Objective: The aim of this study was to evaluate the nasal cavity transversal dimensions by CT scan and the respiratory function by rhinomanometry in patients with oral breathing and posterior cross-bite before and after rapid palatal expansion treatment.
Methods: Thirteen oral breather patients with posterior cross-bite were studied. Treatment consisted in rapid palatal expansion with a fixed appliance including a bite-block and a Hyrax expansion screw. Before and after treatment, CT scans and rhinomanometry was performed to each patient. At the CT scan, three coronal slices were taken and transversal measurements were obtained from each one. Active anterior rhinomanometry was used to quantitatively assess the pressure of the air that flows through the nasal cavity. During the exam a vasoconstrictor (oximetazoline) was applied and measurements were obtained before and after the medication, at inhale and exhale, in both right and left side separately. Data was analyzed with the non-parametric Wilcoxon statistical test.
Results: The CT scan showed that all transversal dimensions were significantly increased (P<0.05) after treatment, considering the right and left side separately. Rhinomanometry also showed statistical significance (P<0.05) in all parameters studied when compared before and after treatment.
Conclusions: All patients improved oral breathing habit clinically and there is also statistical evidence that the nasal cavity increases its transversal dimensions, measured by CT scan and that patients increase their air flow through the nasal cavity, measured by rhinomanometry.