We read the article ‘Changes in oropharyngeal airway and respiratory function during sleep after orthognathic surgery in patients with mandibular prognathism’ by H asebe et al. with keen interest. Our surgical team has been carefully studying this group of patients as we feel that the influence of class-III orthognathic surgery on the upper airway is an important topic that needs longitudinal analysis.
They reported their experience with 22 patients with bilateral sagittal split osteotomy together with Le Fort I osteotomy in 11 patients and without Le Fort I. osteotomy in the rest of the patients. They concluded the results of their study as ‘large amount of mandibular setbacks can inhibit biological adaptation and cause sleep disordered breathing, and it might be better to consider maxillary advancement or another technique that does not reduce the airway for patients with skeletal class III malocclusion, who have large anteroposterior discrepancy and/or maxillary hypoplasia.’ Although authors recommend considering concomitant maxillary advancement, they did not discuss relevant published results on this method of treating class III patients.
Iin our recent studies, we have shown that class III patients that undergo bimaxillary orthognathic surgery often have a post-operative increased upper airway resistance, a deterioration of the respiratory disturbance index, a higher oxygen desaturation index, a higher index of flow limitations as well as number of obstructive hypopnoeas and apnoeas . Thus, we feel that when treating a patient with class III malocclusion with a mandibular BSSO setback, the addition of a maxillary advancement may not improve and can worsen the upper airway resistance. Therefore, there should be no assumption that adding a maxillary advancement to the treatment plan will guarantee any significant improvement on the upper airway. Thus we recommend that a patient with class III malocclusion must have a thorough pre-operative airway assessment as part of the treatment plan.