Predicting the pharyngeal airway space after mandibular setback surgery

Area of Science:

• Orthodontics and Maxillofacial Surgery
• Biomedical Engineering
• Airway Physiology

Background:

• Skeletal Class III malocclusion often requires surgical correction.
• Mandibular setback surgery can impact the pharyngeal airway space (PAS).
• Predicting PAS changes is crucial for patient outcomes and safety.

Purpose of the Study:

• To develop a predictive mathematical model for pharyngeal airway space (PAS) changes following mandibular setback surgery.
• To quantify the relationship between skeletal changes and PAS alterations.

Main Methods:

• A cohort of 23 female adults with skeletal Class III deformity was studied.
• Mandibular setback surgery (Bilateral Sagittal Split Ramus Osteotomy - BSSO) and orthodontic treatment were performed.
• Pharyngeal airway space (PAS) measurements were taken before (T1) and 1-1.5 years after (T2) surgery.

Main Results:

• A regression equation was derived to predict PAS changes: PAS narrowing = 0.386 - 0.541 ANB (T1-T2) + 0.253 Co-Gn (T1-T2) - 0.098 SN-GoGn (T1-T2).
• The model accurately predicted 66.2% of PAS changes using variations in ANB angle, condylion-gnathion length, and sella-nasion-gonion-gnathion angle.
• Key cephalometric variables influencing PAS were identified.

Conclusions:

• The developed equation effectively predicts pharyngeal airway space alterations post-mandibular setback surgery.
• Patients with risk factors like obesity or macroglossia may face increased sleep apnea risk after surgery.
• The model can inform surgical planning and patient counseling regarding potential airway complications.