Effects of rapid maxillary expansion on upper airway volume: A three-dimensional cone-beam computed tomography study

Abstract

Objective: To compare changes in pharyngeal airway volume and minimal cross-sectional area (MCA) between patients undergoing rapid maxillary expansion (RME) and a matched control group and to identify markers for predicting airway changes using cone-beam computed tomography (CBCT).

Materials and methods: Pre- and posttreatment CBCT scans were selected of children who had RME (14 girls and 12 boys; mean age, 12.4 years) along with scans of a control group (matched for chronological age, skeletal age, gender, mandibular inclination) who underwent orthodontic treatment for minor malocclusions without RME. Changes in airway volume and MCA were evaluated using a standardized, previously validated method and analyzed by a mixed-effects linear regression model.

Results: Upper airway volume and MCA increased significantly over time for both the RME and matched control groups (P < .01 and P = .05, respectively). Although the RME group showed a greater increase when compared with the matched controls, this difference was not statistically significant. A reduced skeletal age before treatment was a significant marker for a positive effect on the upper airway volume and MCA changes (P < .01).

Conclusions: Tooth-borne RME is not associated with a significant change in upper airway volume or MCA in children when compared with controls. The younger the skeletal age before treatment, the more positive the effect on the upper airway changes. The results may prove valuable, especially in RME of young children.

Keywords: CBCT; Children; Maxillary expansion; Upper airway volume.

Figure 1.

Illustration of margins for delineation of upper airway. Superior: line passing from the palatal plane (ANS – PNS) extending to the posterior wall of the pharynx. Inferior: line passing from the anterosuperior edge of the fourth cervical vertebra (C4) to menton (Me). Anterior: line passing from soft palate to menton (Me). Posterior: posterior wall of pharynx. Lateral: respective pharyngeal walls.

Figure 2.

Illustrations of transverse skeletal and dental measurements. (A) posteroanterior cephalometric reference points (Mx: intersection of the lateral contour of the maxillary alveolar process and the lower contour of the maxillozygomatic process of the maxilla; Go: the most lateral point on the angle of the mandible) and lines (dotted) measuring the maxillary width (Mx-Mx) and mandibular width (Go-Go). (B) Intermolar width measurement from the most palatal aspects of the upper first molars at the level of the cementoenamel junction.