Airway changes with surgical orthodontic treatment of class III malocclusion

Objective: To determine changes in the oropharyngeal airway in Class III patients treated by bimaxillary surgery, and to find possible correlation between oropharyngeal airway changes and the skeletal movements. Materials and Methods: Lateral cephalograms of 30 class III patients (16 females, 14 males, age: 18-25 years old) treated with maxillary advancement and mandibular set-back were evaluated presurgery (T1), post-surgery (T2) and 12 months post-surgery (T3). The anteroposterior oropharyngeal airway and skeletal changes of the maxilla and mandible were measured. ANOVA was performed to determine significant differences between the different time points. Pearson correlation coefficient was used to assess correlations between the changes in oropharyngeal airway and the amount of jaws movements. Results: Parameters indicating anteroposterior maxillary position showed significant increase from T1 to T2 and from T1 to T3. Parameters indicating antero-posterior mandibular position showed significant decrease from T1 to T2 and from T1 to T3. Anteroposterior oropharyngeal airway space showed significant increase from T1 to T2 and from T1 to T3. All measured variables in the study showed insignificant differences between T2 and T3 indicating insignificant relapse of the surgically induced changes. Pearson's correlation analysis showed a statistically significant moderate positive correlation between the oropharyngeal airway increase and the amount of the maxillary advancement, while no correlation was found with the amount of mandibular setback. Conclusions: Combined maxillary advancement and mandibular setback surgeries lead to an increase in the anteroposterior dimension of the oropharyngeal airway. Which is positively correlated to the amount of maxillary advancement only. Introduction Skeletal class III malocclusion is manifested as a discrepancy in the anteroposterior relationship of the maxilla and mandible. The severity of the deformity, the amount of the desired correction, and the expected facial improvement after surgery, affect the treatment of choice. Surgical correction of skeletal class III cases by a combination of bimaxillary surgery has a great effect on the facial esthetics and the patient’s self-esteem. However, it has another functional effect on the oropharynx. The complex anatomy of the oropharynx is pivotal to its function. The pharyngeal muscle tone essential to its patency is reduced during sleep, thus substantiating the role of proper pharyngeal anatomy to guard against airway collapse. Therefore objectives as improving occlusion and aesthetics, should be planned with attention to the pharyngeal function. Several studies reported a reduction of the pharyngeal airways after mandibular setback surgery. Long follow-up showed maintenance of this reduction. At the same time, Mao et al found that although there was some increase in both the airway space width and area during the follow-up period, they did not increase to their original values. On the other hand, some studies suggested that the changes in the oropharyngeal complex are temporary as the tissues re-adapt, leading to self-correction. Findings of studies addressing the relationship between double jaw surgery and pharyngeal airway are contradicting, maybe due to the complex anatomy and physiology of the pharynx, together with the different methods of measuring the airway, and differences in the amounts of surgical jaw movements. Some studies reported a Assistant professor, Department of Orthodontics, Faculty of Dentistry, Alexandria University, Egypt b Professor, Department of Orthodontics, Faculty of Dentistry, Alexandria University, Egypt Egyptian Orthodontic Journal 77 Volume 60 – December 2021 ISSN: 1110.435X significant decrease of the upper pharyngeal airway dimensions, while others have indicated that the decrease in the pharyngeal airway space after double jaw surgery was less than with mandibular setback alone, other studies reported increase in the pharyngeal airway space after bimaxillary surgery, while others found no effect on the airway. Hence, this study was designed to answer the question; how does maxillary advancement and mandibular set back affect the oropharyngeal airway space?