Short-term Volumetric and Minimal Area Changes in the Pharyngeal Airway After Use of a Fixed Functional Appliance: A Three-dimensional CBCT Investigation

Objective Functional appliances are used in orthodontics to bring about correction of mandibular retrognathism by forward positioning and eventually remodeling the condyle- glenoid fossa to retain this new position. Research has shown that these appliances have a significant effect on pharyngeal airway of patients. The aim of this study was to evaluate changes in volume and minimum constriction area in the pharyngeal airway using CBCT imaging after correction of mandibular retrognathism with an Advansync2 Class II corrector. Methods This single-center study consisted of 20 Class II patients (mean age 14.8 years) who required correction of mandibular retrognathism. The patients were treated with the Advansync2 Class II corrector for an average of 26 weeks. CBCT records were taken at T0 (beginning of treatment) and T1 (end of functional phase). The airway was segmented into lower nasopharynx, velopharynx and oropharynx and analyzed for changes in partial volume, total volume, and minimum area using a CBCT software [NewTom 3G TM (Newtom- Cefla S.C., Verona, Italy)]. Results The partial and total volumes were significantly larger at T1 than at T0 ( p = .003, .001). In addition, minimum area also improved in each part of the airway ( p = .005, .022, .001). Conclusion The Advansync2 fixed functional appliance can be used in Class II patients requiring improvement in their airway dimensions. However, additional long-term studies are recommended to confirm these findings.