Two methods of treatment for skeletal Class Ⅲ malocclusion on airway changes before and after clinical research

To investigate the changes in the sagittal diameter of the upper airway before and after the treatment of skeletal Class Ⅲ malocclusion in adults with microimplant anchorage and class Ⅲ intermaxillary elastics and to provide a reference for clinical treatment.

A total of 35 adult patients with skeletal Class Ⅲ malocclusion were selected to be treated with the straight-wire technique. Microimplant group, 15 cases (group A): patients with severe skeletal Class Ⅲ malocclusion (vertical high angle) were treated with the straight-wire technique combined with microimplant anchorage; class Ⅲ intermaxillary elastics group, 20 cases (group B): Patients with mild or moderate skeletal Class Ⅲ malocclusion (vertical low angle and average angle) were treated with the straight-wire technique combined with class Ⅲ intermaxillary elastics, and cephalometric radiographs obtained before and after treatment in the upper airway in the two groups were measured and analyzed.

Changes in cranial and maxillofacial measurements after correction: in group A, (sella-nasion-supramental angle) the SNB angle decreased significantly (P < 0.05), and (subspinale-nasion-supramental angle) the ANB angle increased significantly (P < 0.05). In group B, the SNB angle decreased significantly (P < 0.05), while (subspinale-nasion-subspinale angle) the SNA angle、ANB angle and anterior skull base plane-mandibular plane angle (Sn-MP) angle increased significantly (P < 0.05). Changes in sagittal diameter of the upper airway measurements after corrections: In group A, the width of the glossopharyngeal segment of the upper airway (TB-TP-PW) decreased significantly (P < 0.05). In group B, first segment width of the upper airway behind the hard palate (PNSR) increased significantly (P < 0.05). After correction, the decreased SNB and increased ANB in group A was higher than that in group B, and the difference was statistically significant (P<0.05). The decreased of TB-TPPW in upper airway of group A was greater than that of group B, and the difference was statistically significant (P<0.05).

In the treatment of skeletal class Ⅲ malocclusion with microimplant anchorage, the sagittal diameter of the glossopharyngeal segment of the upper airway has a negative impact.