Surgical mandibular setback and changes in uvuloglossopharyngeal morphology and head posture: a short- and long-term cephalometric study in males

A detailed cephalometric analysis was conducted on a sample of 31 adult males who underwent correction of mandibular prognathism by mandibular setback osteotomy (BSRO) with rigid fixation to evaluate the changes in uvuloglossopharyngeal morphology, hyoid bone position and head posture. Lateral cephalograms were obtained 1-3 days prior to the operation and at standardized 6 months and 3 years post-operative follow-up. Statistical evaluation was performed by paired Student's t-test and Pearson product moment correlation analysis. Inferior position of the hyoid bone (AH⊥FH, AH⊥ML, AH⊥S) and valeculla (V⊥FH) was recorded at the 6-month follow-up, a transient finding as at 3 years almost complete recovery to their pre-surgical position was noted. No posterior displacement of the above structures (AH-C3 Hor, V-C3) was recorded. Soft palate length (pm-U) was increased and maintained at the long-term follow-up while its posture (NL/pm-U) became less upright. The tongue showed increased length (V-T) and sagittal area (TA) and a more upright posture (VT/FH) at the late follow-up. Increased contact length between tongue and the soft palate (CL) and less residual oropharyngeal area [area not occupied by soft tissues, (TA+SPA)/OPA] was found at the long-term follow-up. Craniocervical agulation (NSL/OPT, NSL/CVT) was increased indicating cervical hyperflexion at the 3-year follow-up. Reduction of the sagittal dimension of the oropharyngeal airway space (U-MPW) appeared at the first follow-up and was sustained at the longest follow-up which, in conjunction with the decrease in residual oropharyngeal area, could raise questions regarding airway patency after mandibular setback osteotomy.