Pharyngeal airway changes following symohyseal distraction osteogenesis

Introduction: The aim of this study was to analyze the effects of mandibular symphyseal distraction osteogenesis (MSDO) on the pharyngeal airway dimensions in a group of adult patients.
Subjects and Methods: The sample consisted of digital lateral cephalograms of 10 patients (7 females and 3 males)
with a mean age of 21.0 ± 2.5 years. Radiographs were taken before start of distraction (T1) and following distraction
(T2) (12.5 days ± 2.3 days after surgery). Symphyseal distraction was done using a bone-borne distractor. The mean value of mandibular symphyseal distraction was 8.4 ± 1.7 mm. Digital lateral cephalometric tracing was done to evaluate airway changes following symphyseal distraction.
Results: Digital lateral cephalometric analysis revealed no statistically significant changes in nasopharyngeal airway
(0.3 ± 0.1 mm) (P > 0.05). There were statistically significant changes in oropharyngeal and hypopharyngeal airway widths (1.2 ± 0.3 mm) and (0.7 ± 0.4 mm) respectively (P < 0.01). Hyoid bone position showed insignificant changes for the value Walker P-H (- 1.1 ± 0.2 mm) and H-RGN (- 0.9 ± 0.4 mm) (P > 0.05) while statistically significant decrease were evident for the vertical measurement H-C3RGN (- 1.2 ± 0.2 mm) (P < 0.01).
Conclusion: The results propose that MSDO significantly affects the lower pharyngeal airway dimensions but has no effect on the upper pharyngeal airway measurements. No significant effects on hyoid bone position were observed except mild decrease of its vertical measurement to reference planes. The normal reflex mechanisms that conserve the patency of the airway may have negated any potential changes in the hyoid bone position.