Three-dimensional evaluation of upper airway following rapid maxillary expansion: a CBCT study.

OBJECTIVES: To evaluate, by using cone beam computed tomography, the skeletal, dental, oropharyngeal (OP) airway volume, and nasal passage (NP) volume changes that occur after rapid maxillary expansion (RME). MATERIALS AND METHODS: Two groups were selected, each with 35 patients (15 males, 20 females), an RME group (mean age, 14.02 +/- 1.46 years) and a control group (mean age, 14.10 +/- 1.44 years). The RME group consisted of patients with maxillary constriction who were treated with Hyrax palatal expanders, and the control group comprised age- and sex-matched patients who underwent comprehensive orthodontic treatment without the use of a rapid maxillary expander. RESULTS: All of the transverse skeletal (medial orbital width, lateral nasal width, maxillary width, and mandibular width) and interdental (intermolar, interpremolar, and intercanine) parameters were significantly enlarged in the RME group. A statistically significant increase in airway variables was seen in both groups between pretreatment (T0) and final records (T1). The mean increase of NP airway volume for the RME group (1719.9 +/- 1510.7 mm(3)) was twofold compared with the control group (813.6 +/- 1006.7 mm(3)), and no intergroup significant difference was found for the OP volume. CONCLUSIONS: Rapid maxillary expansion creates a significant increase in nasal passage airway volume but no significant change in the oropharyngeal airway volume.