Changes of Pharyngeal Airway Size and Hyoid Bone Position Following Orthodontic Treatment of Class II Open Bite Patient
Author(s): Vahid Mollabashi, Majid Mahmoudzadeh, Faezeh Yousefi, Maryam Farhadian, Zahra Lotf Haghpanah, Ali Reza Noorani
Abstract
The aim of this study was to investigate the changes of pharyngeal airway dimension and hyoid bone position after orthodontic treatment of class II open bite patients with extraction of two premolars in the upper arch Lateral cephalograms of 34 patients with class II open bite malocclusion in pre & post treatment used to assess the changes in hyoid position, and upper airway dimensions. All patients were treated with 0.022 * 0.028 inch preadjusted appliances after extraction of two first premolars. Anchorage was reinforced with maximum anchorage mechanics using headgears or mini-implants, depending upon the patients’ compliance. Pretreatment and post treatment variables were compared using paired t-test. The mean SPAS (0.98 ± 2.73 mm, P < 0.05) had statistically significant decrease following orthodontic treatment. No significant change was found in any other parameter about airway and hyoid bone position. In dentoskeletal measurements mandibular plane angle did not show any significant change, whereas ANB degrees (1.29 +/- 0.93, P < 0.01) decreased significantly after treatment. This effect was associated with a significant decrease in SNA degrees (0.67 +/- 0.72, P < 0.01) and significant increase in SNB degrees (0.61 +/- 0.77, P< 0.01). Upper airway size and hyoid bone position have clinically insignificant changes after orthodontic treatment of class II open bite patient with extraction of two upper premolars.
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