Upper airway assessment using four different maxillary expanders in cleft patients: A cone-beam computed tomography study

To evaluate the anterior and posterior maxillary width, the nasal passage volume, the oropharyngeal minimum axial area, and volume changes in unilateral cleft lip and palate patients treated with one of the following four expanders: Hyrax, Fan-Type, inverted mini-hyrax supported on the first permanent molars (iMini-M), or inverted mini-hyrax supported on the first premolars (iMini-B). A total of 40 patients with transverse maxillary deficiency who were submitted for rapid maxillary expansion were divided in four groups according to type of expander used. Cone-beam computed tomography images were taken before and 3 months after expansion. One-way analysis of variance was used to analyze the differences among the groups, and paired t-tests were used to evaluate the changes in each group. All groups showed a significant increase in the anterior maxillary width, with no intergroup differences. The iMini-B was the only group that did not show a significant increase in the posterior maxillary width. The intergroup comparison demonstrated differences among all groups except between Hyrax and iMini-M, which showed the greatest posterior expansions. The intragroup analysis showed a significant increase in the nasal passage volume in hyrax and inverted mini-hyrax on the molar groups, but the intergroup comparison revealed a significant difference only between Fan-Type and inverted mini-hyrax on the molars. None of the expanders caused significant changes in the oropharyngeal measurements. Only the Hyrax and inverted mini-hyrax on the molar expanders effectively increased the nasal passage volume, and none of the expanders evaluated in this study modified the oropharyngeal airway.