Airway compartments volume and oxygen saturation changes after rapid maxillary expansion: a longitudinal correlation study.

OBJECTIVE: To evaluate changes in airway volumes and respiratory performance in patients undergoing rapid maxillary expansion and determine whether any correlations exist between the morphological and respiratory functional modifications induced by rapid maxillary expansion and pretreatment airway stenosis. MATERIALS AND METHODS: Fifteen patients (11 females and 4 males; mean age, 7.5 +/- 0.3 years) were enrolled in the study. Each patient underwent cone beam computed tomography and polysomnography examination before rapid maxillary expansion and after the removal of the maxillary expander 12 months later. The airway regions were segmented and the volumes were computed. RESULTS: The upper, middle, and lower airway volumes were significantly increased 2305 mm(3), 1144 mm(3), and 1915 mm(3), respectively. Similarly, oxygen saturation was increased (+5.3%) and the apnea/hypopnea index was improved (-4.2 events). All the observed modifications were statistically significant (P < .05). Baseline middle and lower airway volume showed a significant negative correlation with the oxygen saturation modification. CONCLUSIONS: The results of this study showed that when rapid maxillary expansion is performed in subjects having posterior crossbite, oxygen saturation is improved. The improvement is greater in subjects having more reduced middle and lower airway volumes.