Three-dimensional evaluation of upper airway following tooth and TOOTH-bone borne rapid maxillary expansion

The purposes of this study were to evaluate and compare the effects of tooth borne (Hyrax) and tooth-bone borne (Hybrid Hyrax) expansion appliances on upper airway using cone-beam computed tomography (CBCT). The records of thirty-three patients who had undergone rapid maxillary expansion with Hyrax or Hybrid Hyrax appliance weere evaluated in this study. The Hyrax group was composed of 17 patients (10 girls,7 boys) with a mean age of 14 ± 2.2 years, and the Hybrid Hyrax group was composed of 16 patients (8 girls, 8 boys) with a mean age of 13.7 ± 2.3 years. Upper airway and maxillary skeletal measurement were carried out on CBCT records taken before and 3 months after expansion. Data were statistically analyzed. Maxillary transversal skeletal measurements increased after expansion in Hyrax and Hybrid Hyrax group (p<0.001), however there were no statistically significant differences between groups (p>0.05). Nasal widths, the volume of the nasal cavity and nasopharynx were increased in both groups, whereas the increases in volumes and nasal widths at the level of first premolars were greater in Hybrid Hyrax group (p<0.05). Similarly, maxillary sinus volumes increased more in Hybrid Hyrax group compared to the Hyrax group (p<0.05). No significant difference was revealed between groups in terms of oropharyngeal volumetric changes (p>0.05). Upper airway dimensions increased significantly following tooth and tooth-bone-borne rapid maxillary expansion. However, Hybrid Hyrax appliance was more effective in increasing the anterior width and volume of the nasal cavity. Key words: Rapid maxillary expansion, Hyrax, Hybrid hyrax, Upper airway, Cone beam computer tomography (CBCT)