Stability Of Oropharyngeal Airway Changes Following Orthognathic Surgery

Dr. Wolford discusses how maxillomandibular jaw advancement with counter-clockwise rotation produces immediate increases in middle and lower oropharyngeal airway dimensions which were constrained by changes in head posture, but remain stable over the post-surgical period.

The Post-Surgical Stability Of Oropharyngeal Airway Changes Following Counter Clockwise Maxillomandibular Advancement Surgery

By Joao Goncalves DDS, Danielle Goncalves DDS, Peter Buschang PhD, Larry M. Wolford DMD

Purpose:
This study evaluated oro-pharyngeal airway changes and stability following surgical counter-clockwise rotation and advancement of the maxillo- mandibular complex.

Methods and Patients:
56 adults (48 females, 8 males), between 15 and 51 years of age, were treated with LeFort I osteotomies and bilateral mandibular ramus sagittal split osteotomies to advance the maxillo-mandibular complex with a counter-clockwise rotation. The average post-surgical follow-up was 34 months.  Each subject’s lateral cephalograms were traced, digitized twice and averaged to estimate surgical changes (T2-T1) and post-surgical changes (T3-T2).

Results:
During surgery, the occlusal plane angle decreased significantly (8.6±5.80) and the maxillo-mandibular complex advanced and rotated counter-clockwise. The maxilla moved forward (2.4±2.7mmm) at ANS and the mandible was advanced 13.1±5.1 mm at menton, 10±4.4 mm at point B, 6.9±3.7 mm at lower incisor edge.  Post-surgical hard tissue changes were not statistically significant.

While the upper oro-pharyngeal airway decreased significantly (4.1 mm) at upper retropalatal airway space (URP) immediately after surgery, the narrowest retropalatal (RPnar), lowest retropalatal airway (U-MPW) and the narrowest retroglossal airway (PASnar) measurements increased 2.9±2.7, 3.7±3.2 and 4.4±4.4 mm respectively.  Over the average 34 months post-surgical period, URP increased 3.9±3.7 mm while RPnar, U- MPW and PASnar remained stable. Head posture showed flexure immediately after surgery (4.8±5.90) and extension post-surgically (1.6±5.6 deg).

Conclusions:
Maxillomandibular advancement with counter-clockwise rotation produces immediate increases in middle and lower oropharyngeal airway dimensions which were constrained by changes in head posture, but remain stable over the post-surgical period. The upper oropharyngeal airway space increased only on the longest follow-up.