Pharyngeal airway changes after functional orthodontic treatment: A retrospective case-control study on a pediatric population

BACKGROUND: Initiating orthodontic treatment before the pubertal peak results in more pronounced long-term craniofacial changes in the maxilla and adjacent structures. Dental malocclusion correction through maxillary expansion has been shown to significantly increase the patency and decrease the airflow resistance in several airway compartments, ranging from the nares to the epiglottis plane. OBJECTIVES: We aimed to assess the impact of treatment with a removable functional orthodontic appliance on the dimensions of selected sections of the upper respiratory tract in pediatric patients, with the goal of identifying the nasopharyngeal and oropharyngeal regions most susceptible to lateral maxillary and mandibular expansion. MATERIAL AND METHODS: We retrospectively reviewed the medical records and lateral cephalometric radiographs (LCRs) of all consecutive pediatric patients with deciduous or mixed dentition treated with a functional appliance between 2014 and 2019 at a private orthodontic practice in Racibórz, Poland. To assess the impact of the study group and gender on the dependent variables, a Multivariate Analysis of Covariance (MANCOVA) was performed. The variable T1 (age at treatment initiation) was included as a covariate in the model to control for its potential effect on the outcomes. RESULTS: The treatment group comprised 55 patients, while 24 subjects served as the control group. In contrast to the nasopharyngeal variables, the average annual increase in the oropharyngeal linear measurements was significantly greater in the treatment group. For the gender factor, after applying the Benjamini-Hochberg correction, no statistically significant differences were observed in any of the assessed variables. In contrast, after correction, the covariate T1 was statistically significant for the following variables: CVM1 and CVM2 (skeletal age before treatment initiation and after treatment completion, respectively), and T2 (chronological age after treatment completion). CONCLUSIONS: Although treatment with a removable functional appliance does not significantly impact the nasopharyngeal airspace, it significantly increases oropharyngeal dimensions, which may help reduce the future risk associated with abnormal breathing patterns in treated patients.