
Background: Different exams can provide clinical information in mouth breathing children undergoing rapid maxillary expansion (RME) and to assess the effect of this procedure on nasal airway, however the correlation among these exams remains unclear. Objective: Evaluate through two methods of exams, the volumetric changes of the anterior nasal cavity post-RME. Methods: Nasal cavity changes in fifty mouth breathers, undergoing RME, were evaluated by acoustic rhinometry (AR); ten children were selected from the total sample and examined by acoustic rhinometry and computed tomography (CT). AR and CT were undertaken at pre-RME (T1) and 3 months post-RME (T2), and the correlation between AR and CT was estimated. Results: Significant increase in nasal volume demonstrated by both methods in basal conditions revealed that RME has a great effect on the nasal valve area, which have a significant value for rhinology. Conclusion: Correlation was observed between AR and CT in anterior nasal cavity.