Changes in pharyngeal airway space and hyoid bone position after Bionator treatment of skeletal Class II malocclusions

Abstract

Abstract Objectives The objective of this study was to investigate the treatment effectiveness of long-term Bionator use on the craniofacial pattern, nasopharynx, oropharynx, hypopharynx, hyoid bone, and cervical vertebrae in patients presenting with a skeletal Class II malocclusion involving mandibular retrognathia. Methods A treatment group of 27 patients with a skeletal Class II malocclusion treated using a Bionator was compared with a control group of 27 patients presenting with a skeletal Class I malocclusion managed without Bionator treatment. The Bionator was worn in the subject group until the complete eruption of the second molars. Lateral cephalograms of the group before (T0) and after Bionator treatment (T1) were compared. A two-way analysis of variance and a paired t-test were applied for statistical analyses. Results A significant increase in the SNB angle and a decrease in the ANB angle were apparent in the Bionator treatment group. The dimensions of the oropharyngeal and hypopharyngeal airways and the hypopharyngeal area increased significantly. Conclusion Long-term treatment using a Bionator resulted in the advancement of a retrognathic mandible. In addition, the dimensions of the oropharyngeal and hypopharyngeal airways and the hypopharyngeal area increased significantly, reaching the same level as that of skeletal Class I subjects.