Relationship between malocclusion and state of the upper respiratory tract, position of the tongue and hyoid bone

Objectives Malocclusions are among the main dental diseases and take second place after dental caries. The etiological factors for the occurrence of malocclusion include genetic factors, environmental and socioeconomic factors, as well as various bad childhood habits. Diseases of the upper respiratory tract deserve special attention, which can lead to oral breathing and the formation of malocclusion. Studying the relationship between craniofacial skeletal characteristics, position of the tongue and hyoid bone, and state of the upper respiratory tract, as a complex of interrelated factors, can become a new tool for diagnosing the etiopathogenesis of malocclusions and contribute to increasing the effectiveness of orthodontic treatment. Material and Methods We performed 67 cone beam computed tomography of the facial skeleton of orthodontic patients. The average age was 16.7 ± 5.1 years. Research of the respiratory tract was carried out at the level of standard anatomical landmarks on mid-sagittal sections at the level of the palatal plane, the base of the soft palate, and the base of the epiglottis. The position of the hyoid bone was studied by linear and angular parameters. The size and position of the tongue were measured on a mid-sagittal section along the residual space of Donders. Results It has been reliably established that in the II class, upper and middle airways are significantly narrower than in the III class. The Donders space is the largest in the I class - 5.91 ± 4.5 mm, the smallest in the III class - 2.99 ± 3.3 ( P = 0.049), that is, the tongue occupies a higher position in the III class than in the I class. The vertical position of the hyoid bone, both in terms of distance from the palatal plane and relative to the C 3 Me plane, is significantly lower in the I class than in the III class. Therefore, retroposition of the mandible may narrow the pharyngeal airway by moving the hyoid bone backward, while forward displacement of the mandible may increase this space. Conclusion Thus, assessment of the upper respiratory tract in patients with malocclusion is important for determining the orthodontic treatment plan.