 ● Counter-clockwise rotation of mandible or extrusion of incisors can be used to correct anterior open bites; however, their subsequent effect on airway dimension has not been well studied. ● Studies have shown that both the inferior oropharyngeal airway volume and cross-sectional area increased as the mandibular position is advanced forward (decreased mandibular plane angle).2 ● Previous 3D MRI studies have shown that total airway volume, retropalatal and retroglossal airway volume increased following open bite closure.3