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

Abstract

Objective: 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).

Materials and methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Cleft lip; Cleft palate; Computed tomography; Maxillary expansion; Upper airway.

Figures

Figure 1.

Rapid maxillary expanders. (A) Hyrax. (B) Fan-type. (C) iMini-M. (D) iMini-B.

Figure 2.

(A) Anterior maxillary width (AMW) with a coronal slice that best shows the crown of each anterior tooth. The dashed line intersects the cemento-enamel junction (CEJ) on the palatal surface of the teeth. (B) AMW with axial cut determined by the line on the coronal slice where the distance of the median point of the palatal surface of the dental crown and a median line was measured. The values for right and left sides were summed and represent the AMW. (C) Posterior maxillary width (PMW) with a coronal slice that best shows the crown of each posterior tooth. The dashed line intersects the CEJ on the palatal surface of the teeth. (D) PMW with axial cut determined by the dashed line on the coronal slice where the distance of the median point of the palatal surface of the dental crown and a median line was measured. The values for right and left sides were summed and represent the PMW.

Figure 3.

Limits of the oropharynx. (A) The upper limit is the palatal plane extended to the pharyngeal posterior wall, and the lower limit is the plane parallel to the palatal plane intersecting the lower and most anterior point in the second cervical vertebra. The horizontal white line represents the most constricted axial area in the oropharyngeal (minimum axial area). (B) Three-dimensional view of the oropharynx. The gray plane represents its minimum axial area.

Figure 4.

Limits of the nasal passage. (A) Determination of the last axial slice before the fusion of the nasal septum with the pharyngeal posterior wall. (B) The reflection of that slice in the sagittal plane defines the upper limit, and the palatal plane determines the lower limit.