Respiration is a vital functional process that has effects on normal craniofacial development. Since the upper airway formations and dentofacial structures are adjacent to each other, the interaction between them is possible. The aim of this study is to evaluate the effects of removable functional appliances used in the treatment of patients with mandibular and maxillary growth retardation-stenosis in Class I, Class II, and Class III malocclusion on the upper airway.

Thirty two patients were studied in the study. The patients were divided into 4 groups according to treatment modalities. Maxillary expansion device group (Group A), Twinblock-Monoblock group (Group B), Face mask group (Group C), and Chincup group (Group D). The upper airway size in the lateral cephalometric images of the patients before orthodontic treatment with removable functional appliances (T0) and the upper airway size in the lateral cephalometric images taken after the end of the orthodontic treatment with the removable functional appliances (T1) were retrospectively compared.

Most upper airway size increased after orthodontic treatment (T1) in the individuals who received orthodontic treatment with A, B, C, and D type removable functional appliances compared to pre-treatment (T0). When the changes in upper airway size pre-treatment (T0) and post-treatment (T1) were compared, the change in upper airway size according to treatment groups was found to be statistically different (p <0.05).

Since a large part of the upper airway is located in the craniofacial complex, orthodontists also examine the airway for diagnosis and planning and can regulate the airway in case of occlusion that has occurred or may occur. This puts orthodontists in an important place to intervene when complications occur or may develop in the upper airway. By determining the effects of removable functional appliances on the airways, airway problems that may be experienced at an early age can be prevented.