Acoustic rhinometric measurements in children undergoing rapid maxillary expansion.

Objective: To evaluate geometric changes of nasal cavities in children undergoing rapid maxillary expansion and to assess the effect of this procedure on nasal airway size by means of acoustic rhinometry.
Method: We recruited 14 mouth-breather children (mean age 8.2 years) presenting constricted maxillary arches and scheduled for rapid maxillary expansion in the orthodontics department of our hospital. Clinical history did not reveal any allergic diseases and ENT examination was completely normal with a well-aligned nasal septum. Nasal measurements were obtained using acoustic rhinometry, which was performed before the expansion treatment and after 1-year follow-up. A postero-anterior radiograph of the skull was also performed in all patients for cephalometric analysis before and 3 months after the treatment.
Results: We observed a satisfactory increment in the transverse dimension of the maxilla in all patients but one who manifested a relapse after 4 months from the treatment and required a second procedure. Similarly, acoustic rhinometric measurements and cephalometric tracings showed a statistically significant increase respectively in decongested total nasal volumes (p=0.047) and in binasal cavity width (p=0.001). However, only eight children switched their respiration from oral to nasal breathing mode.
Conclusions: Rapid maxillary expansion is an effective method for increasing the width of narrow maxillary vault and it is also associated with a significant increment in nasal volumes and in the transverse diameter of the maxilla. With regard to breathing posture, the role of this procedure still remains debatable. To date this is the first study aimed at analysing the effects of rapid maxillary expansion on nasal dimensions by means of acoustic rhinometry.